CD and FTIR spectroscopic studies of Amadori compounds related to the opioid peptides
作者:Štefica Horvat、Andreja Jakas、Elemér Vass、János Samu、Miklós Hollósi
DOI:10.1039/a700499k
日期:——
Circular dichroism (CD) and Fourier transform infrared (FTIR)
spectroscopy have been used to investigate conformational effects of
glycation on the secondary structure of opioid peptide Leu-enkephalin
and on structurally related peptides in 2,2,2-trifluoroethanol (TFE)
solution. CD spectral analysis of Leu-enkephalin-related Amadori
compounds revealed that attachment of the protected or free sugar may
influence not only the distribution of the backbone but also the
side-chain conformation of the Tyr moiety. The amide I region of the
FTIR spectra analysed by self-deconvolution and curve-fitting methods
revealed that Leu-enkephalin is present as a mixture of
β-sheet and γ-turn conformers in TFE
solution, while its methyl ester likely adopts a β-turn
conformation. FTIR spectroscopy has shown that no major spectral changes
occur in the peptide part of glycated (Amadori) compounds as compared to
parent peptides. The structurally related Tyr-Gly-Gly tripeptide
derivatives contain amide I components at ca. 1630 and ca.
1645 cm-1 consistent with the presence of
γ-turns with strong and weak 1 â†� 3
H-bondings, respectively. The attachment of the protected or free sugar
moiety to pentapeptides appears to destabilize β-turns but
not to affect H-bonded γ-turns. In the spectra of Amadori
compounds containing a free sugar moiety, the component band at ca.
1730 cm-1 suggests the presence of the open-chain
sugar form. Based on the studies presented herein, FTIR spectroscopy is
shown to be a powerful tool for the structural analysis of glycated
peptides, in particular for the detection of the keto form of the sugar
and turn conformations of the peptide part of the molecule.
圆二色性 (CD) 和傅里叶变换红外 (FTIR)
光谱学已被用来研究构象效应
阿片肽亮氨酸脑啡肽二级结构的糖化
以及 2,2,2-三氟乙醇 (TFE) 中结构相关的肽
解决方案。亮氨酸脑啡肽相关的 Amadori 的 CD 光谱分析
化合物表明,受保护糖或游离糖的附着可能
不仅影响骨干的分布,
Tyr 部分的侧链构象。酰胺 I 区
通过自解卷积和曲线拟合方法分析 FTIR 光谱
表明亮氨酸脑啡肽以混合物形式存在
TFE 中的 β-折叠和 γ-转角构象异构体
溶液,而其甲酯可能采用β-转角
构象。 FTIR 光谱显示没有重大光谱变化
与相比,发生在糖化(Amadori)化合物的肽部分
母肽。结构相关的 Tyr-Gly-Gly 三肽
衍生物含有约 酰胺 I 组分。 1630 和约。
1645 cm-1 与存在一致
强弱 γ 转弯 1 → 3
分别为H键。受保护糖或游离糖的附着
五肽的部分似乎会破坏β-转角的稳定性,但
不影响氢键γ-转角。在阿马多里的光谱中
含有游离糖部分的化合物,其组分带位于约。
1730 cm-1 表明存在开链
糖形式。根据本文提出的研究,FTIR 光谱法
被证明是糖化结构分析的有力工具
肽,特别是用于检测糖的酮形式
并转动分子肽部分的构象。