The role of the conserved threonine in P450BM3 oxygen activation: Substrate-determined hydroxylation activity of the Thr268Ala mutant

Max J. Cryle, James J. De Voss

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22 Citations (Scopus)


The hydroxylation activity of the Thr268Ala mutant of P450BM3 has been shown to occur to varying degrees with small alterations in the structure of a fatty-acid substrate. Ten substrates were investigated, including straight chain, branched chain and cis-cyclopropyl substituted fatty acids with a straight-chain length that varied between 12 and 16 carbon atoms. The efficacy of the hydroxylation activity appeared to be governed by the chain length of the substrate. Substrates possessing 14 to 15 carbons afforded the highest levels of activity, which were comparable with the wild-type enzyme. Outside of this window, straight-chain fatty acids showed reduced activity over the other substrate types. These results provide a cautionary tale concerning the loss of ferryl activity in such cytochrome P450 threonine to alanine mutants, as the nature of the substrate can determine the extent to which hydroxylation chemistry is abolished.

Original languageEnglish
Pages (from-to)261-266
Number of pages6
Issue number2
Publication statusPublished - 25 Jan 2008


  • CYP102A1
  • Cytochromes P450
  • Enzyme catalysis
  • Fatty acids
  • P450

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