pyruvate to cytochrome bd oxidase electron transfer

MetaCyc:PWY-7545

This E. coli respiratory route comprises two biological events: PoxB oxidatively decarboxylates pyruvate to acetate and carbon dioxide while reducing ubiquinone, and cytochrome bd-I oxidizes the resulting ubiquinol while reducing oxygen to water. The quinone pool links the events. The native pathway explicitly excludes the bd-II APP-UBIOX-CPLX alternative, although the general terminal-oxidase reaction can have other catalysts. Pyruvate dehydrogenase, pyruvate formate-lyase, acetate assimilation and ATP synthesis are adjacent processes, not extra events in this record. (MetaCyc:PWY-7545; EcoCyc:PWY-7545.) The complete native PoxB event RXN-11496 is LEFT-TO-RIGHT: pyruvate(in) + water(in) + a ubiquinone → acetate(in) + carbon dioxide(in) + a ubiquinol. All six side coefficients are one. The complete bd-I event RXN0-5266 is PHYSIOL-LEFT-TO-RIGHT: 2 ubiquinols + dioxygen(in) + 4 hydrons(in) → 2 ubiquinones + 2 waters(in) + 4 hydrons(out). Thus the native route has twelve side occurrences; quinone-class sides have no explicit compartment. CCO-IN and CCO-OUT are generic membrane-side spaces, interpreted as cytoplasmic and periplasmic sides only in this E. coli inner-membrane context. (MetaCyc:RXN-11496; MetaCyc:RXN0-5266; EcoCyc:CCO-IN; EcoCyc:CCO-OUT.) Four constituent half-reactions retain eighteen side occurrences, including literal electron symbols. Stored reductions are ubiquinone + 2 H+(in) + 2 e− → ubiquinol; acetate(in) + CO2(in) + 2 H+(in) + 2 e− → pyruvate(in) + water(in); ubiquinone + 2 H+(out) + 2 e− → ubiquinol; and O2(in) + 4 H+(in) + 4 e− → 2 waters(in). The acetate/CO2 half-reaction must be reversed for PoxB, and the outer-side quinone half-reaction reversed and doubled for bd-I. These are constituent representations, not four additional forward biological steps. No invented free-electron identifier is assigned. (MetaCyc:RXN0-5244; MetaCyc:RXN0-6375; MetaCyc:TRANS-RXN0-237; MetaCyc:RXN0-5265.) RHEA:27406 and RHEA:40528 provide oriented source projections of the same two events. The former does not encode the native PoxB side compartments; the latter explicitly encodes 4 H+(in) and 4 H+(out). Whole Rhea Polymer objects 9565 and 9566 represent ubiquinone and ubiquinol with variable repeat n; their RHEA-COMP identifiers are retained without replacing them by the underlying ChEBI classes or an exact Q8 species. Native RHEA:29170 is an obsolete RELATED-TO reference replaced by master 27405. Native RHEA:30251 remains approved but uses symbolic n proton transport, so it is not an exact synonym for the explicit four-proton equation. (RHEA:27406; RHEA:40528; RHEA:29170; RHEA:30251; MetaCyc:RXN-11496; MetaCyc:RXN0-5266.) The frozen PathBank SMP0002099/PW002087 drawing has four events and fifteen side occurrences, with incomplete or inconsistent displayed stoichiometry: event 6089 has two pyruvates and waters but single acetate and CO2 products; 6090 lacks reduction donors; 6091 lacks electrons and has one proton; and 6092 has one electron rather than four. Its Q0 compounds and neutral pyruvic/acetic acids are distinct from the native generic carriers and selected anions. The frozen PoxB protein assignment is retained despite a later web highlight calling the protein pyruvate-dehydrogenase E1. Its CydA/B/X assembly is an archival projection, not proof that every native bd-I preparation lacks CydH. (PathBank:SMP0002099.) Native ubiquinones and ubiquinols are lipid-soluble benzoquinone redox classes with variable isoprenoid-chain length. Q8 or ubiquinone(40) describes eight isoprenoid units, not the entire class. The source lists different predominant lengths across organisms; these background distributions do not establish route activity in those taxa. Oxidized and reduced class names remain distinct despite informal interchangeable usage. E. coli K12 UniProt references, MG1655 native annotations, historical W/B preparations and engineered strains below are separate experimental scopes. (MetaCyc:Ubiquinones; MetaCyc:Ubiquinols; UniProtKB:P07003; EcoCyc:ENZRXN-17895.) The 1984 primary abstract reports reconstitution with two purified enzymes, pyruvate oxidase and cytochrome d oxidase, plus Q8 in phospholipid vesicles. Maximal pyruvate-dependent oxygen consumption was about 30% of membrane preparations and generated at least 180 mV inside-negative potential. Menaquinone-8 did not effectively substitute; Q1 supported a separate oxidase-only control. The abstract names valinomycin and an uncoupler spelled carbonyl cyanide p-(tri-chloromethoxy)phenylhydrazone. That spelling is retained without identifying it as FCCP. Full experimental details were not obtained, and this experiment does not establish exclusive whole-cell bd-I flux or an exact modern four-chain composition of the historical preparation. (PMID:6367818.) Cytochrome bd-I conserves energy through oriented quinol oxidation and oxygen-reduction chemistry without acting as a proton pump. Ubiquinol oxidation releases protons on the outer side while oxygen reduction uses inner-side protons. Spheroplast comparisons in the 1991 primary abstract support charge separation by cytochrome d; the separately reported bo3 proteoliposome H+/e− ratios of 0.3–0.7 concern bo3, not a measured bd-I pumping ratio. Native literature context assigns bd-I an H+/e− ratio of one and leaves the PoxB ratio unknown; cancellation of intermediates must not conceal these separate physical processes. (PMID:1850294; EcoCyc:CYT-D-UBIOX-CPLX; MetaCyc:PWY-7545.) The native PoxB complex is a homotetramer of the P07003 reference protein. The native modern bd-I assembly contains one each of CydA, CydB, CydX and CydH. A5A618 retains its issuing UniProt name Uncharacterized protein YnhF; CydH is the native structural assignment. Component membership does not show that isolated chains independently catalyze oxygen reduction. Historical two-band purifications, the frozen three-chain PathBank representation, recombinant