FOLDING OF IMMUNOGENIC PEPTIDE-FRAGMENTS OF PROTEINS IN WATER SOLUTION .2. THE NASCENT HELIX
FOLDING OF IMMUNOGENIC PEPTIDE-FRAGMENTS OF PROTEINS IN WATER SOLUTION .2. THE NASCENT HELIX
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DOI：
10.1016/0022-2836(88)90447-0
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发表时间：
1988-05-05
影响因子：
5.6
通讯作者：
LERNER, RA
中科院分区：
文献类型：
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作者：
DYSON, HJ;RANCE, M;LERNER, RA
1H核磁共振实验表明，对应于肌红蛋白的C螺旋（残基69至87）的序列EVVPHKKMHKDFLEK-IGGL的合成免疫原性肽的水溶液中形成二级结构。构象整体由一组类似转弯的结构组成，分布在肽的 C 端一半上，并通过未折叠状态快速相互转换。这些结构被称为新生螺旋，在水/三氟乙醇混合物中稳定成具有长程有序的螺旋结构。圆二色性测量证实了水/三氟乙醇中存在 50% 螺旋，但没有显示肽水溶液中存在螺旋性的证据。显然，构成新生螺旋的瞬时螺旋构象组中没有一个成员足够长，无法通过圆二色性实验检测到。无论是在水还是水/三氟乙醇混合物中，通过核磁共振均未检测到肽的 N 末端一半的优选构象。肽的该区域通过折叠蛋白中的长程相互作用而稳定在螺旋中。讨论了新生二级结构在抗肽抗体诱导和蛋白质折叠起始中的可能作用。
1H nuclear magnetic resonance experiments indicate formation of secondary structures in water solutions of a synthetic immunogenic peptide of sequence EVVPHKKMHKDFLEK-IGGL corresponding to the C-helix (residues 69 to 87)of myohemerythrin. The conformational ensemble consists of a set of turn-like structures, distributed over the C-terminal half of the peptide and rapidly interconverting by way of unfolded states. These structures, termed nascent helix, are stabilized into helical structure with long-range order in water/trifluorethanol mixtures. Circular dichroism measurements confirm the presence of 50% helix in water/trifluoroethanol but show no evidence of helicity in water solutions of the peptide. It is apparent that no one member of the transient set of helical conformations which constitutes the nascent helix is sufficiently long to be detectable by circular dichroism experiments. No preferred conformations could be detected by nuclear magnetic resonance in the N-terminal half of the peptide, either in water or water/trifluoroethanol mixtures. This region of the peptide is stabilized in helix by long-range interactions in the folded protein. The possible role of nascent secondary structure in induction of antipeptide antibodies and in initiation of protein folding is discussed.