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PubMed1975

Aggregation states and catalytic properties of the multienzyme complex catalyzing the initial steps of pyrimidine biosynthesis in rat liver.

Glutamine-dependent carbamoyl-phosphate synthetase was purified about 2100-fold from the cytosol of rat liver using 30% (v/v) dimethyl sulfoxide and 5% (w/v) glycerol as stabilizers. Throughout the purification, aspartate transcarbamylase and dihydroorotase, the second and third enzymes of pyrimidine biosynthesis, were copurified with the synthetase. These three enzymes sedimented as a single peak with a sedimentation coefficient of 27 S in sucrose gradients containing the stabilizers, indicating their existence as a multienzyme complex. The aggregation states of the complex were analyzed by sucrose gradient centrifugation under conditions approximating those used for enzymatic assay and correlated with the kinetic properties of the synthetase. In the presence of 10% glycerol and 10 mM MgATP(2-) at 18 degrees, the synthetase showed high activity and the three enzymes sedimented as a single peak with a coefficient of 25 S. The three enzymes also existed as a complex with the same coefficient when 50 muM PP-ribose-P was added in place of MgATP(2-), the sedimentation coefficient of the complex shifted to 28 S, indicating alteration in its molecular shape, rather than size. With 10% glycerol alone, the complex partially dissociated and the synthetase activity appeared in three peaks with coefficients of 26, 19, and 9 S (carbamoyl-phosphate synthetases (CPSase) a, b, and c, respectively). CPSases a, b, and c, thus obtained, were all sensitive to regulation by UTP and PP-ribose-P, but they differed MgATP(2-) (5.1, 4.8, AND 1.7 mM for CPSases a and b, and the enzyme within the original complex, respectively) and in their sensitivities to effectors. These results suggest that the aggregation may modify the catalytic and regulatory properties of the synthetase; Attempts to reassociate the components were unsuccessful.

Amidohydrolases↗

PubMed1976

The tentative identification in Escherichia coli of a multienzyme complex with glycolytic activity.

Penicillin spheroplasts of Escherichia coli were ruptured osmotically, by freezing and thawing, or mechanically. Differential centrifugation sedimented 20-30% of the glycolytic enzymes without increasing their specific activities. There was, however, evidence of distinct groups of sedimenting enzymes; growth on different carbon sources could influence the distribution. Sucrose gradient studies gave no evidence of enzyme association but provided estimations of the molecular weight of each enzyme which were close to those subsequently observed on gel filtration. Using the determined molecular weight and a literature value for specific activity, the measured activity ratio of the enzymes was compared with that expected from an equimolar mixture. All values agreed within a factor of five, except for hexokinase. The relative roles of hexokinase and phosphotransferase in E. coli are briefly considered. An equimolar multienzyme aggregate of all the enzymes of glycolysis would have a molecular weight of about 1.6 X 10(6). Chromatography on a Biogel column yielded one fraction, corresponding to a molecular weight of 1.6 X 10(6), which contained a proportion of all the glycolytic enzyme studied; the remaining portion of each enzyme activity was eluted from the column at the position expected from its individual molecular weight. The fraction of mol. wt 1 600 000 was tested for complete glycolysis pathway activity and found not to be different from a reconcentrated mixture of the separated enzymes. Both the eluted and the reconstructed systems showed unexpected activity changes at different protein concentrations. The specific radioactivity of pyruvate formed by these systems from [14C]glucose 6-phosphate was reduced by the presence of unlabelled 3-phosphoglycerate, but by less than would have been expected had the latter been able to participate fully in glycolytic activity. This result indicates that these preparations were capable of selectivity compartmenting glycolytic intermediates. Electron microscope investigation of both systems showed large numbers of regular 30 nm diameter particles which, on disruption, appeared to be composed of smaller units: it is possible that these particles may have been aggregates containing glycolytic enzymes. The possible advantages of a glycolytic multienzyme complex are briefly discussed.

Carbohydrate Epimerases↗

PubMed1991

Molecular interaction of the proteasome (multicatalytic proteinase). Evidence that the proteasome is not a constituent of the '26 S' multienzyme complex.

