Microbiological and Biochemical Studies Towards Optimization of Substrate Utilization by Methanogenic Bacteria. Annual Report December 1983 - December 1984

摘要

The pathway of acetate conversion to methane and carbon dioxide was studied in Methanosarcina strain TM-1. It was shown that the methyl group of acetate was transferred to coenzyme M which unequivocally demonstrates that methyl coenzyme M is an intermediate in the pathway. The levels of an enzyme system that demethylates methyl coenzyme M and requires carbon monoxide was correlated with growth on acetate which implicates this system in the pathway of acetate to methane. However, free carbon monoxide was shown not to be an intermediate in the pathway which suggests that carbon monoxide may be bound to a site which forms a reduced C1 intermediate from the carboxyl group of acetate. Biotin, Fe, Co and Ni were shown to be required for growth of Methanococcoides methylutens on methylotrophic substrates. Electron paramagnetic resonance (epr) spectroscopy of formate dehydrogenase from Methanobacterium formicicum revealed that cyanide binds to molybdenum in the enzyme which alters the properties of enzyme and renders it inactive. In the presence of cyanide, epr signals from the iron-sulfur and flavin centers are unmasked which allows further study of the epr properties of these centers to elucidate the mechanism of action of the enzyme.