FOLDING OF PEPTIDE-FRAGMENTS COMPRISING THE COMPLETE SEQUENCE OF PROTEINS - MODELS FOR INITIATION OF PROTEIN FOLDING .1. MYOHEMERYTHRIN
FOLDING OF PEPTIDE-FRAGMENTS COMPRISING THE COMPLETE SEQUENCE OF PROTEINS - MODELS FOR INITIATION OF PROTEIN FOLDING .1. MYOHEMERYTHRIN
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DOI：
10.1016/0022-2836(92)90633-u
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发表时间：
1992-08-05
影响因子：
5.6
通讯作者：
WRIGHT, PE
中科院分区：
文献类型：
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作者：
DYSON, HJ;MERUTKA, G;WRIGHT, PE
为了描述不同蛋白质结构基序的潜在折叠起始位点，我们合成了一系列跨越两种蛋白质多肽链整个长度的肽，并使用质子核磁共振和圆二色光谱检测了它们在水溶液中的构象偏好。我们在这里描述了从一个简单的四螺旋束蛋白，肌赤氰菊酯衍生的肽的行为。这些肽对应于四个长螺旋（A、B、C和D螺旋）、N端和C端环以及螺旋之间的连接序列。与折叠蛋白的螺旋相对应的肽在溶液中都表现出螺旋状构象的偏好。a -和d -螺旋肽的构象集合包含有序的螺旋形式，这表明了一系列广泛的中程核Overhauser效应连接，而B-和c -螺旋肽表现出对新生螺旋的构象偏好。在三氟乙醇和水的混合物中，所有四种肽都采用有序的螺旋构象。末端和相互连接的环状肽在α-区也含有大量的主链φ和ψ角的构象，在某些情况下还包括大量的疏水簇和/或转构象。三氟乙醇不能使这些肽形成螺旋构象。总体而言，肌氰菊酯的肽片段在水溶液中具有明显的二级结构形成倾向。相反，从β-三明治蛋白质体青素衍生的肽片段在水溶液中相对缺乏二级结构（见随附论文）。这些结果表明，两种不同的蛋白质结构基序可能需要不同的形成二级结构局部元素的倾向来启动折叠，并且存在由局部氨基酸序列决定的构象空间的预分配，而螺旋结构基序和β-三明治结构基序不同。
In an attempt to delineate potential folding initiation sites for different protein structural motifs, we have synthesized series of peptides that span the entire length of the polypeptide chain of two proteins, and examined their conformational preferences in aqueous solution using proton nuclear magnetic resonance and circular dichroism spectroscopy. We describe here the behavior of peptides derived from a simple four-helix bundle protein, myohemerythrin. The peptides correspond to the sequences of the four long helices (the A, B, C and D helices), the N- and C-terminal loops and the connecting sequences between the helices. The peptides corresponding to the helices of the folded protein all exhibit preferences for helix-like conformations in solution. The conformational ensembles of the A-and D-helix peptides contain ordered helical forms, as shown by extensive series of medium-range nuclear Overhauser effect connectivities, while the B- and C-helix peptides exhibit conformational preferences for nascent helix. All four peptides adopt ordered helical conformations in mixtures of trifluoroethanol and water. The terminal and interconnecting loop peptides also appear to contain appreciable populations of conformers with backbone φ and ψ angles in the α-region and include highly populated hydrophobic cluster and/or turn conformations in some cases. Trifluoroethanol is unable to drive these peptides towards helical conformations. Overall, the peptide fragments of myohemerythrin have a marked preference towards secondary structure formation in aqueous solution. In contrast, peptide fragments derived from the β-sandwich protein plastocyanin are relatively devoid of secondary structure in aqueous solution (see accompanying paper). These results suggest that the two different protein structural motifs may require different propensities for formation of local elements of secondary structure to initiate folding, and that there is a prepartitioning of conformational space determined by the local amino acid sequence that is different for the helical and β-sandwich structural motifs.