tagged ABX preparations and the four-chain modern structure are kept as different observations. (EcoCyc:PYRUVOXID-CPLX; EcoCyc:CYT-D-UBIOX-CPLX; UniProtKB:A5A618; PMID:6307994; PMID:6321507; PMID:31604309.) PoxB is a peripheral membrane enzyme with FAD and thiamine diphosphate cofactors, with one of each per subunit in reviewed/native annotations and magnesium as the reference metal. The 1982 abstract tested Mg, Ca, Zn, Mn, Ba, Ni, Co, Cu and Cr(III) in four buffers; these are assay alternatives, not nine simultaneous physiological cofactors or nine divalent metals. It identifies metal–TPP as the functional cofactor, observes one Mn per subunit only with TPP, and describes a Mn–pyruvate abortive complex with a 70 mM dissociation constant. The selected charged cofactor forms do not themselves measure protonation in each assay. (UniProtKB:P07003; EcoCyc:ENZRXN-17895; PMID:6286628.) Native and reviewed annotations divide PoxB into PYR residues 1–182, FAD-binding 183–334, PP 335–530 and membrane-binding 531–572 regions. Pyruvate/TPP occupancy and flavin reduction expose the C-terminal lipid-binding region; native context describes C termini becoming solvent-accessible and proximal and lipid-mediated enhancement of flavin electron transfer. The native source places FAD and TPP sites within about 20 Å. UniProt describes a Phe465 rearrangement linked to activation. These are attributed structural/mechanistic annotations, not independently repeated residue-level assays here. Evolutionary relatedness to acetohydroxy-acid-synthase subunits and glyoxylate carboligase does not transfer their reactions to this route. (UniProtKB:P07003; EcoCyc:PYRUVOXID-MONOMER; EcoCyc:ENZRXN-17895.) Lipid activation depends on preparation and chemical identity. The 1975 abstract describes lipid depletion and reconstitution using a neutral-lipid fraction and hepta-DL-alanyldodecylamide detergent: activity recovered to 37% after acetone extraction and fully after phospholipase treatment. Q6 or Q8 restored a photoinactivated neutral-lipid preparation, whereas MK6/MK8 failed to restore and suppressed activity. These observations differ from the complete Q8 proteoliposome route. Native reports of in-vitro systems and an inhibitory monoclonal antibody remain source-qualified context; antibody identity and binding mechanism are not assigned. (PMID:1100621; EcoCyc:ENZRXN-17895.) The 1984 fatty-acid abstract identifies palmitic acid as an activating neutral-lipid component. C12–C20 acids were generally most active, with stearic and arachidic exceptions; C6–C10 compounds gave about one-third activity and C2–C5 compounds were essentially inactive. A free carboxyl group was important: corresponding alcohol, aldehyde and methyl ester were weak, and both cis/trans unsaturated forms could activate. Rapid quinone reduction depended on palmitate in the tested system. The native palmitate anion and the paper's acid naming are not an assay protonation measurement. The native long-chain class is defined as C13–C22, which is not identical to this tested C12–C20 range. (PMID:6385860; EcoCyc:REG0-7984; EcoCyc:REG0-7987; EcoCyc:Long-Chain-Fatty-Acids.) The 1984 mutant abstract describes impaired lipid activation and poor function in vivo while proteolysis could fully activate the enzyme in vitro. The engineered deletion of the final 24 residues in the 1986 abstract was active in vitro, lacked further lipid activation and Triton X-114 binding, and was inactive in vivo. The 1985 proteolysis abstract describes removal of an approximately 2 kDa alpha peptide from each subunit under pyruvate/TPP conditions, loss of the lipid-binding site and over 500-fold activation in catalytic efficiency. Native structural annotations separately describe a proteolytic Δ23 form and full-length crystals; genetic Δ24 and proteolytic Δ23 are not interchangeable constructs or evidence of obligatory native cleavage. (PMID:16593486; PMID:3527254; PMID:3902830; EcoCyc:PYRUVOXID-MONOMER; UniProtKB:P07003.) Native PoxB mutations selected in an aceEF background include poxB3 P536S, with about 15% wild-type activity and altered lipid binding, and poxB4 A467T. UniProt additionally records A533T/poxB11 and A553V/poxB14 with impaired activity and lipid response; D560P/poxB15 with normal activity; E564P/poxB16 with severe impairment and weak cleavage activation; deletions 564–572/poxB7 and 570–572/poxB8 with different activity losses; and R572G/poxB10 with reduced in-vitro/in-vivo function and a proposed membrane-binding effect. Its 549–572 deletion annotation belongs to poxB6. These are source-scoped variants, not additional wild-type catalysts. V380 substrate-specificity annotation likewise does not extend the core to 2-oxobutanoate. (EcoCyc:PYRUVOXID-MONOMER; UniProtKB:P07003.) Native PoxB kinetic slots report pyruvate Km 20 mM, 2-oxobutanoate Km 8 mM, Vmax values 447 and 26 µmol mg−1 min−1 for those respective substrates, and a pyruvate kcat of 200 s−1 from different cited preparations. Reviewed annotation separately gives nonactivated pyruvate Km 90 mM/kcat 7 s−1 and activated Km 12 mM/kcat 200 s−1. They are not one universal parameter set. Native acetylation features at Lys334, Lys351 and Lys392 carry enzyme/condition-specific abundance measurements: YfiQ/YiaC-associated log2 changes and an eight-hour versus two-hour glucose comparison. Those modification observations do not establish a causal effect on PoxB catalysis; exact slot values, experimental evidence codes and locations remain source-specific. (EcoCyc:ENZRXN-17895; EcoCyc:PYRUVOXID-MONOMER; UniProtKB:P07003.) The 1980 abstract reports methyl acetylphosphonate and acetylphosphonate inhibition competitive with pyruvate, with PoxB inhibition constants more than 1000-fold greater than those for pyruvate dehydrogenase and no inhibition of yeast pyruvate decarboxylase. Binding perturbs TPP-dependent circular dichroism and increases with lipid. The retained methyl-acetylphosphonate native structure agrees with PubChem:656481 