| 细胞色素b5 S64X突变体对蛋白结构及稳定性的影响 |
| Effect of Mutation at Ser64 on the Structure and Stability of Cytochrome b5 |
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| 摘要: 为了深入了解细胞色素b5(Cyt b5)64位氨基酸残基(Ser64)对血红素辅基微环境及蛋白性质的影响，我们分别对Cyt b5 Ser64进行了保守性突变(S64T)以及非保守性突变(S64K、S64N和S64H)，均为亲水性氨基酸残基。对野生型细胞色素b5及其突变体蛋白S64X(X：T，K，N或H)的热、酸、盐酸胍变性的稳定性研究表明：4个突变体蛋白的稳定性相对于野生型都大大降低了；CD光谱表明，细胞色素b5 S64X突变体中的α-螺旋明显减少，芳香性氨基酸残基所处的肽链结构受到了影响；盐酸胍变性荧光光谱表明，Trp22周围的蛋白肽链受到了影响，Trp22暴露于水溶液的程度加大。我们认为Ser64不仅对血红素辅基有稳定作用，同时还对维持蛋白Core 1中的第5个α-螺旋结构有重要的作用，在64位引入其他氨基酸残基影响了第5个α-螺旋的结构，并通过蛋白肽链的相互作用，使得Trp22所在的Core 2结构也受到了较为明显的扰动。 |
| 关键词: 细胞色素b5 Ser64突变体 稳定性 α-螺旋 血红素 |
| 基金项目: |
| Abstract: To understand the influence of Ser64 on the structure and stability of cytochrome b5, a study was made for the conserved mutation in cytochrome b5 S64T, and non-conserved mutations in the cytochrome b5 S64K, S64N and S64H mutant proteins, in which all substitutes are hydrophilic amino acids. The UV-Vis spectroscopy, CD spectra, and stability studies were done to find out the changes of structures and stabilities. The stability studies of wild type cytochrome b5 and its S64X (X: T, K, N or H) mutants show that, the stabilities of S64X mutant decrease distinctly. CD spectra show the percentage of α-helix decreases obviously, and fluorescence spectra reflect the disturbance of the polypeptide around Trp22. These results show that, Ser64 is very important for maintaining structure of the fifth α-helix, and could disturb the Core 2, which leads to the decrease of the mutant protein structural stability. |
| Keywords: cytochrome b5 cyt b5 Ser64 mutation stability α-helix heme |
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| 官墨蓝,王中华,林英武,黄仲贤.细胞色素b5 S64X突变体对蛋白结构及稳定性的影响[J].无机化学学报,2008,24(1):47-54. |
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