title: New insights into the first oxidative phenol coupling reaction during vancomycin biosynthesis.
abstract: OxyB catalyzes the first oxidative phenol coupling reaction in vancomycin biosynthesis. OxyB is a P450 hemoprotein whose activity is strictly dependent upon the presence of molecular oxygen. Here, it was shown that label from (18)O(2) is not incorporated into the monocyclic product during catalysis by OxyB. In addition, it was shown that OxyB can convert a model hexapeptide substrate containing (R)-Tyr6, instead of (S)-Tyr6, covalently linked as a C-terminal thioester to a peptidyl carrier protein (PCP-7S) derived from the vancomycin non-ribosomal peptide synthetase (NRPS), into the corresponding epimeric monocyclic product. The binding of this epimeric hexapeptide-PCP conjugate to the Fe(III) form of OxyB, as monitored by UV-vis spectroscopy, revealed a K(d)=35+/-5 microM. Thus, the enzyme reveals a surprising lack of stereospecificity in the binding and transformation of these epimeric substrates.
authors: Department of Chemistry, Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors: Nina
authors: N
authors: Geib
authors: Katharina
authors: K
authors: Woithe
authors: Katja
authors: K
authors: Zerbe
authors: Dong Bo
authors: DB
authors: Li
authors: John A
authors: JA
authors: Robinson
mesh_terms: D001667:Binding, Competitive; D002352:Carrier Proteins / Q000737:chemistry; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D010103:Oxygen Isotopes; D010455:Peptides / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism; D014640:Vancomycin / Q000096:biosynthesis / Q000737:chemistry*
chemical_list: D002352:Carrier Proteins; D010103:Oxygen Isotopes; D010455:Peptides; D010636:Phenols; D014640:Vancomycin; D003577:Cytochrome P-450 Enzyme System; D010100:Oxygen