Pellegrini M, Mammi S, Gobbo M, Rocchi R, Peggion E
University of Padova, Department of Organic Chemistry, Italy.
Biopolymers. 1995 Oct;36(4):461-72. doi: 10.1002/bip.360360409.
The conformation of the head-to-tail cyclic analogue of bradykinin in DMSO was investigated by nmr. Three sets of resonances were detected and fully assigned. These were attributed to the presence of three stable conformers, two of which were exchanging on the nmr time scale. A fourth, incomplete set of resonances was detected but not assigned. The three major conformers differ in the conformation at the three X-Pro bonds present. From nuclear Overhauser effect spectroscopy (NOESY) spectra, three sets of interproton distances were derived and used in NOE-restrained distance geometry calculations. The resulting structures were refined by energy minimization to yield families of structures. Conformer I is characterized by the presence of two type VIb beta-turns between Arg1 and Gly4 and between Phe5 and Phe8. The first beta-turn is present also in conformer II, while an inverse gamma-turn bridging Pro3 is the most pronounced structural feature of conformer III.
通过核磁共振研究了缓激肽头对尾环类似物在二甲基亚砜中的构象。检测到三组共振信号并进行了完全归属。这些归因于三种稳定构象体的存在，其中两种在核磁共振时间尺度上发生交换。检测到第四组不完整的共振信号但未进行归属。三种主要构象体在存在的三个X-脯氨酸键处的构象不同。从核Overhauser效应光谱（NOESY）谱中，导出了三组质子间距离，并用于NOE约束距离几何计算。通过能量最小化对所得结构进行优化，得到结构族。构象体I的特征是在精氨酸1和甘氨酸4之间以及苯丙氨酸5和苯丙氨酸8之间存在两个VIb型β-转角。第一个β-转角也存在于构象体II中，而连接脯氨酸3的反向γ-转角是构象体III最显著的结构特征。
