Direct demonstration by 1H n.m.r. spectrometry of the stereoselectivity of yeast glyoxalase I towards the diastereomeric forms of the α-ketoaldehyde–glutathione hemithioacetal

Abstract

Addition of yeast glyoxalase I at pD 4.4 leads to selective disappearance of one of the diastereotopic methine proton signals of the phenylglyoxal–glutathione hemithioacetal, the diastereomer with the lower field signal reacting preferentially with the enzyme, which directly establishes asymmetric binding of the hemithioacetal carbon region as the origin of the stereospecificity of the glyoxalase I reaction to form (S)-D-mandeloylglutathione.