Shenderovich M D, Sekatsis I P, Liepin'sh E E, Nikiforovich G V, Papsuevich O S
Bioorg Khim. 1985 Sep;11(9):1180-91.
2D 1H-NMR spectra of des-Gly9-[Arg8]vasopressin in dimethylsulfoxide have been taken and the 1H resonances have been assigned. The coupling constants and amide proton temperature coefficients (delta delta/delta T) have been measured and the NOE cross-peaks in the NOESY spectrum have been analyzed. The most essential information on the spatial structure of des-Gly9-[Arg8]vasopressin is extracted from the low delta delta/delta T value for Asn5 amide proton and from the NOE between the Cys1 and Cys6 alpha-protons. A diminished accessibility of the Asn5 NH proton for the solvent is ascribed to the presence of a beta-turn in the fragment 2-5. The distance between the Cys1 and Cys6 C alpha H protons seems to be less than 4 A. These constraints were taken into account in the conformational analysis of the title peptide. The derived set of the low-energy backbone conformations was analyzed against the background of the all available NMR data. The most probable conformation of the cyclic moiety in des-Gly9-[Arg8]vasopressin was found to be the type III beta-turn. The corner positions are occupied by the residues 3, 4, while the residues 1-2 and 5-6 are at the extended sites. Some NMR data indicate that this structure is in a dynamic equilibrium with other minor conformers.
已获取去甘氨酸9 - [精氨酸8]加压素在二甲基亚砜中的二维¹H - NMR谱，并对¹H共振进行了归属。测量了耦合常数和酰胺质子温度系数（δδ/δT），并分析了NOESY谱中的NOE交叉峰。关于去甘氨酸9 - [精氨酸8]加压素空间结构的最重要信息是从Asn5酰胺质子的低δδ/δT值以及Cys1和Cys6 α - 质子之间的NOE中提取的。Asn5 NH质子对溶剂的可及性降低归因于片段2 - 5中存在β - 转角。Cys1和Cys6 CαH质子之间的距离似乎小于4埃。在标题肽的构象分析中考虑了这些限制。根据所有可用的NMR数据背景，分析了导出的低能量主链构象集。发现去甘氨酸9 - [精氨酸8]加压素中环状部分最可能的构象是III型β - 转角。转角位置由残基3、4占据，而残基1 - 2和5 - 6处于伸展位点。一些NMR数据表明该结构与其他次要构象异构体处于动态平衡。
