Saulitis Iu B, Liepin'sh E E, Sekatsis I P, Mutulis F K, Chipens G I
Bioorg Khim. 1986 Apr;12(4):437-47.
The role of charged groups of the nonapeptide bradykinin in stabilization of its spatial structure in dimethyl sulfoxide solution was investigated. The signal assignment in the 1H-NMR spectra was achieved by means of two dimensional correlated spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy (NOESY). The changes in the NH and C alpha H proton chemical shifts of the Arg1 and Arg9 residues, variations both in temperature coefficients of chemical shifts of NH-resonances and coupling constants, as well as the appearance of additional NOE cross-peaks in NOESY spectra for d alpha N and d beta N 1H-1H distances were revealed by comparing the NMR spectra for two states--with the protonated C-terminal carboxyl group and deprotonated one. The experimental results are in agreement with the assumption that the conformation of the peptide in (CD3)2SO is stabilized by electrostatic interaction between the oppositely charged N- and C-terminal groups. The conformation with deprotonated alpha-carboxyl group is characterized by two beta-turns in the sequences Pro2-Pro-Gly-Phe5 and Ser6-Pro-Phe-Arg9.
研究了九肽缓激肽的带电基团在二甲基亚砜溶液中对其空间结构稳定性的作用。通过二维相关光谱（COSY）和核Overhauser增强光谱（NOESY）实现了1H-NMR谱中的信号归属。通过比较质子化C末端羧基和去质子化C末端羧基两种状态的NMR谱，揭示了Arg1和Arg9残基的NH和CαH质子化学位移的变化、NH共振化学位移的温度系数和耦合常数的变化，以及在NOESY谱中dαN和dβN 1H-1H距离出现的额外NOE交叉峰。实验结果与以下假设一致：肽在（CD3）2SO中的构象通过带相反电荷的N末端和C末端基团之间的静电相互作用得以稳定。去质子化α-羧基的构象在序列Pro2-Pro-Gly-Phe5和Ser6-Pro-Phe-Arg9中具有两个β-转角。
