Evidence for the involvement and role of a corrinoid enzyme in methane formation from acetate in Methanosarcina barkeri

Methane formation from acetate in cell suspensions of Methanosarcina barkeri was inhibited by low concentrations (5 M) of propyl iodide. Inhibition was abolished by short exposure of the suspension to light which strongly indicates that a corrinoid enzyme is involved in methanogenesis from acetate. Propyl iodide (5M) had no effect on the exchange reaction between the carboxyl group of acetate and ¹⁴CO₂, and on methane formation from methanol, from H₂ and methanol, or from H₂ and CO₂. These findings indicate that the proposed corrinoid enzyme has a role in methyl group transfer to coenzyme M after C-C cleavage of acetate.Dedicated to Professor N. Pfennig on the occasion of his 60th birthday