Biosynthesis of porphyrins and related macrocycles, part 43. Isolation and characterization of intermediates of coenzyme B12 biosynthesis, a cobyrinic acid triamide, the a,c-diamide and their Co-(5′-deoxy-5′-adenosyl) derivatives, from Propionibacterium s

Background: Vitamin B12 is synthesized by many different organisms, for example Pseudomonas denitrificans (aerobic) and Propionibacterium shermanii (‘microaerophilic’, or essentially anaerobic). The biosynthetic pathways in these two organisms show strong similarities but also some differences. There have been conflicting reports on where differences between these two organisms lie in the stages beyond the formation of the corrin macrocycle. Characterization of intermediates in the pathway will help resolve these conflicts.