Temperature dependence of the thermodynamics of helix-coil transition |
| |
Authors: | Richardson John M Makhatadze George I |
| |
Institution: | Department of Biochemistry and Molecular Biology H171, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033-2390, USA. |
| |
Abstract: | The temperature-induced helix to coil transition in a series of host peptides was monitored using circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC). Combination of these two techniques allowed direct determination of the enthalpy of helix-coil transition for the studied peptides. It was found that the enthalpy of the helix-coil transition differs for different peptides and this difference is related to the difference in the temperature for the midpoint of helix-coil transition. The enthalpy of the helix-coil transition decreases with the increase in temperature, thus providing the first experimental estimate for the heat capacity changes upon helix-coil transition, DeltaC(p). The values for DeltaC(p) of helix-coil transition are found to be negative, which is in contrast to the positive DeltaC(p) for protein unfolding. Analysis suggests that this negative DeltaC(p) of helix-coil transition is due to the exposure of the polar peptide backbone to solvent upon helix unfolding. |
| |
Keywords: | CD DSC helix-coil transition enthalpy ΔCp |
本文献已被 ScienceDirect PubMed 等数据库收录! |