| Abstrakt: |
Utilizing the ratio of the fluorescence intensities of the reduced and oxidized forms of horse heart cytochrome c(cyt c), it is possible to monitor conformational changes of the protein upon reduction. The temperature dependence from 25 to 50°C of the ratio is sigmoidal in nature, indicative of a conformational transition with the midpoint being 43°C in 0.10 mNaCl, 0.10 mPO4buffer, pH 7.0, solution. This transition is consistent with the previously postulated biphasic model used to explain the nonlinearity in EO′vs Tin Cl−−H2O solutions [C. W. Anderson, H. B. Halsall, W. R. Heineman, and G. P. Kreishman (1977)Biochem. Biophys. Res. Commun.76, 339–344]. In addition, the chemical shift of the bulk water proton in tetramethylammonium chloride solution shows a nonlinearity at 42°C and it is postulated that the conformational changes of cyt care the result of the behavior of the bulk water structure. |
