Role of Cys-298 in specific recognition of glutathione by aldose reductase

Aldose reductase (AR) is an NADPH-dependent oxidoreductase that is well-studied for its role in Diabetes Mellitus. Glutathione conjugated aldehydes are efficiently catalysed by AR. We have employed molecular dynamics simulations to investigate the dynamics of a glutathione analog, gamma-glutamyl-S-(1,2-di-carboxyethyl)-cysteinyl-glycine (DCEG), into the binding pocket of AR. Study revealed that backbone nitrogens of Ala-299 and Leu-300 form a tiny pocket gated by thiol group of Cys-298. The glycine moiety of DCEG was able to displace the thiol group of Cys-298 to make hydrogen bond interactions with backbone of Ala-299, Leu-300, and Leu-301. This study provides the details of the dynamic interactions of DCEG in the binding pocket of AR, and shall aid in the design/discovery of differential inhibitors against AR. Communicated by Ramaswamy H. Sarma