On the basis of recent reports that suggested that proteasomes, via an ATP-dependent process, become integral components of a '26 S' complex possessing 3-carboxypropionyl-Leu-Leu-Val-Tyr 4-methylcoumarin-7-ylamide-hydrolysing activity, we have investigated the molecular interaction of proteasomes in ATP-stabilized fraction II (proteins absorbed on DEAE-matrix and eluted with 0.5 M-KCl) of rabbit reticulocytes and mouse liver. Analysis of the various extracts by (NH4)2SO4 fractionation, velocity-gradient centrifugation, non-denaturing PAGE and SDS/PAGE and immunoblotting with proteasome-specific antisera failed to identify the proteasome as part of a higher-molecular-mass '26 S' multienzyme complex. In all instances proteasomes are identified in their 'free' 650 kDa '20 S' form. In addition to the proteasome and independent of the presence of MgATP, we isolated a high-molecular-mass proteinase whose electrophoretic migration behaviour and sedimentation rate correspond to that of the previously described '26 S' proteinase. This '26 S' proteinase possesses a strong 3-carboxypropionyl-Leu-Leu-Val-Tyr 4-methylcoumarin-7-ylamide-hydrolysing activity and is composed of several non-identical polypeptides in the molecular-mass range 20-150 kDa. Despite its similarity to proteasomal enzyme activity, protein analysis and immunoblotting experiments demonstrate that neither the intact proteasome nor subunits thereof are components of the '26 S' proteinase complex.

Amino Acid Sequence↗

PubMed1976

Evidence for two lipoic acid residues per lipoate acetyltransferase chain in the pyruvate dehydrogenase multienzyme complex of Escherichia coli.

The reaction of two maleimides, N-ethylmaleimide and bis-(N-maleimidomethyl) ether, with the pyruvate dehydrogenase multienzyme complex of Escherichia coli in the presence of the substrate, pyruvate, was examined. In both cases, the reaction was demonstrated to be almost exclusively with the lipoate acetyltransferase component, and evidence is presented to show that the most likely sites of reaction are the lipoic acid residues covalently bound to this component. With both reagents the stoicheiometry of the reaction was measured: 2 mol of reagent reacted with each polypeptide chain of lipoate acetyltransferase, implying that each chain bears two functionally active lipolic acid residues. This observation can be reconciled with previous determinations of the lipoic acid content of the complex by allowing for the variability of the subunit polypeptide-chain ratio that can be demonstrated for this multimeric enzyme.

Acetyltransferases↗

PubMed1978

Mechanism of action of the pyruvate dehydrogenase multienzyme complex from Escherichia coli.

The extent of cooperativity among the polypeptide chain components in the overall reaction catalyzed by the pyruvate dehydrogenase multienzyme complex from Escherichia coli has been studied. Selective inactivation of the pyruvate dehydrogenase component with thiamin thiazolone pyrophosphate demonstrates that no cooperativity between this component and the overall catalytic reaction occurs: the amount of overall complex activity is directly proportional to the fraction of active pyruvate dehydrogenase component. The transacetylase component has two lipoic acid residues on each of its polypeptide chains that can be modified by N-[(3)H]ethylmaleimide in the presence of pyruvate and thiamin pyrophosphate. The kinetics of the loss of overall complex activity due to modification of the lipoyl residues on the transacetylase component by maleimide reagents shows that not all lipoic acids are coupled into the overall catalytic reaction and that acyl-group and electron pair transfer involving two or more lipoic acids per catalytic cycle must occur. Finally, full complex activity is found when only half the normal flavin content is present. The results indicate that extensive communication among lipoic acids in acyl-group and electron pair transfer must exist in the normal catalytic mechanism. These results are consistent with the average distances between catalytic sites measured by energy transfer experiments.

Escherichia coli↗

PubMed1990

The tryptophan synthase multienzyme complex: exploring structure-function relationships with X-ray crystallography and mutagenesis.

The bifunctional tryptophan synthase alpha 2 beta 2 complex that catalyzes the final two reactions in tryptophan biosynthesis is a classic example of a multienzyme complex that "channels" a metabolic intermediate (indole) between two active sites. The three-dimensional structure of the alpha 2 beta 2 complex from Salmonella typhimurium reveals that the four polypeptide subunits are arranged in an extended alpha beta beta alpha order forming a complex 150 A long. The active sites of the neighboring alpha and beta subunits are separated by about 30 A and appear to be connected by a tunnel, which may facilitate the intramolecular transfer of indole. The active site of the alpha subunit, which is centrally located near one end of an eight-fold alpha/beta barrel structure, contains the sites of most of the missense mutations which were identified as key residues by Yanofsky and colleagues in early genetic studies. Site-directed mutagenesis is being used to replace residues found in the active sites of the alpha and beta subunits in order to probe the mechanism of catalysis. Recombinant DNA technology should also be useful in analyzing protein-protein interaction, protein folding and the channeling phenomenon.

