MEMBRANE PEPTIDE STRUCTURE VIA NMR & QUANTUM CHEMISTRY

SIR提供L-[2- 13 C]色氨酸; 2g L-13- 13 C]色氨酸; 1.25g该项目背后的想法是使 13 C标记的短杆菌肽，作为原型膜穿透 肽/蛋白质片段，并探索其结构使用 各向同性碳-13化学位移，加上量子化学， 结构的探测。 以前的工作一直集中在定向 (15N，2 H，一些13 C）信息-一条线在一个 定向样品，而不是完全分析化学位移 使用量子化学，这就是我们在这里提出的。 的能力 从结构上分析蛋白质的各向同性化学位移 有很好的机会使更多的系统能够适应 短杆菌肽中Trp的Ca、Cb、Cg含量最高 探针（特别是因为Trps具有重要的功能）。 通过 将观察到的各向同性化学位移与量子 化学计算的屏蔽表面，一个获得的色氨酸， c 1、c 2以及f、y、c 1的解得到瓦尔、Leu的结果。这些 独特的解决方案消除了可能与偶极或 四极导出几何约束，当与 通常更精确（但多值）的张量数据应该产生非常 精确的，独特的NMR解决方案，对于f，y，c1，c2。 Trp知识 方向对于理解短杆菌肽的作用很重要， 以上结果（连同）我们计划取得的结果， 市售的13 C甘氨酸和丙氨酸）应一起 清楚地表明化学位移在结构研究中的效用， 特别是化学位移在某种意义上 基本核磁共振性质。

The SIR provided L-[2- 13 C]Tryptophan; 2g L-13- 13C]Tryptophan; 1.25g The idea behind this project is to make 13C-labeled gramicidins, as prototypical membrane penetrating peptide/protein fragments, and to explore their structure using the ISOTROPIC CARBON- 13 CHEMICAL SHIF'F, plus quantum chemistry, as a probe of structure. Previous work has always focused on orientational (15N, 2H, some 13C) information - the position of a line in an oriented sample, rather than completely analyzing chemical shifts using quantum chemistry, which is what we propose here. The ability to analyze isotropic chemical shifts in proteins in structural terms has a good chance of making may more systems amenable to investigation, and Ca, Cb, Cg of Trp in gramicidin should be excellent probes (especially since the Trps are functionally significant). By combining the observed isotropic chemical shifts with the quantum chemically computed shielding surfaces, one obtains for Trp the solutions for c 1, c2 as well as f, y, c 1 results for Val, Leu. These unique solutions remove problems associated with may dipolar or quadrupolar derived geometry restraints, ans when combined with the often more accurate (but multivalued) tensor data should yield very accurate, unique NMR solutions, for f, y, c I, c2. Knowledge of Trp orientations is important for understanding gramicidin action, and the above results (together) with those we are planning to obtain with commercially available 13C glycines and alanines) should together clearly indicate the utility of chemical shifts in structure studies, especially since the chemical shift is, in a sense, the most fundamental NMR property.