Methanol dehydrogenase: Mechanism of action

Methanol dehydrogenase (MDH, EC 1.1.99.8) was first described in 1964 by Anthony and Zatman (Anthony and Zatman 1964, 1965, 1967a,b). Since that time a large number of MDH’s have been found with similar properties (Anthony 1986) including the dimeric MDH from Hyphomicrobium X (Duine et al. 1978). Methanol dehydrogenases are dye-linked enzymes, efficient electron transfer occurring exclusively to cationic electron acceptors at relatively high pH values (> 9). Enzymatic activity requires the presence of ammonia and sometimes higher amines as activators. Like many other quinoproteins, MDH’s are characterized by a broad substrate specificity, besides methanol a wide range of primary alcohols is oxidized and some enzymes also oxidize secondary alcohols. Formaldehyde, and sometimes acetaldehyde, is also a substrate. Modulation of the substrate specificity by a modifier protein has been observed in several organisms (Bolbot and Anthony, 1980) and it has been suggested that this protein functions as a regulator of formaldehyde oxidation.