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1: Biochim Biophys Acta. 1993 Aug 7;1164(3):268-72.Links

Identification of the reactive cysteine residue in human placenta aldose reductase.

Liu SQ, Bhatnagar A, Ansari NH, Srivastava SK.

Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77555.

Modification of human placental aldose reductase by iodoacetate (IAA) led to a mol/mol binding of IAA, a 40% decrease in the kcat, a 3-5-fold increase in the Km,NADPH and Km,glyceraldehyde and a 600-fold increase in the Ki,sorbinil; determined at pH 6.0. NADPH and 2'-monophosphoadenosine 5'-diphosphoribose but neither glyceraldehyde nor sorbinil, prevented carboxymethylation-induced changes. Cleavage of [14C]IAA-modified enzyme by trypsin resulted in two radiolabeled peptides: Val-297 to Lys-307 and Val-297 to Phe-315. In both these peptides Cys-298 was the only radiolabeled residue. It is suggested that Cys-298 regulates the kinetic and inhibition properties of the enzyme, but does not participate in catalysis.

PMID: 8343525 [PubMed - indexed for MEDLINE]