Williamson P T F, Bains S, Chung C, Cooke R, Watts A
Laboratorium für Physikalische Chemie, ETH-Hönggerberg, CH-8093 Zurich, Switzerland.
FEBS Lett. 2002 May 8;518(1-3):111-5. doi: 10.1016/s0014-5793(02)02656-x.
A functionally active analogue of neurotensin, neurotensin(8-13), has been observed whilst bound to the agonist-binding site of the rat neurotensin receptor by nuclear magnetic resonance (NMR). Through the application of slow magic angle sample spinning and high-power proton decoupling, sufficient resolution and sensitivity were obtained in the carbon-13 spectrum to allow an assignment of many of the side chain resonances arising from uniformly carbon-13/nitrogen-15-labelled neurotensin(8-13) whilst bound to the neurotensin receptor. Significant perturbations in carbon-13 chemical shift were observed upon the binding of the neurotensin(8-13) to the receptor. Most importantly significant shifts were observed in both the carboxy terminus and tyrosine side chain of the neurotensin(8-13), suggesting that these sites are important in the interaction of the neurotensin with the agonist-binding site on the neurotensin receptor. Conversely, no perturbations were observed for the carbon-13 sites within the guanidinium groups of the arginine side chains, indicating little interaction with the receptor-binding site, or a shielding of the local environment by the surrounding nitrogen atoms. These NMR observations lend further support to previous structure-activity studies, site-directed mutagenesis and modelling studies of the agonist-binding site of the neurotensin receptor, from which the same specific residues for which NMR perturbations were observed are important for neurotensin receptor activation by neurotensin.
通过核磁共振（NMR）观察到，一种具有功能活性的神经降压素类似物，即神经降压素（8-13），在与大鼠神经降压素受体的激动剂结合位点结合时的情况。通过应用慢速魔角样品旋转和高功率质子去耦，在碳-13谱中获得了足够的分辨率和灵敏度，从而能够对来自均匀碳-13/氮-15标记的神经降压素（8-13）与神经降压素受体结合时产生的许多侧链共振进行归属。当神经降压素（8-13）与受体结合时，观察到碳-13化学位移有显著扰动。最重要的是，在神经降压素（8-13）的羧基末端和酪氨酸侧链均观察到显著位移，这表明这些位点在神经降压素与神经降压素受体上的激动剂结合位点的相互作用中很重要。相反，在精氨酸侧链的胍基内的碳-13位点未观察到扰动，这表明与受体结合位点的相互作用很小，或者周围氮原子对局部环境有屏蔽作用。这些NMR观察结果进一步支持了先前关于神经降压素受体激动剂结合位点的结构活性研究、定点诱变和建模研究，从这些研究中观察到NMR扰动的相同特定残基对于神经降压素激活神经降压素受体很重要。
