Kinetic Characterization of Chiral Biocatalysis of Cycloarenes by the Camphor 5-Monooxygenase Enzyme System

Published

June 15, 1999

Author(s)

D A. Grayson, V L. Vilker

Abstract

Redox enzyme mediated biocatalysis has the potential to regio - and stereo-specificity oxidive hydrocarbons producing valuable products with minimal by-product formation. In-vitro reactions of the Camphor (cytochrome P-450) 5-monooxygenase enzyme system with naphthalene-like substrates yield stereospecifically hydroxylated products from nonactivated hydrocarbons. Specifically, the enzyme system catalyzes the essentially stereospecific conversion of the cycloarene, tetralin (1,2,3,4-tetrahydronaphthalene) to (R)-1-tetralol ((R)-(-)-1,2,3,4-tetrahydro-1-naphthol). It is shown that this reaction obeys Michaelis-Menten kinetics and that the interactions between the enzyme subunits are not affected by the identity of the substrate. This subunit independence extends to the efficiency of NADH usage by the enzyme system -- subunit ratios do not affect efficiency, but substrate identity does. Tetralin is converted at an efficiency of 13 3%, whereas (R)-1-tetralol is converted at 7.8 0.7%. A model of this system based on Michaelis-Menten parameters for one subunit (Pdx: K_M = 10.2 2 M and both substrates (tetralin: K_M = 66 26 M, Ņ_max = 0.11 0.04 s^-1; and (R)-1-tetralol: K_M = 2800 1300 M, Ņ_max = 0.83 0.22 s^-1) is presented and used to predict the consumption and production of all substrates, products, and cofactors.

Citation

Journal of Molecular Catalysis B-Enzymatic

Volume

6

Issue

6

Pub Type

Journals

Keywords

chiral biosynthesis, cytovchrome P450, tetralin

Citation

Grayson, D. and Vilker, V. (1999), Kinetic Characterization of Chiral Biocatalysis of Cycloarenes by the Camphor 5-Monooxygenase Enzyme System, Journal of Molecular Catalysis B-Enzymatic (Accessed October 10, 2024)