S-Formyl glutathione as a substrate of bacterial formate dehydrogenase

NAD(+)-dependent formate dehydrogenase

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Dye-linked dehydrogenase activities for formate and formate esters in Amycolatopsis methanolica. Characterization of a molybdoprotein enzyme active with formate esters and aldehydes

Cell-free extracts of methanol-grown Amycolatopsis methanolica contain dye-linked dehydrogenase activities for formate and methyl formate. Fractionation of the extracts revealed that the (unstable) activity for formate resides in membrane particles, while that for methyl formate belongs to a soluble enzyme that was purified and characterized. The enzyme, indicated as formate-ester dehydrogenase, appeared to be a molybdoprotein (4 Fe, 3 or 4 S, 1 Mo and 1 FAD were found for each enzyme molecule), with a molecular mass of 186 kDa and consisting of two subunits of equal size. Product identification suggests that the formate moiety in the ester becomes hydroxylated to a carbonate group after which the unstable alkyl carbonate decomposes into CO2 and the alcohol moiety. Based on structural and catalytic characteristics, the enzyme appears to be very similar to an enzyme isolated from Comamonas testosteroni [Poels, P. A., Groen, B. W. & Duine, J. A. (1987) Eur. J. Biochem. 166, 575-579] which was at that time considered to be an aldehyde dehydrogenase. Formate-ester dehydrogenase activity appeared to be present in several other bacteria. Possible roles for the A. methanolica enzyme in C1 dissimilation (oxidation of methyl formate to methanol and CO2 or a factor-formate adduct to factor plus CO2) or in general aldehyde oxidation, are discussed.

Purification and properties of formate dehydrogenase from Moraxella sp. strain C-1

NAD+-dependent formate dehydrogenase was screened in various bacterial strains. Facultative methanol-utilizing bacteria isolated from soil samples, acclimated to a medium containing methanol and formate at pH 9.5, were classified as members of the genus Moraxella. From a crude extract of Moraxella sp. strain C-1, formate dehydrogenase was purified to homogeneity, as judged by disc gel electrophoresis. The enzyme has an isoelectric point of 3.9 and a molecular weight of approximately 98,000. The enzyme is composed of two identical subunits with molecular weights of about 48,000. The apparent Km values for sodium formate and NAD+ were calculated to be 13 mM and 0.068 mM, respectively.

Biosynthesis, isolation and properties of NAD-dependent formate dehydrogenase from the yeast Candida methylica

NAD-dependent formate dehydrogenase (EC 1.2.1.2), was isolated from the methanol-utilizing yeast Candida methylica. Two purification techniques for the enzyme from the crude yeast extract have been developed: a two-step procedure, involving a sequential application of DEAE-cellulose ion-exchange chromatography and Sephadex G-200 gel filtration, and a single-step procedure, preparative isoelectric focusing in a granulated gel layer. The enzyme proved to be electrophoretically homogeneous. It consisted of two identical subunits with a relative molecular mass of 46 000, each containing one -SH group related to manifestation of the catalytic activity. The Michaelis constant was 1 X 10(-4) M for NAD and 1.3 X 10(-2) M for formate. Formate dehydrogenase was inhibited with p-chlormercuribenzoate, iodoacetamide, dithionitrobenzoate, cyanide and azide.

Molecular cloning of murine interferon gamma (MuIFN-gamma) cDNA and its expression in heterologous mammalian cells

A complete cDNA clone of murine interferon-gamma (MuIFN-gamma) was obtained by recombining two appropriate segments from partial cDNA clones originally identified by colony hybridization with rat IFN-gamma chromosomal gene fragments as probes. An expression vector was constructed in which the cDNA was placed under control of the SV40 early promoter. Transient expression of MuIFN-gamma was obtained by transformation of COS-1 cells. Subsequently, this interferon expression unit was linked to a vector containing a dihydrofolate reductase (DHFR) modular gene and used to transform DHFR(-)-CHO cells. Cell clones were selected that constitutively produce an interferon activity which by several criteria was found to be indistinguishable from natural, splenocyte-derived MuIFN-gamma.