COMPUTATIONAL STUDY OF ALKENE REDUCTION IN OLD YELLOW ENZYMES

M. Pilar Buteler† , Sunidhi Lenka† , Robert W. Powell, III, Jon D. Stewart and Adrian E. Roitberg

Department of Chemistry, 126 Sisler Hall, University of Florida, Gainesville, FL 32611 USA

Old Yellow Enzymes are isolated from brewer’s bottom yeast (Saccharomyces cerevisiae ). They are known for reduction of electron deficient alkenes with very high stereoselectivity. OYE 1, OYE 2 and OYE 3, are homologs of old yellow enzymes with high sequence identity. OYE 3 is 80 % identical in sequence to OYE 1, but experiments show that they produce different stereoselective products profiles for some alkene substrates. Within the active site of both enzymes the only difference found was at position 296, with Phe for OYE 1 and Ser for OYE 3. We performed molecular dynamics to rationalize the difference in stereoselectivities. The dynamic properties of loop 6(289-309) were significantly different for both the enzymes indicating the loop playing a major role in difference in stereoselectivities. Furthermore, experimentally it was found that site saturation mutagenesis of Trp 116 resulted in major differences in stereoselectivity for substrate (S)- carvone and (R)- carvone in case of OYE 1 and had little impact in OYE 3. To summarize molecular dynamics studies are being conducted to provide a deeper perspective of the enzyme properties.