Crystallography↗

PubMed1991

Two lipoyl domains in the dihydrolipoamide acetyltransferase chain of the pyruvate dehydrogenase multienzyme complex of Streptococcus faecalis.

A fragment of DNA incorporating the gene, pdhC, that encodes the dihydrolipoamide acetyltransferase (E2) chain of the pyruvate dehydrogenase multienzyme complex of Streptococcus faecalis was cloned and a DNA sequence of 2360 bp was determined. The pdhC gene (1620 bp) corresponds to an E2 chain of 539 amino acid residues, Mr 56,466, comprising two lipoyl domains, a peripheral subunit-binding domain and an acetyltransferase domain, linked together by regions of polypeptide chain rich in alanine, proline and charged amino acids. The S. faecalis E2 chain differs in the number of its lipoyl domains from the E2 chains of all bacterial pyruvate dehydrogenase complexes hitherto described.

Acetyltransferases↗

PubMed1990

Further evidence for direct interaction of pyruvate dehydrogenase multienzyme complex with citric acid cycle based on nonlinearity of hill plots in presence of C2 and C4 substrate analogues.

1. Mammalian pyruvate dehydrogenase multienzyme complex (PDC) is measured with two different optical assays: (i) formation of p-nitro-acetanilid with arylamine-acetyltransferase and (ii) NAD reduction. 2. It is found that in contrast to the NAD assay system (ii) the coupled system (i) exhibits cooperativity with a Hill coefficient n = 3 over the whole range of substrate concentration. 3. The cooperative behaviour can be modified by presence of dichloroacetate (n = 2) and acetoin (n = 1----3). From additional measurements of PDC activity with toluene permeabilized mitochondria of fed and starved rats it is concluded that PDC activity in vivo is modified by changes in enzyme enzyme aggregation and interaction beside the known phosphorylation dephosphorylation mechanism.

Animals↗

PubMed1990

Slow-binding inhibition of the Escherichia coli pyruvate dehydrogenase multienzyme complex by acetylphosphinate.

The pyruvate analogue acetylphosphinate (CH3-CO-PO2H2) inhibits the pyruvate dehydrogenase component (E1) of the Escherichia coli pyruvate dehydrogenase multienzyme complex in a time-dependent process with biphasic reaction kinetics. The formation of an initial, rapidly reversible enzyme-inhibitor complex (EI) with an apparent Ki of 0.12 +/- 0.025 microM is followed by the conversion to a tighter complex (EI) at a maximal rate of k3 = 0.87 +/- 0.34 min-1. The inhibition is reversible (dissociation rate constant k4 = 0.038 +/- 0.002 min-1), requires the presence of the cofactors thiamin pyrophosphate and Mg2+, and is competitive with regard to pyruvate. The microscopic rate constants give a value of 5 nM for the overall dissociation constant [Ki = [E] [I]/[( EI] + [EI]) = Kik4/(k3 + k4)] compared with values of 10 and 3.5 nM obtained by steady-state methods. Thus acetylphosphinate binds by 5 orders of magnitude more tightly to pyruvate dehydrogenase than does pyruvate (Km = 0.35 mM). Acetylphosphinate also affects the pyruvate dehydrogenase complex fluorescence when excited at 290 nm in a time-dependent manner with a maximal rate constant of 0.99 min-1, suggesting a conformational change in the enzyme complex as the slow step in conversion of EI to EI (k3). All these features taken together suggest that the interaction of the pyruvate dehydrogenase with acetylphosphinate involves the formation of a thiamin pyrophosphate-acetylphosphinate adduct that resembles the normal reaction intermediate, 2-(1-carboxy-1-hydroxyethyl)thiamin pyrophosphate (alpha-lactylthiamin pyrophosphate).

Escherichia coli↗

PubMed1992

Sequences directing dihydrolipoamide dehydrogenase (E3) binding are located on the 2-oxoglutarate dehydrogenase (E1) component of the mammalian 2-oxoglutarate dehydrogenase multienzyme complex.

