Understanding the Small Molecule Recognition by Carbonyl Reductase

Anthracyclines are commonly used drugs to treat a variety of cancers. While they are effective drugs, they also have potential cardiotoxic effects upon reduction. Human Carbonyl Reductase (HCBR) is a natural enzyme which converts anthracyclines into their alcoholic metabolites and renders them ineffective. Our lab has been studying the activity of the wild type (WT) form of HCBR along with other forms in which amino acids in the active site have been changed via site-directed mutagenesis. To prevent HCBR from reducing carbonyl compounds into their alcoholic metabolites a candidate inhibitor, resveratrol was introduced. Our lab used various techniques to understand the activity of the WT with resveratrol by an IC50 and inhibition study. Resveratrol was found to inhibit the WT uncompetitively with an IC50 and Kii value of 2.8(0.6) µM and 3(0.5) µM, respectively, using a prototype carbonyl substrate, menadione. We did a KM study with the mutant forms M141A and M141S and found them to be much higher than the WT with values of 120(3)µM and 210(95)µM, respectively. It was determined that both are not inhibited by resveratrol. (NIH Grant # P20 RR016454)