Studies on the conformational properties of CP-10(42-55), the hinge regionof CP-10, using circular dichroism and RP-HPLC

The conformational properties of Cp-10(42-55), a peptide corresponding to t he hinge region of CP-10, were investigated using circular dichroism spectr oscopy and reverse-phase highperformance liquid chromatography (RP-HPLC). T he circular dichroism studies indicated that Cp-10(42-55) formed considerab le secondary structure in the presence of hydrophobic solution environments including 50% acetonitrile, 50% trifluoroethanol and 200 mM sodium dodecyl sulfate, which comprised a mixture of alpha-helix and beta-sheet. The effe ct of temperature on the conformation of Cp-10(42-55) was investigated betw een 5 and 40 degrees C, with very small changes in the spectra being observ ed. RP-HPLC was then used to investigate the effect of temperature on the c onformation of Cp-10(42-55) in the presence of a hydrophobic surface. Using a Cls-adsorbent, Cp-10(42-55) exhibited a conformational transition at 25 degrees C which was associated with an increase in the chromatographic cont act area and the binding affinity of the peptide for the stationary phase. In addition, near-planar bandbroadening behaviour indicated that conformati onal species interconverted with rapid rate constants compared with the chr omatographic time scale. These results indicated that the conformational ch ange at 25 degrees C in the RP-HPLC system most likely corresponds to the u nfolding of an alpha-helical and/or beta-sheet structure to an extended coi l structure. Therefore, the strong chemotactic properties of this peptide m ay be attributed to its ability to form considerable secondary structure in the presence of a hydrophobic environment.