Effect of Deuteration on the Activity of Methanol Dehydrogenase from Methylophilus sp. B-7741

We studied the effect of deuterium oxide present in the medium on the activity of methanol dehydrogenase (EC 1.1.99.8) from methylotrophic bacteria Methylophilus sp. B-7741. Methanol dehydrogenase activity in extracts of the biomass obtained in a highly deuterated medium (2H-enzyme) was 34–47% of the enzyme activity in the control biomass (1H-enzyme), which depended on the reaction conditions. The isotopic effects of substrate deuterium (methanol) for 1H-enzyme and 2H-enzyme were 1.37 ± 0.05 and 1.38 ± 0.01, respectively. We revealed for the first time the reverse isotopic effect of solvent deuterium in the reaction catalyzed by methanol dehydrogenase (0.80 ± 0.02 and 0.60 ± 0.01 for 1H-enzyme and 2H-enzyme, respectively).