Identification of the reactive cysteine residue in human placenta aldose reductase

Si Qi Liu, Aruni Bhatnagar, Naseem H. Ansari, Satish K. Srivastava

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)268-272
Number of pages5
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Issue number3
StatePublished - Aug 7 1993
Externally publishedYes


  • Aldose reductase
  • Enzyme modification
  • Reactive residue

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Molecular Biology


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