J. Biol. Chem., Vol. 256, Issue 19, 9785-9788, Oct, 1981
Deuterium isotope effects on the product partitioning of fluoromethylglyoxal by glyoxalase I. Proof of a proton transfer mechanism
RV Chari and JW Kozarich
Fluoromethylglyoxal in the presence of glutathione has been shown to
undergo a novel glyoxalase I-catalyzed product partitioning to S-
fluorolactoylglutathione and S-pyruvylglutathione with fluoride
elimination. While the partition ratio (fluoride eliminated/total fluoride)
was insensitive to pH 5.5-7.5 and concentrations of substrate and
glyoxalase I, it was species-dependent. When [1- 2H]fluoromethylglyoxal was
reacted with glyoxalase I, an increase in the partition ratio and retention
of deuterium in the product fluorolactate was observed. This result can
only be explained by a selective primary isotope effect on the protonation
of an enediol intermediate relative to fluoride elimination.
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