Methanol dehydrogenase

Carboxylic acids with labile a-methylene protons react with isatin in the presence of strong aqueous base. In the total synthesis of methoxatin, the coenzyme of methanol dehydrogenase and glucose dehydrogenase, Weinreb employs a Pfitzinger condensation of an isatin 37 and pyruvic acid as a key step to provide the 4-quinolinic acid 38 in 50% yield under the standard basic conditions. ... 

Kuwabata S, Nishida K, Tsuda R, Inoue H, Yoneyama H (1994) Photochemical reduction of carbon dioxide to methanol using ZnS microcrystaUite as a photocatalyst in the presence of methanol dehydrogenase. J Electrochem Soc 141 1498-1503... 

Conversion of methanol into formaldehyde by methanol dehydrogenase. A complex array of genes is involved in this oxidation and the dehydrogenase contains pyrroloquinoline quinone (PQQ) as a cofactor (references in Ramamoorthi and Lidstrom 1995). Details of its function must, however, differ from that of methylamine dehydrogenase that also contains a quinoprotein—tryptophan tryptophylquinone (TTQ). 

M. Ghosh, C. Anthony, K. Harlos, M.G. Goodwin, and C. Blake, The refined structure of the quino-protein methanol dehydrogenase from Methylobacterium extorquens at 1.94A. Structure 3, 177—187 (1995). 

C. Anthony, M. Ghosh, and C.C. Blake, The structure and function of methanol dehydrogenase and related quinoproteins containing pyrrolo-quinoline quinone. Biochem. J. 304, 665-674 (1994). 

NAD(P)+ as Anode Mediator. A majority of redox enzymes require the cation nicotinamide adenine dinucleotide, possibly phosphorylated (NAD(P)+) as a cofactor. Of the oxidoreductases listed in Enzyme Nomenclature, over 60% have NAD(P)+ as a reactant or product.For example, methanol can be oxidized to form formaldehyde by methanol dehydrogenase (MDH, EC 1.1.1.244) according to... 

Pyrroloquinoline quinone (PQQ) (or methoxatin) 6 is a coenzyme, responsible for the oxidation of methanol [7]. It has been found that cyclopropanol 4 inactivates the enzyme from M. methanica [8], the dimeric methanol dehydrogenase and the monomeric enzyme from a Pseudomonas PQQ-dependent methanol dehydrogenase [9] by forming adducts such as 7, through a one-electron oxidation process and the ready ring opening of a cyclopropyloxonium radical, Eq. (3) [8,9]. 

This enzyme [EC 1.1.99.8], also referred to as alcohol dehydrogenase (acceptor) and methanol dehydrogenase, catalyzes the oxidation-reduction reaction of a primary alcohol with an acceptor to generate an aldehyde and the reduced acceptor. The cofactor for this enzyme is pyrroloquinoline qutnone (PQQ). A wide variety of primary alcohols can act as the substrate. See also Alcohol Dehydrogenase... 

OXYGEN, OXIDES 0X0 ANIONS METHANE MONOOXYGENASE Methanol, autoprotolysis constant, AUTOPROTOLYSIS METHANOL DEHYDROGENASE... 

Methanol dehydrogenase, 45 359, 360, 364 Methemerythrin, 33 216 Melhionine, H NMR, 36 10-11 m-Methoxybenzoic acid, metal carbonyl derivatives, 8 51... 

More complex reductions of CO2 by enzyme cascades have also been achieved. A combination of an electron mediator and two enzymes, formate dehydrogenase and methanol dehydrogenase, was used to reduce CO2 to methanol. This system operates with current efficiencies as high as 90% and low overpotentials (approximately —0.8 V vs. SCE at pH 7) [125]. The high selectivity and energy efficiency of this system indicate the potential of enzyme cascades. There are also drawbacks to these systems. In general, enzymes are... 

Evidence for a hydride transfer mechanism (Scheme 29) for the PQQ-dependent enzyme methanol dehydrogenase (MDH) was obtained by a theoretical analysis combined with an improved refinement of a 1.9 A resolution crystal structure of MDH from Methylophilus methylotrophus in the presence of CH3OH <2001PNA432>. The alternative mechanism proceeding via a hemiketal intermediate was discounted when the observed tetrahedral configuration of the C-5 atom of PQQ in that crystal structure was shown to be the C-5-reduced form of the cofactor 198, a precursor to the more common reduced form of PQQ 199. 

Harms, N. Reijnders, W.N. Anazawa, H. van der Palen, C.J. van Spanning, R.J. Oltmann, L.E Stouthamer, A.H. Identification of a two-compo-nent regulatory system controlling methanol dehydrogenase synthesis in Paracoccus denitrificans. Mol. Microbiol., 8, 457-470 (1993)... 

Bacteria that oxidize methane or methanol (methylotrophs) employ a periplasmic methanol dehydrogenase that contains as a bound coenzyme, the pyrroloquinoline quinone designated PQQ or meth-oxatin (Eq. 15-51).442 I 1 1 This fluorescent ortfzo-quinone... 

Figure 15-23 (A) Stereoscopic view of the H subunit of methanol dehydrogenase. Eight four-stranded antiparallel 3 sheets, labeled W1-W8, form the base of the subunit. Several helices and two additional P-sheet structures (labeled Px and Py) form a cap over the base. The PQQ is located in a funnel within the cap approximately on an eight-fold axis of pseudosymmetry. Courtesy of Xia et al.ii7 (B) Schematic view of the active site. W467 is parallel to the plane of PQQ. All hydrogen-bond interactions between PQQ and its surrounding atoms, except for the three water molecules, are indicated. Courtesy of White et al.ii8...

When FI is replaced by PQQ (pyrroloquinolinequinone), a novel heterocyclic o-quinone cofactor that was first isolated and identified from methanol dehydrogenase of methylotrophic bacteria in 1979 [68], the photochemical oxidation of benzyl alcohols occurs efficiently without HC104 in MeCN [69] ... 

ZnS colloids were also used by Kuwabata et al. to photoreduce C02 to formate [130]. In this system, the ZnS colloids also reduced pyrroloquinoline quinone which served as an electron mediator to the enzyme, methanol dehydrogenase, which could then reduce formate to methanol. In C02-saturated aqueous solution at pH 7 and under far-UV (280nm) illumination, quantum efficiencies of 7% and 6% were achieved for formate and methanol, respectively. 

Cozier, G. E., and Anthony, C. (1995a). Structure of the quinoprotein glucose dehydrogenase of Escherichia coli modelled on that of methanol dehydrogenase from Methylobact-erium extorquens. Biochem. J., 312, 679-685. 

Ghosh, M., Anthony, C., Harlos, K., Goodwin, M. G., and Blake, C. (1995). The refined structure of the quinoprotein methanol dehydrogenase from Methylobacterium ex-torquens at 1.94 A. Structure, 3, 177-187. 

Different 2H-, 13C- and/or 15N isotopomers of L-serine, [(S)-2-amino-3-hydroxypro-panoic acid], 95, required for studies of aminoacid metabolism and for studies of peptide and protein structure and dynamics, have been biosynthesized stereoselectively84 using the serine-type methylotrophic bacterium, Methylobacteri extorquens AMI, which contains85 large amounts of the enzymes methanol dehydrogenase and hydroxymethyl-transferase (equation 39). 

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