in InChI, InChIKey, formula and negative charge. Native CPD-551 instead denotes phosphonoacetaldehyde and cannot receive the acetylphosphonate experiment by name similarity. The competing native diphosphate annotation targets TPP rather than pyruvate; its primary inhibition assay was not independently inspected, and its native HP2O7(3−) form is distinct from neutral diphosphoric acid. (PMID:6990987; EcoCyc:REG0-7981; EcoCyc:REG0-7982; EcoCyc:REG0-7983; MetaCyc:METHYL-ACETYLPHOSPHONATE; PubChem:656481; EcoCyc:PPI.) N-ethylmaleimide rapidly and completely inactivated purified PoxB in the 1982 abstract, modifying one cysteine per monomer, with protection by TPP. Methyl methanethiosulfonate affected the same sensitive cysteine but inhibited only partially. These experiments do not establish direct participation of that cysteine in catalysis. A separate abstract reports inactivation by phenylglyoxal and 2,3-butanedione, partial TPP protection, multiple modified arginines with one protected, and at least a 100-fold loss of TPP affinity after butanedione treatment. Phenylglyoxal inactivation was reversible, contradicting the native IRREVERSIBLE flag; butanedione inhibition contradicts the native positive/allosteric DIACETYL entry. (PMID:7042705; PMID:7046791; EcoCyc:REG0-7978; EcoCyc:REG0-7979; EcoCyc:REG0-7980; EcoCyc:REG0-7985.) The 2001 abstract compares isogenic PoxB-null and PDHC-null strains in glucose-minimal batch and glucose-limited chemostat conditions, including constitutive or tac-promoter PoxB expression. Replacement of PDHC by PoxB reduced growth rate by 33%, growth yield by 9–25% and carbon-conversion efficiency by 29–39%; PoxB deletion reduced these measures by 16%, 14% and 24% in the reported comparisons. Native-promoter effects differed at dilution rates 0.05 and 0.25 h−1. Acetyl-CoA-synthetase induction supports acetate reassimilation as contextual physiology, not a third core event or proof of exclusive bd-I electron flow. The native acetyl-CoA safety-valve explanation is explicitly a hypothesis. (PMID:11390679; MetaCyc:PWY-7545.) Native PoxB expression context includes RpoS control, late-exponential/early-stationary-phase maxima, induction at pH 6.0, osmotic stress, sulfometuron-methyl exposure and greater abundance on glycerol than glucose; anaerobiosis decreases expression. K12/B transcription differences, aerobic phosphate-starvation flux diversion, stationary-phase acetate production, overflow metabolism and engineered pyruvate-flux redistribution are condition-dependent source annotations. Predicted reduction of oxidative stress during phosphate starvation is not established as a direct molecular step here. The 1982 poxA mapping abstract concerns a regulatory lesion with only 10–15% PoxB activity while cells grew well; poxA is not a PoxB amino-acid substitution. Expression effects are not signed enzyme-activity edges. (EcoCyc:PYRUVOXID-MONOMER; UniProtKB:P07003; PMID:6286595.) The native bd-I complex locates hemes b558, b595 and d in CydA, with one of each in the source description. Ubiquinol feeds b558, followed by electron transfer toward the b595/d oxygen-reducing center. Purified reconstituted CydA can be reduced by ubiquinol but does not alone reduce oxygen. Native CydA topology has nine transmembrane helices with an N-terminal periplasmic and C-terminal cytoplasmic orientation and a dynamic periplasmic Q-loop between helices VI and VII. The source's older eight-helix CydB prediction coexists with the modern two-four-helix-bundle plus peripheral-helix structure; historical predictions are not silently presented as equivalent resolved structures. (EcoCyc:CYDA-MONOMER; EcoCyc:CYDB-MONOMER; EcoCyc:CYT-D-UBIOX-CPLX; UniProtKB:P0ABJ9; UniProtKB:P0ABK2.) Residue–heme assignments conflict among retained sources. Modern native prose places His19 at heme d and Glu445 at b595, with His186/Met393 at b558; older features and current predicted UniProt annotation assign His19 to b595, and an older His126 feature concerns a proposed heme-d ligand. The deposited 6RKO coordinates list CydA His19–HDD, His186–HEB and Glu445–HEB metal contacts at 2.631, 2.446 and 2.194 Å, respectively. These are deposition-specific contacts, not a resolution of every historic assignment or proof that an unlisted contact is absent. No unqualified residue–heme binding edge is asserted. (EcoCyc:CYDA-MONOMER; UniProtKB:P0ABJ9; DOI:10.2210/pdb6rko/pdb.) The 2019 primary abstract reports a 2.7 Å cryo-EM bd-I structure, the additional CydH chain, structural Q8 and proposed oxygen, water and proton pathways. The independently inspected 6RKO deposition has CydA, CydB, CydX and YnhF/CydH chains; its K12 source annotations differ from its E. coli C43 delta-bo3 expression host. Deposited nonpolymers include one UQ8, two HEB, one HDD, one OXY, four POV lipids and waters. CydB-bound structural Q8 is distinct from turnover quinone, and channel/oxygen-density interpretations do not by themselves establish in-vivo flux. The journal full body was inaccessible; deposited coordinates and metadata are not claimed to reproduce all methods. (PMID:31604309; DOI:10.2210/pdb6rko/pdb; EcoCyc:CYDB-MONOMER.) Heme names denote cofactor classes without fixing every catalytic iron oxidation state. Native heme-d prose discusses trans/cis differences, a proposed spirolactone and evidence that lactonization can be an artifact of a diol; UniProt instead selects a cis-diol chemical reference, while the 6RKO HDD component is named a cis heme-d hydroxychlorin gamma-spirolactone. Generic heme d is therefore retained without declaring these exact structures identical. The generic native heme-b drawing also does not establish the iron state of every catalytic preparation. Heme biosynthesis, catalase-HPII heme formation and unrelated hemoproteins are chemical background, not additional route steps. (MetaCyc:HEME_D; MetaCyc:Heme-b; UniProtKB:P0ABJ9; DOI:10.2210/pdb6rko/pdb.) Source-scoped CydA mutagenesis distinguishes assembly from activity. H19L/R