Sirohydrochlorin, a precursor of factor F430 biosynthesis in Methanobacterium thermoautotrophicum

Factor F 430 is a nickel-containing coenzyme of methanogenic bacteria with porphinoid structure which is derived from uroporphyrinogen III. It is shown that sirohydrochlorin is metabolized by cell free extracts of Methanobacterium thermoautotrophicum to factor F 430 demonstrating that this compound, or a reduced form of it, is an intermediate in the biosynthesis of F 430, and not only of vitamin B 12 and siroheme.