The active-site residue tyr-175 in human glyoxalase II contributes to binding of glutathione derivatives.

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Ridderstrom M, Jemth P, Cameron AD, Mannervik B

The active-site residue tyr-175 in human glyoxalase II contributes to binding of glutathione derivatives.

Biochim Biophys Acta. 2000 Sep 29;1481(2):344-8.

PubMed ID

11018726 [ View in PubMed

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Abstract

Tyrosine-175 located in the active site of human glyoxalase II was replaced by phenylalanine in order to study the contribution of this residue to catalysis. The mutation had a marginal effect on the k(cat) value determined using S-D-lactoylglutathione as substrate. However, the Y175F mutant had an 8-fold higher K(m) value than the wild-type enzyme. The competitive inhibitor S-(N-hydroxy-N-bromophenylcarbamoyl)glutathione had a 30-fold higher K(i) value towards the mutant, than that of the wild-type. Pre-equilibrium fluorescence studies with the inhibitor showed that this was due to a significantly increased off-rate for the mutant enzyme. The phenolic hydroxyl group of tyrosine-175 is within hydrogen bonding distance of the amide nitrogen of the glycine in the glutathione moiety and the present study shows that this interaction makes a significant contribution to the binding of the active-site ligand.

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Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Glutathione	Hydroxyacylglutathione hydrolase, mitochondrial	Protein	Humans	Unknown	Not Available	Details