lose b595/d and aerobic function despite assembly; H86R and H126R have no reported effect, whereas H126P loses cofactors despite assembly. H186L loses b558 and is proteolysis-sensitive. H314L changes the b/d ratio yet permits growth; H314P loses complex/hemes. M393L yields high-spin b558 with about 1% activity, while H510L has no reported effect. These variant results do not by themselves identify an axial ligand in the native structure. CydB H56L, H197L, H237L/R and H376P are annotated without effects; native D58E increases duroquinol activity especially at alkaline pH, whereas D58L lacks activity at pH 6–9. The latter assay does not directly measure the whole pyruvate route. (UniProtKB:P0ABJ9; UniProtKB:P0ABK2; EcoCyc:CYDB-MONOMER.) Additional native/reviewed protein observations retain their assay scope: 86% formylated N-terminal CydA in an isolated preparation, blocked CydB N terminus, and the 3023.74 Da formyl-Met YnhF preparation are not universal occupancy measurements. CydX single-helix topology, GFP/PhoA reporters, SecE/YidC-depletion effects, fractionation and increased expression at low oxygen or after SDS/EDTA exposure arise from separate experiments. YnhF dual-orientation reporters, chloroform extraction with lipids, aerobic/stationary-phase abundance, approximately fourfold low-oxygen increase in rich medium and glucose-to-glycerol repression do not independently demonstrate its catalytic role. Sequence conflict and frameshift cautions in the issuing protein records remain cautions, not new pathway variants. (UniProtKB:P0ABJ9; UniProtKB:P0ABK2; UniProtKB:P56100; UniProtKB:A5A618; EcoCyc:MONOMER0-2663; EcoCyc:MONOMER0-2822.) The fully inspected 2013 CydX paper used MG1655-derived deletion and tagged strains, with deletion cassettes and P1 transduction described in its methods/table 1. CydX/AppX complementation used pBAD24 overexpression with 0.2% arabinose; plasmid manipulations in ΔcydX backgrounds were handled anaerobically at 30 °C to limit suppressors and mixed colonies. Replacing the cydX ATG start codon with CAA removes normal translation initiation; this is not an experimentally tested M1Q protein merely because an annotation encodes that substitution. Wild-type sequence accessions identify the reference protein, not all these engineered materials. (PMID:23749980; UniProtKB:P56100.) Under the 2013 tested conditions, ΔcydX, ΔcydAB and ΔcydABXE strains grew more slowly, formed mixed colonies and were sensitive to beta-mercaptoethanol. CydX supplied in trans rescued growth and beta-mercaptoethanol resistance. The study found no significant hydrogen-peroxide sensitivity and only a slight hydroxylamine increase; ΔybgE behaved like wild type in the tested assays. Growth used 30 ml cultures in 250 ml flasks at 37 °C. Disk assays used 10 µl of 12 M beta-mercaptoethanol, 30% peroxide or 50% hydroxylamine and overnight incubation at 30 °C. These are conditional whole-cell phenotypes, not direct measurements of the two-event respiratory flux. (PMID:23749980.) The 2013 membrane assay followed TMPD oxidation at 611 nm with 1% TMPD and 0.16 mM ascorbate, quadruplicate measurements and correction for air autooxidation. ΔcydX membranes showed a two- to threefold reduction and complementation restored activity. The paper explicitly did not measure ubiquinol oxidase activity. C-terminal SPA-tagged CydX entered high-molecular-weight membrane complexes whose gel behavior changed after heating to 95 °C. Its purified eluate retained TMPD activity; this demonstrates association with an active preparation, not autonomous catalysis by isolated CydX. The later 2014 abstract supports a role for CydX in assembly or stability of the diheme center, leaving those alternatives distinct. (PMID:23749980; PMID:24681096.) Reciprocal 2013 affinity experiments combined CydX-SPA with CydA-6His expressed at lacZ under the cydAB promoter or CydB-6His at its native locus. Nickel, FLAG and calmodulin purification conditions and negative/background controls distinguish copurification from a universal stable native stoichiometry. Fragmentation complicated the ectopic CydA material. The CydB-His tag impaired beta-mercaptoethanol resistance despite normal aerobic growth, so that construct is not functionally identical to untagged wild type. YneM and AcrZ controls and background nickel affinity are retained; the reported potential CydA/B mass-spectrometry bands are data-not-shown observations in the body, not independently inspected spectra. (PMID:23749980.) Of fifteen tested CydX mutants, F4A, I7A, L12A and A21G failed beta-mercaptoethanol-resistance complementation; C14S restored it, arguing against the proposed essential cysteine heme-coordination role in that assay. Several highly conserved residues, including Y3, W6, A13 and E25, were dispensable by this test, and overexpression may mask some effects. Placement on one helix face is a modeling interpretation. AppX overexpression rescued ΔcydX and low-oxygen tagged preparations weakly copurified with CydA/B, supporting conditional overlap without equating AppX with CydH or replacing the modern quartet. Folding/stability, CydDC interaction and substrate-specificity hypotheses remained unresolved. The supplementary PDF request returned an HTML challenge; its tables and figures were not independently read. (PMID:23749980.) Cardiolipin activation was measured in the fully inspected 2021 paper using E. coli MB43 carrying pET17cydABX-Strep-tag, purified in DDM. Assays used Q1/DTT, 2 nM enzyme, 37 °C, pH 7.5 and 0.025% DDM. Ten micromolar bovine-heart cardiolipin approximately doubled oxygen-consumption activity and lowered apparent Q1 Km from 95 ± 16 to 35 ± 4 µM. The Sigma C1649 preparation was a lipid mixture with over 80% polyunsaturated, predominantly linoleic acyl chains. This is a conditional effect on detergent-solubilized tagged material, not proof of one exact endogenous cardiolipin species or CydH occupancy. (PMID:33850195; EcoCyc:REG0-15843.) The cardiolipin