Abstract Title

A Role for Methionine 234 in the Substrate Specificity of Human Carbonyl Reductase

Disciplines

Chemicals and Drugs | Enzymes and Coenzymes | Medicine and Health Sciences

Abstract

Doxorubicin, daunorubicin and many other anthracyclines make up some of the most popular chemotherapy drugs used today. Once absorbed into the body, the naturally occurring enzyme Human Carbonyl Reductase 1 (HCBR1) has been shown to catalyze the NADPH-dependent reduction of these anthracyclines. This reaction produces alcohol metabolites that contain dangerous cardiotoxic properties. Discovering a way to advance anthracyclines so they no longer represent substrates for HCBR1 can possibly eliminate the amount of cardiotoxic side effects produced by the drugs. The focus of this study is to determine the possible role of methionine 234 in binding and substrate specificity of HCBR1 and to gain more of an understanding as to how HCBR1 binds small molecules within its active site. Steady-state kinetics were performed with a mutant HCBR1 where MET234 was replaced with an alanine. The catalytic efficiency with menadione (carbonyl substrate) was decreased by 0.041 as compared to the wild-type. This diminished efficiency suggests a role for MET234 in orienting the carbonyl substrate for catalysis.

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A Role for Methionine 234 in the Substrate Specificity of Human Carbonyl Reductase

Doxorubicin, daunorubicin and many other anthracyclines make up some of the most popular chemotherapy drugs used today. Once absorbed into the body, the naturally occurring enzyme Human Carbonyl Reductase 1 (HCBR1) has been shown to catalyze the NADPH-dependent reduction of these anthracyclines. This reaction produces alcohol metabolites that contain dangerous cardiotoxic properties. Discovering a way to advance anthracyclines so they no longer represent substrates for HCBR1 can possibly eliminate the amount of cardiotoxic side effects produced by the drugs. The focus of this study is to determine the possible role of methionine 234 in binding and substrate specificity of HCBR1 and to gain more of an understanding as to how HCBR1 binds small molecules within its active site. Steady-state kinetics were performed with a mutant HCBR1 where MET234 was replaced with an alanine. The catalytic efficiency with menadione (carbonyl substrate) was decreased by 0.041 as compared to the wild-type. This diminished efficiency suggests a role for MET234 in orienting the carbonyl substrate for catalysis.