Sequences located in the N-terminal region of the high M(r) 2-oxoglutarate dehydrogenase (E1) enzyme of the mammalian 2-oxoglutarate dehydrogenase multienzyme complex (OGDC) exhibit significant similarity with corresponding sequences from the lipoyl domains of the dihydrolipoamide acetyltransferase (E2) and protein X components of eukaryotic pyruvate dehydrogenase complexes (PDCs). Two additional features of this region of E1 resemble lipoyl domains: (i) it is readily released by trypsin, generating a small N-terminal peptide with an apparent M(r) value of 10,000 and a large stable 100,000 M(r) fragment (E1') and (ii) it is highly immunogenic, inducing the bulk of the antibody response to intact E1. This 'lipoyl-like' domain lacks a functional lipoamide group. Selective but extensive degradation of E1 with proteinase Arg C or specific conversion of E1 to E1' with trypsin both cause loss of overall OGDC function although the E1' fragment retains full catalytic activity. Removal of this small N-terminal peptide promotes the dissociation of dihydrolipoamide dehydrogenase (E3) from the E2 core assembly and also affects the stability of E1 interaction. Thus, structural roles which are mediated by a specific gene product, protein X in PDC and possibly also the E2 subunit, are performed by similar structural elements located on the E1 enzyme of the OGDC.

Amino Acid Sequence↗

PubMed1992

Interaction of avidin with the lipoyl domains in the pyruvate dehydrogenase multienzyme complex: three-dimensional location and similarity to biotinyl domains in carboxylases.

Avidin can form intermolecular cross-links between particles of the pyruvate dehydrogenase multienzyme complex from various sources. Avidin does this by binding to lipoic acid-containing regions of the dihydrolipoamide acetyltransferase polypeptide chains that comprise the structural core of the complex. It is inferred that the lipoyl domains of the acetyltransferase chain extend outwards from the interior of the enzyme particle, interdigitating between the subunits of the other two enzymes bound peripherally in the assembled structure, with the lipoyl-lysine residues capable of reaching to within at least 1-2 nm of the outer surface of the enzyme complex (diameter ca. 37 nm). The distribution of enzymic activities between different domains of the dihydrolipoamide acetyltransferase chain implies that considerable movement of the lipoyl domains is a feature of the catalytic activity of the enzyme complex. There is evidence that the lipoyl domain of the 2-oxo acid dehydrogenase complexes is similar in structure to a domain that binds the cofactor biotin, also in amide linkage with a specific lysine residue, in the biotin-dependent class of carboxylases.

Amidohydrolases↗

PubMed1984

Inhibition of pyruvate dehydrogenase multienzyme complex from Escherichia coli with a radiolabeled bifunctional arsenoxide: evidence for an essential histidine residue at the active site of lipoamide dehydrogenase.

Incubation of pyruvate dehydrogenase multienzyme complex (PD complex) from Escherichia coli with thiamin pyrophosphate, pyruvate, coenzyme A, Mg2+, and the radiolabeled bifunctional arsenoxide p-[(bromoacetyl)-amino]phenyl arsenoxide (BrCH214CONHPhAsO) led to the irreversible loss of lipoamide dehydrogenase (E3) activity. The mode of inactivation occurred by initial "anchoring" of the reagent via its -AsO group to reduced lipoyl residues on lipoate acetyltransferase (E2) (generated by substrates) followed by the delivery of the BrCH214CO- moiety into the active site of E3 where an irreversible alkylation ensued [Stevenson, K. J., Hale, G., & Perham, R. N. (1978) Biochemistry 17, 2189]. To account for nonspecific alkylations, not mediated by this delivery process, control experiments were conducted in which the radiolabeled bifunctional reagent was incubated with PD complex in the absence of substrates. E3 subunits were isolated from inhibited and control PD complexes by chromatography on hydroxylapatite in the presence of 8 M urea. Acid hydrolysis of the alkylated E3 and control E3 samples produced radiolabeled carboxymethylated amino acids that were identified and quantitated by high-voltage electrophoresis and amino acid/radiochemical analysis. The inhibited sample contained N3-(carboxymethyl)histidine and a small amount of S-(carboxymethyl)cysteine. These residues were not present in significant amounts in the controls. The loss of 81% of E3 activity correlated with the alkylation of about 0.7 residue of histidine and 0.1 residue of cysteine per mol of E3.