study explicitly left the effect in native membranes untested. Aurachin D at 400 nM strongly inhibited with or without cardiolipin. Its G. thermodenitrificans K1041/pSTE-cbdAB and C. glutamicum ΔctaD/pPC4-cydABDC comparisons used MK1, while E. coli GO105/pJRhisA bo3 was a distinct preparation. These experiments do not add those organisms or oxidases to the selected PoxB/Q8/bd-I route. General cardiolipin requirements in mitochondrial complexes III, IV and V are background and do not establish bd-I lipid stoichiometry. Phospholipid is itself a broad chemical class, not a single universally activating molecule. (PMID:33850195; EcoCyc:CARDIOLIPIN; EcoCyc:Phospholipids; EcoCyc:REG0-7191.) Purified E. coli and Azotobacter vinelandii bd preparations in the 2004 abstract were reversibly inhibited by nitric oxide competing with oxygen; the reported Ki was 100 ± 34 nM near 70 µM oxygen. Neither preparation showed nitric-oxide-reductase activity under the tested anaerobic reducing conditions. Whole-cell experiments in a different abstract involve Hmp mutants and overexpression; Hmp-dependent protection, oxygen conditions and KCN effects are not measurements of exclusive bd-I inhibition. The 2019 CO abstract reports reversible oxygen-competitive inhibition with Ki 0.04 ± 0.01 µM for purified bd-I; bo3 2.4 ± 0.3 µM and bd-II 0.2 ± 0.1 µM are comparators, not substituted bd-I values. (PMID:15474037; PMID:10915782; PMID:31669488; EcoCyc:REG0-12947; EcoCyc:REG0-13449.) The microcin J25 abstract reports weak dose-dependent inhibition of isolated bd-I, reactive-oxygen-species formation and partial reduction in the presence of cyanide; bo3 lacked the corresponding inhibition. Native/chemical identity identifies the 21-residue lasso peptide, not all microcins. The aurachin abstract reports inhibition by aurachin C of both bo and bd, and selective bd inhibition by aurachin D. Substrate-pulse experiments support interference with quinol oxidation rather than the oxygen reaction. Its binding/titration details for bo are not transferred to bd, and the indexed abstract is explicitly truncated. These compounds are conditional assay inhibitors, not proof of a single cellular target. (PMID:30790617; PMID:7827023; EcoCyc:REG0-13301; EcoCyc:REG0-13445; EcoCyc:REG0-13447; MetaCyc:CPD-22318.) The 2008 gramicidin-S abstract reports higher-concentration inhibition of purified bd, IC50 3.5 µM, lower maximal velocity and reduced apparent substrate affinity, but stimulation at low concentrations. Gramicidin S is a cyclic decapeptide. The native regulator instead points to the linear gramicidin A/B/C mixture and incorrectly calls S a cyclic pentadecapeptide in its background. The primary sign therefore belongs to exact gramicidin S with its dose qualification, not to the native linear class; both low-dose activation and higher-dose inhibition are preserved. (PMID:18519036; EcoCyc:REG0-9591; EcoCyc:Gramicidins.) The 1984 purified K12 cytochrome-d abstract reports Q1, menadiol and ascorbate/TMPD as assay donors, oxygen Km 0.38 µM compared with 2.9 µM for cytochrome o, and Q1-linked proteoliposome potential. Sodium azide, potassium cyanide and piericidin A inhibited with lower sensitivity than cytochrome o. The native azide structure is N3−, not the hydrogen-azide xref, while the paper used a sodium salt; potassium cyanide retains its salt identity. Earlier two-band sizes and heme/iron measurements are historical purification observations, not exclusion of small accessory chains. The 1983 preparation used Zwittergent 3-12 and reported no nonheme iron/copper. (PMID:6321507; PMID:6307994; EcoCyc:REG0-7186; EcoCyc:REG0-7187; EcoCyc:REG0-7188; EcoCyc:CPD-2841.) Hydroxylamine inhibition remains a source-attributed native annotation: its cited purification abstract does not independently supply the assay result here. Native hydroxyquinoline-N-oxide regulation has a chemical-identity conflict: the retained native/CHEBI:192375 structure is 8-hydroxyquinoline N-oxide, whereas UniProt specifies 2-heptyl-4-hydroxyquinoline N-oxide. No exact inhibition edge is assigned across those structures. Likewise the native phospholipid-activation entry is retained with preparation/mixture limits, separately from the experimentally detailed cardiolipin result. Native-only reports remain distinguishable from inspected primary experiments. (EcoCyc:REG0-7189; EcoCyc:REG0-7190; EcoCyc:CPD0-1633; EcoCyc:REG0-7191; UniProtKB:P0ABJ9; PMID:2856144.) Native bd-I context reports quinol-peroxidase activity without catalase activity, possible peroxide defense, and resistance to sulfide inhibition relative to bo. In glycerol medium, cystine stopped growth of ΔcydAB cells and a tcyP deletion relieved the defect, connecting cystine import to that phenotype. Native/reviewed hydroxyurea-resistance observations and a proposed hydroxyl-radical mechanism are context rather than direct respiratory stoichiometry. Nitric-oxide/Hmp, cystine/sulfide and peroxide findings do not establish additional detoxification reactions inside this two-event pathway. (EcoCyc:CYT-D-UBIOX-CPLX; UniProtKB:P0ABJ9; UniProtKB:P0ABK2.) Native cydAB expression is negatively regulated by Fnr, induced via ArcA/ArcB under anaerobiosis and repressed by H-NS aerobically, with maximal expression at low oxygen. Iron limitation, peroxide, DNA-supercoiling changes and nitric oxide also affect expression in the cited source contexts. These are regulatory annotations about transcription or abundance, not evidence of direct small-molecule activation of purified bd-I. GFP-tagged bd-I localization to mobile inner-membrane patches is explicitly a tagged-cell observation. No signed gene-expression edges or unqualified wild-type patch geometry are inferred without the exact regulatory originals and matching primary assays. (EcoCyc:CYT-D-UBIOX-CPLX; UniProtKB:P0ABJ9; UniProtKB:P0ABK2.) Native topology feature FTR0-1140357 for CydB residues 125–140 cites PMID:10067013, whose actual indexed title concerns psychological