Identification and localization of bound internal water in the solution structure of interleukin 1 beta by heteronuclear three-dimensional 1H rotating-frame Overhauser 15N-1H multiple quantum coherence NMR spectroscopy.
Identification and localization of bound internal water in the solution structure of interleukin 1 beta by heteronuclear three-dimensional 1H rotating-frame Overhauser 15N-1H multiple quantum coherence NMR spectroscopy.
复制标题
利用异核三维 1H 旋转框架 Overhauser 15N-1H 多量子相干核磁共振波谱鉴定和定位白细胞介素 1β 溶液结构中的内部结合水。
作者：
G. Clore;A. Bax;P. Wingfield;A. Gronenborn
利用三维1H重叠框架Overhauser 1H-15 N多量子相干光谱（ROESY-HMQC）研究了白细胞介素1 β（IL 1 β）溶液结构中结合水分子的存在和位置。在该实验中，NH质子和结合水之间的间隔小于或等于3.5 A的通过空间的双折射框架Overhauser（ROE）相互作用与化学交换效应明显不同，因为这两个过程的交叉峰具有相反的符号。根据直接键合的氮原子的15 N化学位移，通过将光谱扩展到第三维，可以简单地识别NH质子和水之间的ROE。通过这种方式，在除了极少数有限的情况之外的所有情况下，完全避免了在诸如白细胞介素1 β的大蛋白质的2D 1H-1H ROESY光谱中阻止NH质子和水之间的ROE峰的解释、鉴定和分配的问题，即广泛的NH化学位移简并性和被强得多的化学交换峰遮蔽的ROE峰。我们证明了15 NH质子的存在，接近结合水分子。从白细胞介素1 β的晶体结构的检查[Finzel，B. C.的方法，克兰西湖L.，Holland，D. R.，Muchmore，S. W.，Watenpaugh，K. D、& Einspahr，H. M.等人（1989）J. Mol. Biol.209，779-791]，结果可归因于11个水分子，其参与桥接与骨架酰胺和羰基的氢键相互作用，所述骨架酰胺和羰基稳定白细胞介素1 β的3重假对称拓扑结构，因此构成溶液中蛋白质结构的组成部分。
The presence and location of bound internal water molecules in the solution structure of interleukin 1 beta have been investigated by means of three-dimensional 1H rotating-frame Overhauser 1H-15N multiple quantum coherence spectroscopy (ROESY-HMQC). In this experiment through-space rotating-frame Overhauser (ROE) interactions between NH protons and bound water separated by less than or equal to 3.5 A are clearly distinguished from chemical exchange effects, as the cross-peaks for these two processes are of opposite sign. The identification of ROEs between NH protons and water is rendered simple by spreading out the spectrum into a third dimension according to the 15N chemical shift of the directly bonded nitrogen atoms. By this means, the problems that prevent, in all but a very few limited cases, the interpretation, identification, and assignment of ROE peaks between NH protons and water in a 2D 1H-1H ROESY spectrum of a large protein such as interleukin 1 beta, namely, extensive NH chemical shift degeneracy and ROE peaks obscured by much stronger chemical exchange peaks, are completely circumvented. We demonstrate the existence of 15 NH protons that are close to bound water molecules. From an examination of the crystal structure of interleukin 1 beta [Finzel, B. C., Clancy, L. L., Holland, D. R., Muchmore, S. W., Watenpaugh, K. D., & Einspahr, H. M. (1989) J. Mol. Biol. 209, 779-791], the results can be attributed to 11 water molecules that are involved in interactions bridging hydrogen-bonding interactions with backbone amide and carbonyl groups which stabilize the 3-fold pseudosymmetric topology of interleukin 1 beta and thus constitute an integral part of the protein structure in solution.