ENZYME CHEMISTRY OF DITHIOHEMIACETALS - SYNTHESIS AND CHARACTERIZATION OF S-D-DITHIOMANDELOYLGLUTATHIONE AS AN ALTERNATE SUBSTRATE FOR GLYOXALASE-I

Both the D- and L-forms of S-dithiomandeloylglutathione (1) have been synthesized by a dithioester-interchange reaction between GSH and S-carboxymethyl(D,L)-dithiomandelate. Kinetic and product analysis studies indicate that yeast glyoxalase I efficiently catalyzes the stereoselective conversion of D-1 to GSH-phenylglyoxal dithiohemiacetal (2), isolated as a disulfide adduct between 2 and a second molecule of GSH. This observation suggests that dithioester substrate analogues should be generally useful as mechanistic probes of enzyme catalyzed reactions involving thiohemiacetal intermediates. © 1991.