Haack T, Camarero J A, Roig X, Mateu M G, Domingo E, Andreu D, Giralt E
Department of Organic Chemistry, University of Barcelona, Spain.
Int J Biol Macromol. 1997 Jun;20(3):209-19. doi: 10.1016/s0141-8130(97)01163-x.
A cyclic disulfide peptide corresponding to the G-H loop sequence 134-155 [replacement Tyr136 and Arg153 with Cys] of the capsid protein VP1 of foot-and-mouth disease virus (FMDV) isolate C-S8c1 was examined by proton 2D-NMR spectroscopy in water and in 25% HFIP/water. In water, NMR data supported the presence of a non-canonical turn in the central, conserved cell adhesion RGD motif and suggested the presence of a nascent helix in the C-terminal part, stabilized and slightly extended upon addition of 25% HFIP, a secondary structure stabilizing cosolvent. The formation of the C-terminal helix was evidenced by combined analysis of NOE connectivities, H alpha chemical shifts, 3JNH-H alpha coupling constants and amide temperature coefficients. Surprisingly, these global structural features of the cyclic peptide in solution show similarities to previous X-ray structure analysis of (a) a shortened linear peptide complexed with a antivirus antibody and (b) the G-H loop represented on the chemical reduced viral surface of a different serotype. Thus, even in entirely different biological environments the cyclic peptide reflect similar structural features, reinforcing the concept that this viral loop behaves as an independent structural and functional unit.
对口蹄疫病毒（FMDV）分离株C-S8c1衣壳蛋白VP1的G-H环序列134-155（用半胱氨酸取代Tyr136和Arg153）对应的环状二硫键肽，在水和25%六氟异丙醇/水体系中通过质子二维核磁共振光谱进行了检测。在水中，核磁共振数据支持在中央保守的细胞黏附RGD基序中存在一个非典型转角，并表明在C端部分存在一个新生螺旋，在添加25%六氟异丙醇（一种二级结构稳定共溶剂）后该螺旋得到稳定并略有延伸。通过对核Overhauser效应（NOE）连接性、Hα化学位移、3JNH-Hα耦合常数和酰胺温度系数的综合分析，证实了C端螺旋的形成。令人惊讶的是，该环状肽在溶液中的这些整体结构特征与之前对以下两种情况的X射线结构分析结果相似：（a）与抗病毒抗体复合的缩短线性肽；（b）不同血清型化学还原病毒表面上呈现的G-H环。因此，即使在完全不同的生物环境中，该环状肽也反映出相似的结构特征，强化了这种病毒环作为一个独立结构和功能单元的概念。