Alkylation↗

PubMed1990

Interactions of lipoyl domains with the E1p subunits of the pyruvate dehydrogenase multienzyme complex from Escherichia coli.

Equilibrium binding experiments were carried out with lipoyl domains and the pyruvate decarboxylase [pyruvate dehydrogenase (lipoamide), E1p, EC 1.2.4.1)] component of the pyruvate dehydrogenase multienzyme complex of Escherichia coli. The dissociation constant (Ks) was estimated to be not less than 0.3 mM, exceeding the Km value (33 microM) for reductive acetylation of the domains by an order of magnitude. Thus, the lipoyl domain, which is required to promote reductive acetylation of the lipoyl group, does not appear to do this simply by enhancing the binding to E1p. The difference between Ks and Km suggests that the formation and release of reductively acetylated lipoyl domains from the enzyme may be a relatively rapid step in the mechanism.

Escherichia coli↗

PubMed1981

Intramolecular coupling of active sites in the pyruvate dehydrogenase multienzyme complexes from bacterial and mammalian sources.

A simple method was developed for assessing the intramolecular coupling of active sites in the lipoate acetyltransferase (E2) component of the pyruvate dehydrogenase multienzyme complexes from Escherichia coli, Bacillus stearothermophilus and ox heart and pig heart mitochondria. Samples of enzyme complex were prepared in which the pyruvate decarboxylase (E1) component was selectively and partly inhibited by treatment with increasing amounts of a transition-state analogue, thiamin thio-thiazolone pyrophosphate. The fraction of the E2 component acetylated by incubation with [2-14C] pyruvate, in the absence of CoA, was determined for each sample of partly inhibited enzyme and was found in all cases to exceed the fraction of overall complex activity remaining. This indicated the potential for transacetylation reactions among the lipoic acid residues within the E2 core. A graphic presentation of the data allowed comparison of the active-site coupling in the various enzymes, which may differ in their lipoic acid content (one or two residues per E2 chain). It is clear that active-site coupling is a general property of pyruvate dehydrogenase complexes of octahedral and icosahedral symmetries, the large numbers of subunits in each E2 core enhancing the effect.

Acetylation↗

PubMed1990

Cloning and sequence analysis of the genes encoding the alpha and beta subunits of the E1 component of the pyruvate dehydrogenase multienzyme complex of Bacillus stearothermophilus.

A 4175-bp EcoRI fragment of DNA that encodes the alpha and beta chains of the pyruvate dehydrogenase (lipoamide) component (E1) of the pyruvate dehydrogenase multienzyme complex of Bacillus stearothermophilus has been cloned in Escherichia coli. Its nucleotide sequence was determined. Open reading frames (pdhA, pdhB) corresponding to the E1 alpha subunit (368 amino acids, Mr 41,312, without the initiating methionine residue) and E1 beta subunit (324 amino acids, Mr 35,306, without the initiating methionine residue) were identified and confirmed with the aid of amino acid sequences determined directly from the purified polypeptide chains. The E1 beta gene begins just 3 bp downstream from the E1 alpha stop codon. It is followed, after a longer gap of 73 bp, by the start of another but incomplete open reading frame that, on the basis of its known amino acid sequence, encodes the dihydrolipoyl acetyltransferase (E2) component of the complex. All three genes are preceded by potential ribosome-binding sites and the gene cluster is located immediately downstream from a region of DNA showing numerous possible promoter sequences. The E1 alpha and E1 beta subunits of the B. stearothermophilus pyruvate dehydrogenase complex exhibit substantial sequence similarity with the E1 alpha and E1 beta subunits of pyruvate and branched-chain 2-oxo-acid dehydrogenase complexes from mammalian mitochondria and Pseudomonas putida. In particular, the E1 alpha chain contains the highly conserved sequence motif that has been found in all enzymes utilizing thiamin diphosphate as cofactor.

Acetyltransferases↗

PubMed1987

Segmental structure and protein domains in the pyruvate dehydrogenase multienzyme complex of Escherichia coli. Genetic reconstruction in vitro and 1H-n.m.r. spectroscopy.