and obstetrical responses after fetal-sex identification. That citation is rejected as biological support. A neighboring reference, PMID:10076013, is a cytochrome-bd sequence/topology analysis, but its abstract is not a verified replacement for this exact CydB span. Its predicted CydA topology and putative His19 assignment also remain historically scoped rather than overriding later structural observations. The retained feature and its erroneous citation are not silently repaired. (EcoCyc:CYDB-MONOMER; PMID:10067013; PMID:10076013.) Support tiers are kept explicit: retained native/UniProt structured annotations support source-attributed context; most primary studies were inspected as indexed abstracts; the 2013 CydX and 2021 cardiolipin bodies and the 6RKO deposition provide the detailed construct observations stated above. Missing abstracts and failed full-text requests do not establish negative biological results. The graph preserves complete native chemistry and separate Rhea projections, conditional regulators and reference assemblies while withholding unresolved exact HQNO, acetylphosphonate/CPD-551, uncoupler and residue–heme assignments. It does not claim that one strain, lipid, inhibitor concentration or engineered construct establishes all physiological behavior. (MetaCyc:PWY-7545; PMID:23749980; PMID:33850195; DOI:10.2210/pdb6rko/pdb.) Native CydX prose separately attributes an intact-complex analysis to Chorev 2018, reporting simultaneous CydX and AppX association with CydAB as a heterotetramer. This is a source-qualified alternative assembly observation, not independently inspected primary methods or a reason to identify AppX with the modern CydH chain. Native CydH prose places it in a hydrophobic CydA cleft. Current UniProt still uses historical heterodimer/probable-accessory wording for some subunits. These source-specific assemblies and evidence strengths remain distinct from the exact native CydA/B/X/H component list. (EcoCyc:MONOMER0-2663; EcoCyc:MONOMER0-2822; EcoCyc:CYT-D-UBIOX-CPLX; UniProtKB:P0ABJ9; UniProtKB:P0ABK2; UniProtKB:P56100.) Reviewed CydA/B kinetics cite the historical purified preparation at pH 7.0 and 37 °C: Vmax values are 383, 270 and 126 µmol min−1 mg−1 for ubiquinol-1, 2,3,5,6-tetramethyl-p-phenylenediamine and N,N,N′,N′-tetramethyl-p-phenylenediamine, with respective Km values 0.1, 0.28 and 0.68 mM. These annotation-derived donor-specific values do not replace the later tagged-Q1/cardiolipin or membrane-TMPD experiments. The same reviewed source attributes 90% inhibition to 1 mM cyanide or 40 µM 2-heptyl-4-hydroxyquinoline N-oxide; that source-scoped statement does not resolve the conflicting native HQNO identity. UniProt explicitly bases displayed CydB topology on PMID:15013751 rather than the cited large-scale study PMID:15919996. Family and interaction-database annotations indicate relatedness/association, not new catalytic sufficiency. (UniProtKB:P0ABJ9; UniProtKB:P0ABK2.)

Pathway type

energy metabolism

Organism scope

• Escherichia coli NCBITaxon:562

Read the source YAML

Components and activities

Mechanistic edges

References

• MetaCyc:RXN-11496 MetaCyc:RXN-11496: MetaCyc:RXN-11496 (source version: Whole issuing native Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:PYRUVATE MetaCyc:PYRUVATE: pyruvate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:WATER MetaCyc:WATER: H2O (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:CARBON-DIOXIDE MetaCyc:CARBON-DIOXIDE: CO2 (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:ACET MetaCyc:ACET: acetate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:RXN0-5266 MetaCyc:RXN0-5266: MetaCyc:RXN0-5266 (source version: Whole issuing native Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:OXYGEN-MOLECULE MetaCyc:OXYGEN-MOLECULE: dioxygen (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:PROTON MetaCyc:PROTON: H+ (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• RHEA:27406 a ubiquinone + pyruvate + H2O => a ubiquinol + acetate + CO2 (source version: Whole Rhea RDF release 142; oriented reaction, whole participants and source-specific compartment/coefficient details inspected.)
• RHEA:40528 2 a ubiquinol + O2(in) + 4 H(+)(in) => 2 a ubiquinone + 2 H2O(in) + 4 H(+)(out) (source version: Whole Rhea RDF release 142; oriented reaction, whole participants and source-specific compartment/coefficient details inspected.)
• MetaCyc:PWY-7545 MetaCyc:PWY-7545: pyruvate to cytochrome bd oxidase electron transfer (source version: Whole issuing native Pathway XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:ENZRXN-17895 EcoCyc:ENZRXN-17895: pyruvate oxidase (source version: Whole issuing native Enzymatic-Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CYT-D-UBIOX-ENZRXN EcoCyc:CYT-D-UBIOX-ENZRXN: cytochrome bd-I ubiquinol oxidase (source version: Whole issuing native Enzymatic-Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:PYRUVOXID-CPLX EcoCyc:PYRUVOXID-CPLX: pyruvate oxidase (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:PYRUVOXID-MONOMER EcoCyc:PYRUVOXID-MONOMER: pyruvate oxidase (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CYT-D-UBIOX-CPLX EcoCyc:CYT-D-UBIOX-CPLX: cytochrome bd-I ubiquinol:oxygen oxidoreductase (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CYDA-MONOMER EcoCyc:CYDA-MONOMER: cytochrome bd-I subunit 1 (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CYDB-MONOMER EcoCyc:CYDB-MONOMER: cytochrome bd-I subunit 2 (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:MONOMER0-2663 EcoCyc:MONOMER0-2663: cytochrome bd-I accessory subunit CydX (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:MONOMER0-2822 EcoCyc:MONOMER0-2822: cytochrome bd-I accessory subunit CydH (source version: Whole issuing native Protein XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• UniProtKB:P07003 Pyruvate dehydrogenase [ubiquinone] (source version: Whole UniProt JSON, entry version 192; evidence codes and cited experimental scopes retained.)
