PT  - JOURNAL ARTICLE
AU  - Nelson, Sidney D.
AU  - Trager, William F.
TI  - THE USE OF DEUTERIUM ISOTOPE EFFECTS TO PROBE THE ACTIVE SITE PROPERTIES, MECHANISM OF CYTOCHROME P450-CATALYZED REACTIONS, AND MECHANISMS OF METABOLICALLY DEPENDENT TOXICITY
AID  - 10.1124/dmd.31.12.1481
DP  - 2003 Dec 01
TA  - Drug Metabolism and Disposition
PG  - 1481--1497
VI  - 31
IP  - 12
4099  - http://dmd.aspetjournals.org/content/31/12/1481.short
4100  - http://dmd.aspetjournals.org/content/31/12/1481.full
SO  - Drug Metab Dispos2003 Dec 01; 31
AB  - Critical elements from studies that have led to our current understanding of the factors that cause the observed primary deuterium isotope effect, (kH/kD)obs, of most enzymatically mediated reactions to be much smaller than the “true” or intrinsic primary deuterium isotope effect, kH/kD, for the reaction are presented. This new understanding has provided a unique and powerful tool for probing the catalytic and active site properties of enzymes, particularly the cytochromes P450 (P450). Examples are presented that illustrate how the technique has been used to determine kH/kD, and properties such as the catalytic nature of the reactive oxenoid intermediate, prochiral selectivity, the chemical and enzymatic mechanisms of cytochrome P450-catalyzed reactions, and the relative active site size of different P450 isoforms. Examples are also presented of how deuterium isotope effects have been used to probe mechanisms of the formation of reactive metabolites that can cause toxic effects. The American Society for Pharmacology and Experimental Therapeutics