Use of Steric Interactions To Control Peptide Turn Geometry. Synthesis of Type VI β-Turn Mimics with 5-<i>tert</i>-Butylproline
作者:Liliane Halab、William D. Lubell
DOI:10.1021/jo990294a
日期:1999.4.1
DMSO, and water by proton NMR spectroscopy. Although the trans-amide isomer was favored in prolyl peptide 2, the Xaa-Pro peptide bond adopted preferably the cis-amide isomer in the case of 5-tert-butylprolyl peptide 1. Measurements of the influence of solvent and temperature on the chemical shift values for the amide proton signals of 1 in the cis-amide conformer indicated that the N'-methylamide was
研究了空间相互作用对肽几何形状的影响,以开发出一种新型的产生VIa型β-turn模拟物的方法。(2S,5R)-5-叔丁基脯氨酸和L-脯氨酸分别引入N-(乙酰基)二肽N'-甲基酰胺1和2的C端残基。脯氨酰顺酰胺和反酰胺的相对种群通过质子NMR光谱法在氯仿,DMSO和水中测量二肽1和2中的异构体。尽管脯氨酰肽2倾向于使用反酰胺异构体,但在5-叔丁基脯氨酰肽1的情况下,Xaa-Pro肽键优选采用顺酰胺异构体。测量溶剂和温度对化学位移的影响顺式酰胺构象的酰胺质子信号值为1表示N' -甲基酰胺与乙酰胺羰基以VIaβ-转构型进行氢键键合。通过X射线衍射分析固态的N-(乙酰基)亮氨酰-5-叔丁基脯氨酸N'-甲基酰胺(1d)显示顺式酰胺构象异构体采用了中心i + 1和i的几何特征+ 2个理想VIa型β-残基的残基。与脯氨酰肽2b和2d相比,N-(乙酰基)丙氨酰和N-(乙酰基)亮氨酰基-5-叔丁基脯氨酸N'