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Hydroxylation Activity (hydroxylation + activity)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

The Role of the Conserved Threonine in P450BM3 Oxygen Activation: Substrate-Determined Hydroxylation Activity of the Thr268Ala Mutant

CHEMBIOCHEM, Issue 2 2008
Max J. Cryle Dr.
Abstract 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. [source]

Functional Characterization of CYP2C8.13 and CYP2C8.14: Catalytic Activities toward Paclitaxel

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2010
Nobumitsu Hanioka
We recently identified two novel CYP2C8 alleles (CYP2C8*13 and CYP2C8*14; wild-type, CYP2C8*1A) with non-synonymous single nucleotide polymorphisms in a Japanese population. To precisely investigate the effect of amino acid substitutions (CYP2C8*13, Ile223Met; CYP2C8*14, Ala238Pro) on CYP2C8 function, CYP2C8 proteins of the wild-type (CYP2C8.1) and variants (CYP2C8.13 and CYP2C8.14) were heterologously expressed in yeast cells, and their paclitaxel 6,-hydroxylation activities were determined. The Km, Vmax and CLint values for paclitaxel 6,-hydroxylation of CYP2C8.1 were 2.3 ,M, 4.1 pmol/min./pmol CYP and 1.7 ,l/min./pmol CYP, respectively. The Km value of CYP2C8.14 was significantly higher (2.9-fold) than that of CYP2C8.1. The Vmax value of CYP2C8.14 was comparable to that of CYP2C8.1 and the CLint value was reduced to 46% of CYP2C8.1. In contrast, the Km, Vmax and CLint values of CYP2C8.13 were similar to those of CYP2C8.1. These results suggest that Ala238Pro substitution in CYP2C8.14 decreases the affinity toward paclitaxel of the CYP2C8 enzyme, and that the genetic polymorphism of the CYP2C8*14 allele may influence the clinical response to drugs metabolized mainly by CYP2C8. [source]

Structural Diversification of Macrolactones by Substrate-Flexible Cytochrome P450 Monooxygenases

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2005
Kil Lee
Abstract The substrate flexibilities of several cytochrome P450 monooxygenases involved in macrolide biosynthesis were investigated to test their potential for the generation of novel macrolides. PikC hydroxylase in the pikromycin producer Streptomyces venezuelae accepted oleandomycin as an alternative substrate and introduced a hydroxy group at the C-4 position, which is different from the intrinsic C-12 hydroxylation position in the natural substrate. This is the first report of C-4 hydroxylation activity of cytochrome P450 monooxygenase involved in the biosynthesis of 14-membered macrolides. EryF hydroxylase from the erythromycin biosynthetic pathway of Saccharopolyspora erythraea and OleP oxidase from the oleandomycin biosynthetic pathway of Streptomyces antibioticus also showed a certain degree of plasticity towards alternative substrates. In particular, EryF and OleP were found to oxidize a 12-membered macrolactone as an alternative substrate. These results demonstrate the potential usefulness of these enzymes to diversify macrolactones by post-PKS oxidations. [source]

The Role of the Conserved Threonine in P450BM3 Oxygen Activation: Substrate-Determined Hydroxylation Activity of the Thr268Ala Mutant

CHEMBIOCHEM, Issue 2 2008
Max J. Cryle Dr.
Abstract 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. [source]