SMS 201-995, a very potent analogue of somatostatin. Assignment of the 1H 500 MHz n.m.r. spectra and conformational analysis in aqueous solution.
SMS 201-995, a very potent analogue of somatostatin. Assignment of the 1H 500 MHz n.m.r. spectra and conformational analysis in aqueous solution.
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SMS 201-995，一种非常有效的生长抑素类似物。
DOI：
10.1111/j.1399-3011.1985.tb02217.x
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
H. Loosli
中科院分区：
文献类型：
--
作者：
C. Wynants;G. Van Binst;H. Loosli
本文用核磁共振研究了生长抑素的环状类似物SMS 201-995的构象。在水溶液中在500 MHz下的光谱。通过使用二维相关方法，特别是通过检测长程连接性，以确定芳香族氨基酸和连续残基的α质子之间的长程耦合，进行了序列分析。酰胺质子的温度系数和NH-C α H耦合常数的测量使我们能够得出结论，在水中的分子是相当灵活的，没有证据表明涉及Thr 6的β转结构。涉及两个γ转角构象分别由Cys 2-D-Trp 4和Phe 3-Lys 5氢键稳定的平衡，是负责观察到的Lys 5 γ质子的大的高场位移，并与测得的JNH-C α H耦合常数兼容。
The conformations of a cyclic analogue of somatostatin, SMS 201-995, have been studied by n.m.r. spectroscopy at 500 MHz in aqueous solution. Assignments were made by use of 2D-correlated methods, especially by detecting long-range connectivities in order to identify the aromic amino-acid and long-range couplings between alpha protons of consecutive residues. Measurements of temperature coefficients of amide protons and of NH-C alpha H coupling constants enabled us to conclude that in water the molecule is rather flexible, with no evidence for a beta turn structure involving Thr6. An equilibrium involving two gamma turn conformations stabilized respectively by Cys2-D-Trp4 and Phe3-Lys5 hydrogen bonds, is responsible for the large upfield shift observed for the Lys5 gamma protons and is compatible with the measured JNH-C alpha H coupling constants.