Quantitation of the interaction of the immunosuppressant deoxyspergualin and analogs with Hsc70 and Hsp90.
Deoxyspergualin (DSG), a spermidinyl, alpha-hydroxyglycyl, 7-guanidinoheptanoyl peptidomimetic, shows immunosuppressive activity. In confirmation of a recent report that immobilized methoxyDSG selectively retains the heat shock protein Hsc70, we report here quantitative binding of DSG and analogs to both Hsc70 and the 90-kDa heat shock protein Hsp90. We have utilized affinity capillary electrophoresis to obtain Kd values for DSG and analogs, and stimulation of the ATPase activity of Hsc70 to obtain Km values for DSG, that are comparable and corroborative. Kd values are 4 microM for DSG binding to Hsc70 and 5 microM for DSG binding to Hsp90. Two active analogs, methoxy- and glycylDSG, bind with similar affinities. Glyoxylylspermidine and des(aminopropyl)DSG, two inactive metabolites, have much reduced affinity for Hsc70 and Hsp90. These data validate binding of these novel immunosuppressant agents to these molecular chaperones, at concentrations in the range of pharmacologically active doses, and indicate that further characterization of Hsc70 and/or Hsp90 as potential targets for DSG is warranted.
Nadeau
K
K
Department of Biological Chemistry, Harvard Medical School, Boston, Massachusetts 02138.
Nadler
S G
SG
Saulnier
M
M
Tepper
M A
MA
Walsh
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CT
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000737:chemistry*; D002417:Cattle; D006146:Guanidines / Q000737:chemistry*; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry*; D006801:Humans; D007166:Immunosuppressive Agents / Q000737:chemistry*; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D013329:Structure-Activity Relationship; D014349:Trypanosoma cruzi
D002352:Carrier Proteins; D006146:Guanidines; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494371:HSPA8 protein, human; D006360:Heat-Shock Proteins; C494372:Hspa8 protein, mouse; D007166:Immunosuppressive Agents; D010455:Peptides; D000251:Adenosine Triphosphatases; C037258:gusperimus