• MetaCyc:Heme-b MetaCyc:Heme-b: heme b (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:HEME_D MetaCyc:HEME_D: heme d (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-12947 EcoCyc:REG0-12947: EcoCyc:REG0-12947 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:NITRIC-OXIDE EcoCyc:NITRIC-OXIDE: nitric oxide (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-13301 EcoCyc:REG0-13301: EcoCyc:REG0-13301 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD-22318 EcoCyc:CPD-22318: microcin J25 (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-13445 EcoCyc:REG0-13445: EcoCyc:REG0-13445 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD-7733 EcoCyc:CPD-7733: aurachin C (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-13447 EcoCyc:REG0-13447: EcoCyc:REG0-13447 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD-15909 EcoCyc:CPD-15909: aurachin D (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-13449 EcoCyc:REG0-13449: EcoCyc:REG0-13449 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CARBON-MONOXIDE EcoCyc:CARBON-MONOXIDE: carbon monoxide (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-15843 EcoCyc:REG0-15843: EcoCyc:REG0-15843 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:CARDIOLIPIN MetaCyc:CARDIOLIPIN: a cardiolipin (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PMID:33850195 Cardiolipin enhances the enzymatic activity of cytochrome bd and cytochrome bo3 solubilized in dodecyl-maltoside. (source version: Full primary article XML inspected, PMC8044227; construct, detergent, lipid mixture and assay limitations retained.)
• EcoCyc:REG0-7186 EcoCyc:REG0-7186: EcoCyc:REG0-7186 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD-2841 EcoCyc:CPD-2841: azide (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7187 EcoCyc:REG0-7187: EcoCyc:REG0-7187 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD-7082 EcoCyc:CPD-7082: potassium cyanide (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7188 EcoCyc:REG0-7188: EcoCyc:REG0-7188 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD0-1233 EcoCyc:CPD0-1233: piericidin A (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7189 EcoCyc:REG0-7189: EcoCyc:REG0-7189 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:HYDROXYLAMINE EcoCyc:HYDROXYLAMINE: hydroxylamine (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7191 EcoCyc:REG0-7191: EcoCyc:REG0-7191 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:Phospholipids EcoCyc:Phospholipids: a phospholipid (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7978 EcoCyc:REG0-7978: EcoCyc:REG0-7978 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:PHENYLGLYOXAL EcoCyc:PHENYLGLYOXAL: phenylglyoxal (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PMID:7046791 Role of arginine in the binding of thiamin pyrophosphate to Escherichia coli pyruvate oxidase. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• EcoCyc:REG0-7979 EcoCyc:REG0-7979: EcoCyc:REG0-7979 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:METHYLMETHANETHIOSULFONATE EcoCyc:METHYLMETHANETHIOSULFONATE: methylmethanethiosulfonate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7980 EcoCyc:REG0-7980: EcoCyc:REG0-7980 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:N-ETHYLMALEIMIDE EcoCyc:N-ETHYLMALEIMIDE: N-ethylmaleimide (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7982 EcoCyc:REG0-7982: EcoCyc:REG0-7982 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:METHYL-ACETYLPHOSPHONATE EcoCyc:METHYL-ACETYLPHOSPHONATE: methyl-acetylphosphonate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7983 EcoCyc:REG0-7983: EcoCyc:REG0-7983 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:PPI EcoCyc:PPI: diphosphate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7984 EcoCyc:REG0-7984: EcoCyc:REG0-7984 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:PALMITATE EcoCyc:PALMITATE: palmitate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7986 EcoCyc:REG0-7986: EcoCyc:REG0-7986 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7987 EcoCyc:REG0-7987: EcoCyc:REG0-7987 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:Long-Chain-Fatty-Acids EcoCyc:Long-Chain-Fatty-Acids: a long-chain fatty acid (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7985 EcoCyc:REG0-7985: EcoCyc:REG0-7985 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PMID:18519036 Gramicidin S identified as a potent inhibitor for cytochrome bd-type quinol oxidase. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• EcoCyc:PWY-7545 EcoCyc:PWY-7545: pyruvate to cytochrome bd oxidase electron transfer (source version: Whole issuing native Pathway XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CCO-IN EcoCyc:CCO-IN: in (source version: Whole issuing native cco XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CCO-OUT EcoCyc:CCO-OUT: out (source version: Whole issuing native cco XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:RXN0-5244 MetaCyc:RXN0-5244: MetaCyc:RXN0-5244 (source version: Whole issuing native Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:RXN0-6375 MetaCyc:RXN0-6375: MetaCyc:RXN0-6375 (source version: Whole issuing native Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:TRANS-RXN0-237 MetaCyc:TRANS-RXN0-237: MetaCyc:TRANS-RXN0-237 (source version: Whole issuing native Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:RXN0-5265 MetaCyc:RXN0-5265: MetaCyc:RXN0-5265 (source version: Whole issuing native Reaction XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• RHEA:29170 RHEA:29170 whole retained reaction resource (source version: Whole Rhea RDF release 142; oriented reaction, whole participants and source-specific compartment/coefficient details inspected.)
• RHEA:30251 RHEA:30251 whole retained reaction resource (source version: Whole Rhea RDF release 142; oriented reaction, whole participants and source-specific compartment/coefficient details inspected.)
