猴金属硫蛋白MT1 α-结构域中Cys33和Cys34的突变对蛋白质稳定性的影响

重组猴金属硫蛋白MT1及其C33M,C34S和C33M/C34S突变体蛋白的蛋白质快速液相色谱(FPLC)分析表明,突变体蛋白C34S和C33M/C34S存在着两个稳定的流分f1和f2.CD光谱和重金属离子分析表明,突变体蛋白多流分不仅与半胱氨酸和Cd2+离子结合方式和构型有关,还与金属结合量有关.突变体蛋白多流分的结果表明,在把猴金属硫蛋白α-结构域中的Cys33和Cys34突变为非半胱氨酸残基以建立β-β结构域的金属硫蛋白时,可导致蛋白形成多种结构形式.这表明α-结构域在稳定金属硫蛋白的结构中起着重要的作用,半胱氨酸残基在肽链上的分布对金属硫蛋白的三级结构和金属硫簇的形成有重大的影响.

Effect of Mutation of Cys33 and Cys34 in the α-Domain of Monkey Metallothionein-1 on the Protein Stability

FPLC analysis of the recombinant protein of monkey metallothionein, MT1 and its C33M, C34S and C33M/C34S mutants shows that there were two stable components, f1 and f2. CD study and metal ion analyses indicate that multi components of the mutants relates not only to the binding mode and configuration between cysteins and cadmiun ions, but also to the number of the metal ions. This result also demonstrates that when the Cys33 and Cys34 of α domain of monkey metallothion were mutated into non cystein residues in an attempt of creating a metallothionein with β β domain structure, it led to a protein with multiple structures. It indicates that the α domain plays an important role in the protein stability, and also the distribution of cystein residues affects the formation of metal thiolate clusters and the tertiary structure of the protein significantly.