bacteriochlorophylls and cobamamide

bacteriochlorophylls has been researched along with cobamamide* in 1 studies

Other Studies

1 other study(ies) available for bacteriochlorophylls and cobamamide

ArticleYear
Anaerobic chlorophyll isocyclic ring formation in Rhodobacter capsulatus requires a cobalamin cofactor.
    Proceedings of the National Academy of Sciences of the United States of America, 2000, Jun-06, Volume: 97, Issue:12

    The isocyclic ring of bacteriochlorophyll (BChl) is formed by the conversion of Mg-protoporphyrin monomethyl ester (MPE) to protochlorophyllide (PChlide). Similarities revealed by blast searches with the putative anaerobic MPE-cyclase BchE suggested to us that this protein also uses a cobalamin cofactor. We found that vitamin B(12) (B(12))-requiring mutants of the bluE and bluB genes of Rhodobacter capsulatus, grown without B(12), accumulated Mg-porphyrins. Laser desorption/ionization time-of-flight (LDI-TOF) MS and NMR spectroscopy identified them as MPE and its 3-vinyl-8-ethyl (mvMPE) derivative. An in vivo assay was devised for the cyclase converting MPE to PChlide. Cyclase activity in the B(12)-dependent mutants required B(12) but not protein synthesis. The following reaction mechanism is proposed for this MPE-cyclase reaction. Adenosylcobalamin forms the adenosyl radical, which leads to withdrawal of a hydrogen atom and formation of the benzylic-type 13(1)-radical of MPE. Withdrawal of an electron gives the 13(1)-cation of MPE. Hydroxyl ion attack on the cation gives 13(1)-hydroxy-MPE. Withdrawal of three hydrogen atoms leads successively to 13(1)-keto-MPE, its 13(2)-radical, and cyclization to PChlide.

    Topics: Amino Acid Sequence; Anaerobiosis; Bacteriochlorophylls; Chromatography, Thin Layer; Cobamides; Iron; Molecular Sequence Data; Mutation; Oxygenases; Porphyrins; Rhodobacter capsulatus; Vitamin B 12

2000