• PathBank:SMP0002099 Frozen PathBank PW002087 / SMP0002099 pyruvate-to-cytochrome-bd electron-transfer diagram (source version: Frozen whole BioPAX member PW002087.owl with retained parent ZIP provenance. Four diagram events/15 sides; current webpage labels are a separate observation.)
• MetaCyc:Ubiquinones MetaCyc:Ubiquinones: a ubiquinone (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:Ubiquinols MetaCyc:Ubiquinols: a ubiquinol (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PMID:6367818 Reconstitution of the membrane-bound, ubiquinone-dependent pyruvate oxidase respiratory chain of Escherichia coli with the cytochrome d terminal oxidase. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:1850294 Properties of the two terminal oxidases of Escherichia coli. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• UniProtKB:A5A618 Uncharacterized protein YnhF (source version: Whole UniProt JSON, entry version 79; evidence codes and cited experimental scopes retained.)
• PMID:6307994 The purification and characterization of the cytochrome d terminal oxidase complex of the Escherichia coli aerobic respiratory chain. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:6321507 Terminal oxidases of Escherichia coli aerobic respiratory chain. II. Purification and properties of cytochrome b558-d complex from cells grown with limited oxygen and evidence of branched electron-carrying systems. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:31604309 Active site rearrangement and structural divergence in prokaryotic respiratory oxidases. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:6286628 Role of the divalent metal cation in the pyruvate oxidase reaction. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:1100621 Reactivation of the lipid-depleted pyruvate oxidase system from Escherichia coli with cell envelope neutral lipids. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:6385860 Reconstitution of the lipid-depleted pyruvate oxidase system of Escherichia coli: the palmitic acid effect. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:16593486 An Escherichia coli mutant deficient in pyruvate oxidase activity due to altered phospholipid activation of the enzyme. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:3527254 In vivo function of Escherichia coli pyruvate oxidase specifically requires a functional lipid binding site. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:3902830 Characterization of the alpha-peptide released upon protease activation of pyruvate oxidase. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:6990987 Phosphonate analogues of pyruvate. Probes of substrate binding to pyruvate oxidase and other thiamin pyrophosphate-dependent decarboxylases. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• EcoCyc:REG0-7981 EcoCyc:REG0-7981: EcoCyc:REG0-7981 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• MetaCyc:METHYL-ACETYLPHOSPHONATE MetaCyc:METHYL-ACETYLPHOSPHONATE: methyl-acetylphosphonate (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PubChem:656481 Acetyl(methoxy)phosphinate (source version: Whole issuing property response; separate extended response preserves InChI, formula and charge verification against native original.)
• PMID:7042705 Identification of an active site cysteine residue in Escherichia coli pyruvate oxidase. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:11390679 Pyruvate oxidase contributes to the aerobic growth efficiency of Escherichia coli. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:6286595 Mapping nonselectable genes of Escherichia coli by using transposon Tn10: location of a gene affecting pyruvate oxidase. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• UniProtKB:P0ABJ9 Cytochrome bd-I ubiquinol oxidase subunit 1 (source version: Whole UniProt JSON, entry version 153; evidence codes and cited experimental scopes retained.)
• UniProtKB:P0ABK2 Cytochrome bd-I ubiquinol oxidase subunit 2 (source version: Whole UniProt JSON, entry version 142; evidence codes and cited experimental scopes retained.)
• DOI:10.2210/pdb6rko/pdb 6RKO: Cryo-EM structure of cytochrome bd-I oxidase from Escherichia coli (source version: Whole deposited mmCIF retrieved 2026-10-12; entity, host, component and struct_conn fields inspected. Not a claim of journal full-methods access.)
• UniProtKB:P56100 Cytochrome bd-I ubiquinol oxidase subunit X (source version: Whole UniProt JSON, entry version 147; evidence codes and cited experimental scopes retained.)
• PMID:23749980 The Escherichia coli CydX protein is a member of the CydAB cytochrome bd oxidase complex and is required for cytochrome bd oxidase activity. (source version: Full primary article HTML inspected, PMC3754557, including methods/table 1/body figure captions. Supplement request returned HTML challenge; supplement not inspected.)
• PMID:24681096 Subunit CydX of Escherichia coli cytochrome bd ubiquinol oxidase is essential for assembly and stability of the di-heme active site. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• EcoCyc:CARDIOLIPIN EcoCyc:CARDIOLIPIN: a cardiolipin (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PMID:15474037 Interaction of the bacterial terminal oxidase cytochrome bd with nitric oxide. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:10915782 Flavohemoglobin Hmp affords inducible protection for Escherichia coli respiration, catalyzed by cytochromes bo' or bd, from nitric oxide. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:31669488 In the respiratory chain of Escherichia coli cytochromes bd-I and bd-II are more sensitive to carbon monoxide inhibition than cytochrome bo3. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:30790617 Microcin J25 inhibits ubiquinol oxidase activity of purified cytochrome bd-I from Escherichia coli. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:7827023 New inhibitors of the quinol oxidation sites of bacterial cytochromes bo and bd. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• MetaCyc:CPD-22318 MetaCyc:CPD-22318: microcin J25 (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-9591 EcoCyc:REG0-9591: EcoCyc:REG0-9591 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:Gramicidins EcoCyc:Gramicidins: a gramicidin (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:REG0-7190 EcoCyc:REG0-7190: EcoCyc:REG0-7190 (source version: Whole issuing native Regulation XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• EcoCyc:CPD0-1633 EcoCyc:CPD0-1633: hydroxyquinoline N oxide (source version: Whole issuing native Compound XML; PGDB 27.0; retrieved 2026-10-12. Native citations are not claims of full-paper inspection.)
• PMID:2856144 Purification and properties of two terminal oxidase complexes of Escherichia coli aerobic respiratory chain. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:10067013 Psychological and obstetrical responses of mothers following antenatal fetal sex identification. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)
• PMID:10076013 Sequence analysis of cytochrome bd oxidase suggests a revised topology for subunit I. (source version: Europe PMC core indexed metadata and abstract where present; full paper not inspected. Abstract evidence only.)