title: Mechanism of the ring contraction process in vitamin B12 biosynthesis by the anaerobe Propionibacterium shermanii under aerobic conditions.
abstract: The mechanism of the ring contraction process during vitamin B(12) biosynthesis by the anaerobe Propionibacterium shermanii was investigated under both aerobic and anaerobic conditions by means of feeding experiments with delta-amino[1-(13)C]levulinic acid (a biosynthetic intermediate of tetrapyrrole) and delta-amino[1-(13)C,1,1,4-(18)O(3)]levulinic acid in combination with (13)C-NMR spectroscopy. We showed that the characteristic mechanism of the ring contraction process (the generation of precorrin-3x from formation of the gamma-lactone from the ring A acetate group at C1 and hydroxylation at C20 by molecular oxygen catalyzed by CobG, and the migration of ring D by cleavage of the carbon-oxygen bond at C1 of precorrin-3x) in the aerobe Pseudomonas denitrificans was not seen in P. shermanii under aerobic conditions, and the mechanism of the ring contraction process in P. shermanii was the same irrespective of the presence or absence of oxygen.
authors.affiliation: Department of Medicinal Chemistry, Meiji Pharmaceutical University, Kiyose-shi, Tokyo, Japan. iida@my-pharm.ac.jp
authors.forename: Katsumi
authors.initials: K
authors.lastname: Iida
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ohtaka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kajiwara
mesh_terms: D000577:Amides / Q000737:chemistry; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D007783:Lactones / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D011424:Propionibacterium / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D014805:Vitamin B 12 / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D000577:Amides; D007783:Lactones; D002244:Carbon; D014805:Vitamin B 12; D010100:Oxygen