Imidazolyl carboxylic acids as mechanistic probes of flavocytochrome P-450 BM3

MA Noble, L Quaroni, GD Chumanov, KL Turner, SK Chapman, RP Hanzlik, AW Munro

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    Abstract

    omega-Imidazolyl carboxylic acids (C10-C12) have been used as probes of the active site and catalytic mechanism of the fatty acid hydroxylase P-450 BM3 from Bacillus megaterium. These compounds are the most potent inhibitors of P-450 BM3 yet reported. All are mixed inhibitors, increasing the K-m and decreasing the k(cat) for laurate oxidation. All ligate the P-450 BM3 ferric heme iron, inducing a type II shift in the Soret absorbance band from 419 to 424 nm. Binding to the ferrous form is much weaker. 10-(Imidazolyl)decanoic acid was the best inhibitor (K-ic = 0.9 mu M, K-iu = 5.7 mu M), while 12-(imidazolyl)dodecanoic acid (K-ic = 1.35 mu M, K-iu = 6.9 mu M) was superior to 11-(imidazolyl)undecanoic acid (K-ic = 7.5 mu M, K-iu = 16 mu M). Dissociation constants for binding to oxidized P-450 BM3 heme iron were determined spectrophotometrically as 8 mu M (C12 azole) and 27 mu M (C11 azole). The binding of 10-(imidazolyl)decanoic acid was too tight for an absolute K-d to be determined spectrophotometrically, but this value is

    Original languageEnglish
    Pages (from-to)15799-15807
    Number of pages9
    JournalBiochemistry
    Volume37
    Issue number45
    DOIs
    Publication statusPublished - 10 Nov 1998

    Keywords

    • INHIBITOR
    • ELECTRON-TRANSFER
    • P450BM-3
    • REDUCTASE
    • SUBSTRATE-BINDING
    • DOMAIN
    • BACILLUS-MEGATERIUM
    • CRYSTAL-STRUCTURE
    • CYTOCHROME-P-450 BM3
    • OMEGA-HYDROXYLATION

    Cite this

    Noble, MA., Quaroni, L., Chumanov, GD., Turner, KL., Chapman, SK., Hanzlik, RP., & Munro, AW. (1998). Imidazolyl carboxylic acids as mechanistic probes of flavocytochrome P-450 BM3. Biochemistry, 37(45), 15799-15807. https://doi.org/10.1021/bi980462d