title: Biosynthesis of vitamin B12: mode of incorporation of factor III into cobyrinic acid.
abstract: Extensive chemical degradation of cobyrinic acid biosynthesized from a sample of factor III radiochemically labeled in its three methyl groups demonstrates that label is retained exclusively in the two methyl groups at positions C-2 and C-7 and confirms that the C-20 methyl group of the precursor is lost during formation of the corrin ring system.
mesh_terms: D001429:Bacteriochlorophylls / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D011424:Propionibacterium / Q000378:metabolism; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000096:biosynthesis*
chemical_list: D001429:Bacteriochlorophylls; C010895:cobyrinic acid; D014805:Vitamin B 12