The Thermodynamic Evidence of Two Native Conformations Coexisting in Solution For Apoazuirn: a DSC and CD Study
- VernacularTitle:去辅基天青蛋白两种天然构象共存的热力学证据 --差热温度扫描和圆二色的研究
- Author:
Hongjie ZHANG
- Publication Type:Journal Article
- Keywords:
thermal unfolding;
apoazurin;
differential scanning calorimetry;
circular dichnoism;
protein conformation
- From:
Progress in Biochemistry and Biophysics
2005;32(3):239-244
- CountryChina
- Language:Chinese
-
Abstract:
Whether protein could adopt multiple conformations coexisting in solution is disputable. In a previous report,the conformation heterogeneity of apoazurin mutant M121L had been identified. The thermal unfolding of wild type apoazurin from Pseudomonas aeruginosa is re-investigated with differential scanning calorimetry (DSC) and circular dichroism (CD) methods. The results show that unfolding in the pH range from 4 to 9 is associated with two heat capacity maxima. The low temperature transitions are reversible at all pH conditions used, while the high temperature transitions are irreversible. The two unfolding transitions were analyzed by the two-interchangeable-conformation model with the fraction for the first transition (N1) from 64% at pH 4.0 to 55% at pH 9.0. Temperature induced unfolding monitored at 219 nm shows also two separate transitions. The ratio of the signal changes is consistent with the fractions obtained from the corresponding DSC measurements. These results provide further support for the hypothesis that at least two conformations of apoazurin coexists in solution.
