Investigating the Role of Methionine 234 in Catalysis by Human Carbonyl Reductase I
Faculty Mentor Information
Henry A. Charlier, Jr.
Abstract
Anthracyclines are a class of effective chemotherapy drugs. A major limitation to the use of anthracyclines is the risk of a chronic cardiotoxicity that is associated with its use. The cardiotoxicity is linked to the NADPH-dependent reduction of anthracyclines by Human Carbonyl Reductase 1 (HCBR1). The creation of an anthracycline that is not reduced by HCBR1 has the potential to lower the risk of anthracycline-associated cardiotoxicity. A study of the active site structure of HCBR1 has identified several key amino acids that may play a role in regulating substrate binding. Molecular modeling with doxorubicin and daunorubicin suggests that Met234 may play a significant role in directing the substrate specificity favoring daunorubicin over doxorubicin. To test this hypothesis, Met234 was replaced with alanine and the steady state kinetics and coenzyme binding with Met234Ala was analyzed. The catalytic efficiencies with several carbonyl substrates was significantly lower for Met234Ala that for the native enzyme. The coenzyme binding affinities were also lowered for the Met234Ala enzyme as well. Though the specific role for Met234 is still under investigation, the results suggest that Met234 is an important amino acid for the proper functioning of HCBR1.
Investigating the Role of Methionine 234 in Catalysis by Human Carbonyl Reductase I
Anthracyclines are a class of effective chemotherapy drugs. A major limitation to the use of anthracyclines is the risk of a chronic cardiotoxicity that is associated with its use. The cardiotoxicity is linked to the NADPH-dependent reduction of anthracyclines by Human Carbonyl Reductase 1 (HCBR1). The creation of an anthracycline that is not reduced by HCBR1 has the potential to lower the risk of anthracycline-associated cardiotoxicity. A study of the active site structure of HCBR1 has identified several key amino acids that may play a role in regulating substrate binding. Molecular modeling with doxorubicin and daunorubicin suggests that Met234 may play a significant role in directing the substrate specificity favoring daunorubicin over doxorubicin. To test this hypothesis, Met234 was replaced with alanine and the steady state kinetics and coenzyme binding with Met234Ala was analyzed. The catalytic efficiencies with several carbonyl substrates was significantly lower for Met234Ala that for the native enzyme. The coenzyme binding affinities were also lowered for the Met234Ala enzyme as well. Though the specific role for Met234 is still under investigation, the results suggest that Met234 is an important amino acid for the proper functioning of HCBR1.