Search

The proteasome and heat shock proteins have been found in the centrosome. The evidence of their copurification reported by several studies suggests that they form stable complex. In addition, Hsp90 is involved in the loading of proteasome‐generated antigenic peptides to the class I major histocompatibility complex. In this article, we report a detailed thermodynamic and kinetic characterization of the Hsp90‐20S proteasome interaction, using a surface plasmon resonance technique. The modulation exerted by protons in solution has been investigated, and the results have been discussed, taking into account structural motifs characterizing the binding interface between the two macromolecules. Proteins 2002;48:169–177. © 2002 Wiley‐Liss, Inc.

The clotting activity of human fibrinogen was fully inhibited in vitro by peroxynitrite. The decrease of activity followed an exponential function and the concentration of peroxynitrite needed to inhibit 50% of fibrinogen clotting was 22 μM at 25°C. The oxidative modification(s) induced by the peroxynitrite system (i.e. ONOO−, ONOOH and ONOOH*) appeared specifically to affect fibrin clot formation (through the inhibition of fibrinogen polymerization) since the interaction of peroxynitrite‐modified fibrinogen with thrombin appeared to be unaffected. The addition of NaHCO3decreased the peroxynitrite effect on fibrinogen clotting, suggesting that the reactive species formed by the reaction of CO2with peroxynitrite are less efficient oxidants of peroxynitrite itself. Similar effects were observed after addition of bilirubin, which also exerted a significant protection against peroxynitrite‐mediated modification of fibrinogen.

The clotting activity of human fibrinogen was fully inhibited in vitro by peroxynitrite. The decrease of activity followed an exponential function and the concentration of peroxynitrite needed to inhibit 50% of fibrinogen clotting was 22 μM at 25°C. The oxidative modification(s) induced by the peroxynitrite system (i.e. ONOO −, ONOOH and ONOOH*) appeared specifically to affect fibrin clot formation (through the inhibition of fibrinogen polymerization) since the interaction of peroxynitrite-modified fibrinogen with thrombin appeared to be unaffected. The addition of NaHCO 3decreased the peroxynitrite effect on fibrinogen clotting, suggesting that the reactive species formed by the reaction of CO 2with peroxynitrite are less efficient oxidants of peroxynitrite itself. Similar effects were observed after addition of bilirubin, which also exerted a significant protection against peroxynitrite-mediated modification of fibrinogen.