title: Modeling the catalytic site of vanadium bromoperoxidase: synthesis and structural characterization of intramolecularly H-bonded vanadium(V) oxoperoxo complexes, [VO(O(2))((NH)2pyg(2))]K and [VO(O(2))((BrNH)2pyg(2))]K.
abstract: Vanadium haloperoxidases (VHPO) catalyze the peroxidative halogenation of organic substrates. Crystallographic studies suggest that hydrogen bonding from a lysine side chain to the vanadium(V)-bound peroxo group may facilitate oxidation of halides (Cl(-), Br(-), I(-)). A ligand with pendant NH(2) functionality, N-(2-pyridylmethyl-6-amino) iminodiacetic acid (H(2)(NH)2pyg(2).2HCl) has been designed to explore the effects that H-bonding from Lys may have on peroxide activation. The first structural characterization of VBrPO model complexes [VO(O(2))((NH)2pyg(2))]K and [VO(O(2))((BrNH)2pyg(2))]K which demonstrate direct intramolecular H-bonding between an amine functionality and V(V)-bound peroxide is reported. The distances between NH(2) proton and bound peroxo moiety [(d(N(1)-H.O): 2.637(4) A in [VO(O(2))((NH)()2pyg(2))]K, and 2.640(8) and 2.6919(8) A in [VO(O(2))((BrNH)2pyg(2))]K] are indicative of intramolecular H-bonding. The intramolecular H-bond strength in [VO(O(2))((BrNH)2pyg(2))](-) is estimated at 6 kcal/mol by (1)H NMR studies and demonstrates that the H-bond interaction is also significant in solution.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, USA.
authors.forename: Clare
authors.initials: C
authors.lastname: Kimblin
authors.forename: Xianhui
authors.initials: X
authors.lastname: Bu
authors.forename: Alison
authors.initials: A
authors.lastname: Butler
mesh_terms: D000588:Amines / Q000737:chemistry; D002384:Catalysis; D020134:Catalytic Domain; D002711:Chloride Peroxidase / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008239:Lysine / Q000737:chemistry; D003904:Mitosporic Fungi / Q000201:enzymology*; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010544:Peroxidases / Q000737:chemistry* / Q000378:metabolism; D010545:Peroxides / Q000138:chemical synthesis / Q000737:chemistry*; D000459:Phaeophyceae / Q000201:enzymology*; D012624:Seaweed / Q000201:enzymology*; D017968:Vanadium Compounds / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D000588:Amines; D010545:Peroxides; D017968:Vanadium Compounds; D010544:Peroxidases; C026195:bromide peroxidase; D002711:Chloride Peroxidase; D008239:Lysine