TETRALIN AS A SUBSTRATE FOR CAMPHOR (CYTOCHROME-P450) 5-MONOOXYGENASE

Camphor (cytochrome P450) 5-monooxygenase, originally isolated from th e bacterium Pseudomonas putida PgG 786, catalyzes the essentially ster eospecific conversion of tetralin (1,2,3,4-tetrahydronaphthalene) to ( R)-1-tetralol ((R)-(-)-1,2,3,4-tetrahydro-1-naphthol): tetralin(aq) NADH(aq) + O-2(aq) = (R)-1-tetralol(aq) + NAD(aq) + H2O(1). The ratio of the amount of (S)-1-tetralol to the amount of (R)-1-tetralol is sma ll (approximate to 0.04) and the reaction is essentially stereospecifi c. The reaction time-course plot indicates the formation of additional product(s) from the (R)-1-tetralol. It is found that the above reacti on obeys Michaelis-Menten kinetics and that dimethyl sulfoxide, methan ol, and p-dioxane serve as accelerators. Approximate values of a Micha elis constant K-m, limiting rate V-max, and catalytic constant k(cat) are obtained for this reaction under a specified set of conditions. It is shown by means of a thermochemical cycle calculation that the appa rent equilibrium constant for this reaction is approximate to 4 x 10(6 5) at T = 298.15 K and pH 7.3. Thus, this reaction is ''irreversible'' and, unless the enzyme system is inactivated, it will proceed in the direction of complete formation of 1-tetralol from tetralin. A detaile d description of the preparation of the camphor (cytochrome P450) 5-mo nooxygenase enzyme system from recombinant microorganisms is given. (C ) 1996 Academic Press, Inc.