Properties of glucose 6-phosphate and 6-phosphogluconate dehydrogenases of the obligate methylotroph Methylobacillus flagellatum KT

Summary

Extracts from the obligate methylotroph Methylobacillus flagellatum KT and its temperature-sensitive (ts) glucose 6-phosphate dehydrogenase (GPD) mutants were analysed by electrophoresis, isoelectrofocusing and chromatography methods. GPD is present in two forms differing in the isoelectric point (IEP) values, but identical in other properties. Both forms are specific to NAD and NADP, have similar affinity to substrates, exhibit equal levels of inhibition by NAD(P)H and ATP and have the same dependence of activity on temperature. The synthesis of both forms is controlled by one gene. 6-phosphogluconate dehydrogenase (GND) is represented by two proteins with different IEP values. One is specific both to NAD and NADP, is stable and inhibited by NADH and NADPH to a similar extent. The second is specific to NAD only, unstable and inhibited by NADH to a greater extent than by NADPH.

Methylobacillus flagellatum, Obligate methylotroph, Glucose 6-phosphate dehydrogenase, 6-Phosphogluconate dehydrogenase