Reactive cysteines of the 90-kDa heat shock protein, Hsp90

Arch Biochem Biophys. 2000 Dec 1;384(1):59-67. doi: 10.1006/abbi.2000.2075.


The 90-kDa heat shock protein (Hsp90) is the most abundant molecular chaperone of the eukaryotic cytoplasm. Its cysteine groups participate in the interactions of Hsp90 with the heme-regulated eIF-2alpha kinase and molybdate, a stabilizer of Hsp90-protein complexes. In our present studies we investigated the reactivity of the sulfhydryl groups of Hsp90. Our data indicate that Hsp90 as well as two Hsp90 peptides containing Cys-521 and Cys-589/590 are able to reduce cytochrome c. The effect of Hsp90 can be blocked by sulfhydryl reagents including arsenite and cadmium, which indicates the involvement of the vicinal cysteines Cys589/590 in the reduction of cytochrome c. Hsp90 neither reduces the disulfide bonds of insulin nor possesses a NADPH:quinone oxidoreductase activity. Oxidizing conditions impair the chaperone activity of Hsp90 toward citrate synthase. The high and specific reactivity of Hsp90 cysteine groups toward cytochrome c may indicate a role of this chaperone in modulation of the redox status of the cytosol in resting and apoptotic cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cysteine / metabolism*
  • Cytochrome c Group / metabolism
  • HSP90 Heat-Shock Proteins / metabolism*
  • Molecular Chaperones / metabolism
  • Molecular Sequence Data
  • Molecular Weight
  • Oxidation-Reduction
  • Peptide Fragments / metabolism
  • Protein Disulfide Reductase (Glutathione) / metabolism
  • Rats
  • Sequence Homology, Amino Acid
  • Sulfhydryl Reagents / metabolism


  • Cytochrome c Group
  • HSP90 Heat-Shock Proteins
  • Molecular Chaperones
  • Peptide Fragments
  • Sulfhydryl Reagents
  • Protein Disulfide Reductase (Glutathione)
  • Cysteine