Fejzo J, Krezel A M, Westler W M, Macura S, Markley J L
Biochemistry Department, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706.
Biochemistry. 1991 Apr 23;30(16):3807-11. doi: 10.1021/bi00230a001.
The effect of internal motion on the quality of a protein structure derived from nuclear magnetic resonance (NMR) cross relaxation has been investigated experimentally. Internal rotation of the tyrosine-31 ring of turkey ovomucoid third domain was found to mediate magnetization transfer; the effect led to underestimation of proton-proton distances in its immediate neighborhood. Experimental methods that distinguish pure cross relaxation from chemical exchange mediated cross relaxation were used to separate true distances from distorted ones. Uncorrected and corrected sets of distances, where the corrections took internal motion into account, each were used as input to a distance geometry program for structural modeling. Each set of distances yielded a family of similar (converged) structures. The two families of structures differed considerably (2 A) in the region of tyrosine-31. In addition, differences as large as 1 A were observed at other positions throughout the structure. These results emphasize the importance of analyzing the effects of internal motions in order to obtain more accurate NMR solution structures.
已通过实验研究了内部运动对源自核磁共振（NMR）交叉弛豫的蛋白质结构质量的影响。发现火鸡卵类粘蛋白第三结构域酪氨酸-31环的内部旋转介导了磁化转移；这种效应导致其紧邻区域内质子-质子距离的低估。使用将纯交叉弛豫与化学交换介导的交叉弛豫区分开来的实验方法，将真实距离与失真距离分开。未校正的距离集和考虑了内部运动进行校正的距离集，分别用作距离几何程序进行结构建模的输入。每组距离都产生了一族相似（收敛）的结构。这两族结构在酪氨酸-31区域有很大差异（2埃）。此外，在整个结构的其他位置也观察到了高达1埃的差异。这些结果强调了分析内部运动的影响以获得更准确的NMR溶液结构的重要性。
