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

Gábor Nardai, Bálint Sass, Jordan Eber, Gyárgy Orosz, Péter Csermely

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67 Citations (Scopus)


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-2α 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. (C) 2000 Academic Press.

Original languageEnglish
Pages (from-to)59-67
Number of pages9
JournalArchives of Biochemistry and Biophysics
Issue number1
Publication statusPublished - Dec 1 2000


  • Apoptosis
  • Cytochrome c
  • Disulfide bonds
  • Hsp90
  • Molecular chaperone
  • Sulfhydryl groups

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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