鸡心脱辅基细胞色素c自发折叠的进一步研究

将野生型鸡心脱辅基细胞色素ｃ及其突变体Ｖ９２Ａ的１７位半胱氨酸残基突变为丝氨酸，再将表达纯化的Ｖ９２Ａ／Ｃ１７Ｓ和Ｗ／Ｃ１７Ｓ用荧光探针ＩＡＥＤＡＮＳ标记．通过测量ＡＥＤＡＮＳ－Ｃｙｓ－１４的荧光光谱、荧光寿命以及ＡＥＤＡＮＳ与Ｔｒｐ－５９之间的荧光共振能量转移效率、比较了Ｖ９２Ａ与野生型鸡心脱辅基细胞色素ｃ因折叠状态不同引起的Ｎ端构象状态及肽链间相互作用的差异．结果显示Ａｐｏ．ｃ无论在低盐浓度下的无规卷曲状态还是高盐浓度下的融球态，Ｖ９２Ａ都较野生型处于更松散的折叠状态，此外，在鸡心脱辅基细胞色素ｃ的自发折叠中Ｎ端肽段并不起主要作用

Further Study on the Spontaneous Folding of Chicken Apocytochrome c

It has been reported that chicken heart apocytochrome c has been shown to possess a much stronger tendency to fold spontaneously in aqueous solution than the equivalent from other species and V92A could alter the folding propensity of chicken apocytochrome c and its interaction with phospholipid.In order to further study the conformation difference between wild type of chicken heart apocytochrome c and its V92A mutant,two mutants,W/C17S and V92A/C17S,in which the 17 cysteine residue was replaced by serine were obtained and expressed in E.coli .By using fluorescence probe IAEDANS(reacted on the SH group of 14 cystein residue) the conformation and that of intramolecular interactions between W/C17S and V92A/C17S were investigated by AEDANS fluorescence emission spectra,fluorescence lifetime and fluorescence energy transfer efficiency.Obtained results showed that comparing with the wild type of chicken heart apocytochrome c the V92A mutant appeared less folded state both in the presence and absence of 5 0 mol/L NaClO 4.It also seemed that the N terminal of the chicken heart apocytochrome c might not be involved during its spontaneous folding.