Levian-Teitelbaum D, Kolodny N, Chorev M, Selinger Z, Gilon C
Biopolymers. 1989 Jan;28(1):51-64. doi: 10.1002/bip.360280108.
Proton nmr parameters are reported for DMSO-d6 solutions of two receptor-selective substance P analogues: Ac[Arg6,Pro9]SP6-11, which is selective for the NK-1 (SP-P) receptor and [pGlu6,N-MePhe8]SP6-11, which selectively activates the NK-3 (SP-N) receptor. Full peak assignments of both analogues were obtained by COSY experiments. The chemical shifts, coupling constants, and temperature coefficients of amide proton chemical shifts as well as NOESY effects and calculated side-chain rotamer populations of Phe side chains are reported for both peptides. Analysis of coupling constants and temperature coefficients together with the nuclear Overhauser enhancement spectroscopy effects suggest that Ac[Arg6,Pro9]SP6-11 has a trans configuration about the Phe8-Pro9 amide bond and the preferred conformation of this analogue has a type I beta-turn. The nmr data for [pGlu6,N-MePhe8]SP6-11 suggest that this peptide exists as a mixture of cis-trans isomers in which the cis isomer can preferably adopt a type VI beta-turn conformation, and the trans isomer can adopt a gamma-turn conformation. There are indications that the two last turns are stabilized by a hydrogen bond between the syn carboxamide proton and the pGlu ring carbonyl.
报道了两种受体选择性P物质类似物在氘代二甲亚砜（DMSO-d6）溶液中的质子核磁共振（NMR）参数：对NK-1（SP-P）受体具有选择性的Ac[Arg6,Pro9]SP6-11，以及选择性激活NK-3（SP-N）受体的[pGlu6,N-MePhe8]SP6-11。通过化学位移相关谱（COSY）实验获得了两种类似物的完整峰归属。报道了两种肽的化学位移、耦合常数、酰胺质子化学位移的温度系数以及核Overhauser效应光谱（NOESY）效应和苯丙氨酸（Phe）侧链的计算侧链旋转异构体群体。对耦合常数和温度系数以及核Overhauser增强光谱效应的分析表明，Ac[Arg6,Pro9]SP6-11在Phe8-Pro9酰胺键周围具有反式构型，且该类似物的优选构象具有I型β-转角。[pGlu6,N-MePhe8]SP6-11的核磁共振数据表明，该肽以顺反异构体混合物的形式存在，其中顺式异构体可优选采用VI型β-转角构象，反式异构体可采用γ-转角构象。有迹象表明，最后两个转角通过顺式羧酰胺质子与焦谷氨酸（pGlu）环羰基之间的氢键得以稳定。
