title: Biosynthesis of vitamin B12: identity of fragment extruded during ring contraction to the corrin macrocycle.
abstract: Incorporation experiments with labeled sirohydrochlorin and trimethylisobacteriochlorin demonstrate that ring contraction in vivo to the corrin macrocycle of vitamin B12 liberates acetic acid. The C-20 atom of the precursors becomes the acetate carboxyl carbon.
mesh_terms: D000085:Acetates / Q000096:biosynthesis; D001429:Bacteriochlorophylls / Q000378:metabolism; D002474:Cell-Free System; D055598:Chemical Phenomena; D002621:Chemistry; D045728:Corrinoids; D011424:Propionibacterium / Q000378:metabolism; D014805:Vitamin B 12 / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D000085:Acetates; D001429:Bacteriochlorophylls; D045728:Corrinoids; D014805:Vitamin B 12