Structural organization in peptide fragments of cytochrome c by heme binding.
Structural organization in peptide fragments of cytochrome c by heme binding.
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通过血红素结合进行细胞色素 c 肽片段的结构组织。
DOI：
10.1006/jmbi.1998.2341
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Carey,J
中科院分区：
文献类型：
--
作者：
Kang,X;Carey,J
假体基团通常是蛋白质的重要结构组织者，也是重要的功能成分。修复基团的插入通常是自发的，并暗示了一种部分预先组织的脱辅蛋白，为特定结合提供了识别表面。细胞色素c的不同之处在于，其血红素通过硫醚连接到半胱氨酸侧链上，由专用的血红素裂解酶连接，在生理条件下，脱脂蛋白没有表现出前组织的证据。然而，将血红素添加到细胞色素c的两个短片段中，显著增强了螺旋结构(从∼8%到∼22%)，这一效果依赖于铁连接而不是硫醚键。天然全蛋白相应部分的螺旋片段与血红素的接触表面很小，这意味着片段复合体中增加的螺旋结构可能依赖于三级相互作用。中间多肽链的缺失表明该复合体代表了一个相对独立的折叠亚域。
Prosthetic groups are often important structural organizers of proteins as well as essential functional components. Insertion of prosthetic groups is usually spontaneous, and implies an apoprotein that is partially preorganized to provide a recognition surface for specific binding. Cytochrome c is distinguished by having its heme attached by a dedicated heme lyase through thioether links to cysteine side-chains, and the apoprotein shows no evidence of preorganization under physiological conditions. Nevertheless, addition of heme to two short fragments of cytochrome c enhances helical structure substantially (from ∼8 % to ∼22 %), an effect that depends on iron ligation but not thioether linkage. The helical segments in the corresponding parts of the native holoprotein have little contact surface with heme, implying that the increased helical structure in the fragment complex may depend on tertiary interactions. The absence of the intervening polypeptide chain suggests that the complex represents a relatively independent folded subdomain.