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双胞胎 2JCCH 旋转-旋转合常数作为在寡糖体中的 phi 甘油酸扭转角度的探测器
Thomas E Klepach1, Ian Carmichael, Anthony S Serianni
1Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556-5670, USA.
Journal of the American Chemical Society
|July 7, 2005
概括
在 aldopyranosyl 环中的双键碳NMR 合物 ((2) J ((CCH)) 受 C-O 扭曲的影响. 新的方程解释了这些合,帮助NMR结构分析的寡糖.
科学领域:
- 计算化学的计算化学
- 核磁共振光谱学 核磁共振光谱学
- 碳水化合物化学 碳水化合物化学
背景情况:
- 双键 (13) C-(1) H NMR 旋转合常数 ((2) J(CCH)) 对 aldopyranosyl 环中的立体化学敏感.
- 之前的研究表明,依赖于替代品定向和C-O扭曲.
研究的目的:
- 从理论上阐明 (2) J ((C2,H1) 和 (2) J ((C1,H2) 在 aldopyranosyl 环中对 C-O 扭转角度 (phi 和 alpha) 的依赖.
- 开发新的参数化方程来解释这些NMR合.
- 评估 (2) J (((C2,H1) 作为一种NMR结构约束对甘氨酸结合的有用性.
主要方法:
- 密度函数理论 (DFT) 的计算在模型 pyranosyl 环上进行.
- 计算探讨了C1和C2的四个相对配置,包括一个2-脱氧衍生物.
- 计算的J-合被验证与实验测量.
主要成果:
- (2) J ((CCH) 表示主要依赖于携带合质子的碳的C-O扭矩,并对合碳的C-O扭矩产生次要依赖.
- 氧单双对键长度的影响显著影响合路径.
- 对于 (2) J ((C1,H2) 和 (2) J ((C2,H1) 的新参数化方程得到了推导.
结论:
- 导出方程为解释 (2) J ((CCH) 在 aldopyranosyl 系统中提供了一个框架.
- 方程 (2)J(C2,H1) 对于确定 C1-O1 扭矩角度 (phi) 在寡糖中特别有价值.
- 这项工作增强了NMR光谱在碳水化合物结构阐明中的应用.
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