RT Journal Article SR Electronic(1) A1 Page, M. Dudley A1 Anthony, ChristopherYR 1986 T1 Regulation of Formaldehyde Oxidation by the Methanol Dehydrogenase Modifier Proteins of Methylophilus methylotrophus and Pseudomonas AM1 JF Microbiology, VO 132 IS 6 SP 1553 OP 1563 DO https://doi.org/10.1099/00221287-132-6-1553 PB Microbiology Society, SN 1465-2080, AB The modifier protein (M-protein) for methanol dehydrogenase (MDH) of the obligate methylotroph Methylophilus methylotrophus was purified almost to homogeneity (98%pure), characterized and shown to be similar to that previously described in the facultative methylotroph Pseudomonas AM1. It was a dimer of M r 140000, its isoelectric point was 5ยท6 and it showed no spectral absorbance above 320 nm. In the dye-linked MDH assay system, the M-proteins facilitated oxidation of alcohols not normally oxidized (1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol and 3-methylbutanol) by increasing the affinity of MDH for these alcohols. The effect of M-protein on the oxidation of formaldehyde was to decrease the affinity of MDH for formaldehyde by more than 97%, thus preventing any significant oxidation of formaldehyde. The M-protein also exerted its effect on the activity of MDH in the cytochrome-linked system of M. methylotrophus. The usual function of M-protein in methylotrophs is apparently to prevent formaldehyde oxidation. A dye-linked aldehyde dehydrogenase of wide specificity was partially purified and characterized; it failed to oxidize formaldehyde at a significant rate but it oxidized lactaldehyde at a rate sufficient to account for the oxidation of propanediol to lactate in whole bacteria., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-132-6-1553