Secondary structure determination of human beta-endorphin by 1H NMR spectroscopy.
Secondary structure determination of human beta-endorphin by 1H NMR spectroscopy.
复制标题
通过 1H NMR 光谱法测定人 β-内啡肽的二级结构。
作者：
Lichtarge,O;Jardetzky,O;Li,CH
Olivier Lichtarge，1 Oleg Jardetzky，*·* 和Choh Hao Li §斯坦福大学磁共振实验室，斯坦福大学，斯坦福大学，加州94305-5055，和分子内分泌学实验室，加州大学，弗朗西斯科，加州94143接收于1987年3月11日;修订后的手册接收于1987年4月16日摘要：人0-内啡肽的NMR谱表明，该肽在水溶液中以无规卷曲形式存在，但在混合溶剂中变为螺旋状。热变性NMR实验表明，在24 ~ 75 ℃范围内，在水中没有热变性转变，而在60%甲醇-40%水混合溶剂中，在相同温度范围内，观察到缓慢的非协同热去折叠。这些发现与圆二色性研究的其他工作者得出的结论一致，即0-内啡肽在水中是无规卷曲，但在混合溶剂中形成50%或更多的螺旋。通过相关光谱（COSY）和核欧弗豪泽效应光谱（NOESY）实验进一步研究了水-甲醇混合溶剂中的肽。这些允许一套完整的分配，并建立两个不同的延伸，其中溶剂诱导形成螺旋：第一个发生在Tyr-1和Thr-12之间，第二个发生在Leu-14和延伸到Lys-28之间。有证据表明，后者被发生在Lys-28和Glu-31之间的转折所限制。这些螺旋在氨基末端的脑啡肽受体结合位点和羧基末端的吗啡受体结合位点形成[Li，C. H. 05.《细胞》（剑桥，马萨诸塞州）31，504-505]，我们的发现表明这两种受体可以特异性地识别α-螺旋。
Olivier Lichtarge, 1 Oleg Jardetzky,*·* and Choh Hao Li § Stanford Magnetic Resonance Laboratory, Stanford University, Stanford, California 94305-5055, and Laboratory of Molecular Endocrinology, University of California, San Francisco, California 94143 Received March 11, 1987; Revised Manuscript Received April 16, 1987 abstract: The NMR spectra of human 0-endorphin indicate that the peptide exists in random-coil form in aqueous solution but becomes helical in mixed solvent. Thermal denaturation NMR experiments show that in water there is no transition between 24 and 75 C, while a slow noncooperativethermal unfolding is observed in a 60% methanol-40% water mixed solvent in the same temperature range. These findings are consistent with circular dichroism studies by other workers concludingthat 0-endorphin is a random coil in water but that it forms 50%-helix or more in mixed solvents. The peptide in the mixed water-methanol solvent was further studied by correlated spectroscopy (COSY) and nuclear Overhauser effect spectroscopy (NOESY) experiments. These allow a complete set of assignments to be made and establish two distinct stretches over which the solvent induces formation of-helices: the first occurs between Tyr-1 and Thr-12 and the second between Leu-14 and extending to Lys-28. There is evidence that the latter is capped by a turn occurring between Lys-28 and Glu-31. These helices form at the enkephalin receptor binding site, which is at the amino terminus, and at the morphine receptorbinding site, located at thecarboxyl terminus [Li, C. H.(1982) Cell (Cambridge, Mass.) 31, 504-505], Our findings suggest that these two receptors may specifically recognize a-helices.