Studies of peptides forming 3(10)- and alpha-helices and beta-bend ribbon structures in organic solution and in model biomembranes by Fourier transform infrared spectroscopy.
Studies of peptides forming 3(10)- and alpha-helices and beta-bend ribbon structures in organic solution and in model biomembranes by Fourier transform infrared spectroscopy.
复制标题
通过傅里叶变换红外光谱研究有机溶液和模型生物膜中形成 3(10)-和 α-螺旋以及 β-弯曲带结构的肽。
作者：
D. F. Kennedy;M. Crisma;C. Toniolo;D. Chapman
为了检验红外吸收光谱与3(10)-和α -螺旋和β -弯曲带结构之间的潜在相关性，基于x射线衍射和核磁共振研究，利用FTIR光谱结合分辨率增强技术研究了已知含有纯3(10)-螺旋、混合3(10)/ α -螺旋和纯β -弯曲带结构的合成肽的二级结构。对已知在CDCl3中含有稳定3(10)-螺旋的肽的研究表明，完全稳定的3(10)-螺旋的主要酰胺I带发生在1666-1662 cm-1。分辨率增强方法在1681 ~ 1678和1646 ~ 1644 cm-1波段贡献较小，而酰胺II波段出现在1533 ~ 1531 cm-1波段。已知在其结构中含有α -和3(10)-螺旋的肽显示出两种类型构象的特征带。已知折叠成β弯曲带结构的肽显示酰胺I带在1648-1645 cm-1处最大，酰胺II带在1538-1536 cm-1处最大。将这些肽掺入模型膜结构中，例如，在水缓冲液中DMPC囊泡，有时会产生肽二级结构的变化。那些在CDCl3溶液中具有3（10）螺旋结构的肽改变了DMPC囊泡中的二级结构，主要是α -螺旋结构，加上短的，不稳定的3（10）螺旋和/或β -螺旋的贡献。那些含有α -和3(10)-螺旋结构的肽在CDCl3溶液中倾向于在脂质环境中保留一些3(10)-螺旋结构，尽管整个氢键模式被改变。那些形成β弯曲带结构的肽在膜环境中似乎基本不受影响。（摘要删节250字）
In order to examine the potential correlation between infrared absorption spectra and 3(10)- and alpha-helices and beta-bend ribbon structures, the secondary structures of synthetic peptides known to contain pure 3(10)-helices, mixed 3(10)/alpha-helices, and pure beta-bend ribbon structures, based upon X-ray diffraction and NMR studies, have been investigated by using FTIR spectroscopy incorporating resolution-enhancement techniques. Studies of the peptides known to contain a stable 3(10)-helix in CDCl3 show the main amide I band of fully stable 3(10)-helices occurs at 1666-1662 cm-1. Resolution-enhancement methods revealed small contributions at 1681-1678 and 1646-1644 cm-1, while the amide II band occurs at 1533-1531 cm-1. Peptides known to contain both alpha- and 3(10)-helices in their structure exhibit bands characteristic of both types of conformation. Peptides known to fold into the beta-bend ribbon structure show an amide I band maximum at 1648-1645 cm-1 with the amide II band at 1538-1536 cm-1. Incorporation of these peptides into model membrane structures, e.g., DMPC vesicles, in aqueous buffer sometimes produces changes in the peptide secondary structure. Those peptides which possess a 3(10)-helical structure in CDCl3 solution change the secondary structure in DMPC vesicles to predominantly alpha-helical, plus a contribution from short, unstable 3(10)-helix and/or beta-turns. Those peptides which contain a combination of alpha- and 3(10)-helical structures in CDCl3 solution tend to retain some 3(10)-helical structure within the lipid environment, although the overall H-bonding pattern is altered. Those peptides which form a beta-bend ribbon structure appear to be largely unaffected in the membrane environment.(ABSTRACT TRUNCATED AT 250 WORDS)