A deletion in vitro can be made in the aceEF-lpd operon encoding the pyruvate dehydrogenase multienzyme complex of Escherichia coli, which causes deletion of two of the three homologous lipoyl domains that comprise the N-terminal half of each dihydrolipoamide acetyltransferase (E2p) polypeptide chain. An active complex is still formed and 1H-n.m.r. spectroscopy of this modified complex revealed that many of the unusually sharp resonances previously attributed to conformationally mobile segments in the wild-type E2p polypeptide chains had correspondingly disappeared. A further deletion was engineered in the long (alanine + proline)-rich segment of polypeptide chain that linked the one remaining lipoyl domain to the C-terminal half of the E2p chain. 1H-n.m.r. spectroscopy of the resulting enzyme complex, which was also active, revealed a further corresponding loss in the unusually sharp resonances observed in the spectrum. These experiments strongly support the view that the sharp resonances derive, principally at least, from the three long (alanine + proline)-rich sequences which separate the three lipoyl domains and link them to the C-terminal half of the E2p chain. Closer examination of the 400 MHz 1H-n.m.r. spectra of the wild-type and restructured complexes, and of the products of limited proteolysis, revealed another sharp but smaller resonance. This was tentatively attributed to another, but smaller, (alanine + proline)-rich sequence that separates the dihydrolipoamide dehydrogenase-binding domain from the inner core domain in the C-terminal half of the E2p chain. If this sequence is also conformationally flexible, it may explain previous fluorescence data which suggest that dihydrolipoamide dehydrogenase bound to the enzyme complex is quite mobile. The acetyltransferase active site in the E2p chain was shown to reside in the inner core domain, between residues 370 and 629.

Acetyltransferases↗

PubMed1992

Three-dimensional solution structure of the E3-binding domain of the dihydrolipoamide succinyltransferase core from the 2-oxoglutarate dehydrogenase multienzyme complex of Escherichia coli.

The three-dimensional solution structure of a 51-residue synthetic peptide comprising the dihydrolipoamide dehydrogenase (E3)-binding domain of the dihydrolipoamide succinyltransferase (E2) core of the 2-oxoglutarate dehydrogenase multienzyme complex of Escherichia coli has been determined by nuclear magnetic resonance spectroscopy and hybrid distance geometry-dynamical simulated annealing calculations. The structure is based on 630 approximate interproton distance and 101 torsion angle (phi, psi, chi 1) restraints. A total of 56 simulated annealing structures were calculated, and the atomic rms distribution about the mean coordinate positions for residues 12-48 of the synthetic peptide is 1.24 A for the backbone atoms, 1.68 A for all atoms, and 1.33 A for all atoms excluding the six side chains which are disordered at chi 1 and the seven which are disordered at chi 2; when the irregular partially disordered loop from residues 31 to 39 is excluded, the rms distribution drops to 0.77 A for the backbone atoms, 1.55 A for all atoms, and 0.89 A for ordered side chains. Although proton resonance assignments for the N-terminal 11 residues and the C-terminal 3 residues were obtained, these two segments of the polypeptide are disordered in solution as evidenced by the absence of nonsequential nuclear Overhauser effects. The solution structure of the E3-binding domain consists of two parallel helices (residues 14-23 and 40-48), a short extended strand (24-26), a five-residue helical-like turn, and an irregular (and more disordered) loop (residues 31-39). This report presents the first structure of an E3-binding domain from a 2-oxo acid dehydrogenase complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Acyltransferases↗

PubMed1984

NAD-dependent, PQQ-containing methanol dehydrogenase: a bacterial dehydrogenase in a multienzyme complex.

Cell-free extracts of methanol-grown Nocardia sp. 239 only show significant dye-linked methanol-oxidizing activity when NAD+ is added to the assay mixture. This activity resides in a multienzyme complex which could be resolved into 3 components, namely the methanol dehydrogenase, NAD-dependent aldehyde dehydrogenase and NADH dehydrogenase. In its dissociated form, the methanol dehydrogenase no longer shows dye reduction and although rises in the absorbance values around 340 nm are seen on addition of methanol plus NAD+ to the enzyme, this is not due to NADH production. However, dye reduction (NAD dependent) could be restored on incubating methanol dehydrogenase with the corresponding NADH dehydrogenase, obtained from the enzyme complex. It is concluded that this novel methanol dehydrogenase transfers the reducing equivalents, derived from methanol, directly to its associated NADH dehydrogenase via a mechanism in which NAD+ and PQQ are involved.

Alcohol Oxidoreductases↗