Abstract
Site-directed mutants were constructed in cytochrome P-450cam to re-engineer the stereochemistry and coupling of ethylbenzene hydroxyiation. The reaction with wild-type (WT) enzyme produces one regioisomer 1-phenylethanol with 5% reduced nicotinamide adenine deoxyribonucleic acid to product conversion of and a ratio of 73:27 for the R and S enantiomers respectively. Ethyibenzene was modeled into the active site of WT P-450cam in a rigid mode and oriented to optimize either pro-R or pro-S hydrogen abstraction. Residues T101, T185 and V247 make extensive contacts with the substrate in the static complexes and were therefore chosen for site-directed mutagenesis. Single mutants T101M, V247A and V247M are more stereospedik producing 89,87 and 82% (R)-1-phenylethanol respectively. The coupling of the reaction is doubled for the single mutants T185L, T185F and V247M. In an effort to engineer increased stereospecificity and coupling into a single catalyst the T101M, T185F and V247M mutants were combined in a multiple mutant of P-450cam.This protein hydroxylates ethyibenzene resulting in an R:S ratio of 87:13 for the 1-phenylethanols and 13% coupling of reducing equivalents to product. The catalytic stereospecificity and stoichiometry with T101M-T185F-V247M does not represent a summation of the changes observed for the single mutants. A portion of the individual effects on substrate recognition produced by the single substitutions is either eliminated or degenerate within the triple mutant.
Original language | English (US) |
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Pages (from-to) | 207-212 |
Number of pages | 6 |
Journal | Protein Engineering, Design and Selection |
Volume | 6 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1993 |
Keywords
- Coupling
- Cytochrome P450cam
- Site-directed mutagenesis
- Stereospecificity
ASJC Scopus subject areas
- Biotechnology
- Bioengineering
- Biochemistry
- Molecular Biology