Ludvigsen S, Poulsen F M
Carlsberg Laboratorium, Kemisk Afdeling, Copenhagen, Denmark.
Biochemistry. 1992 Sep 22;31(37):8783-9. doi: 10.1021/bi00152a014.
The solution structure of a 125-residue basic protein, barwin, has been determined using 1H nuclear magnetic resonance spectroscopy. This protein is closely related to domains in proteins encoded by wound-induced genes in plants. Analysis of the 1H nuclear Overhauser spectrum revealed the assignment of more than 1400 nuclear Overhauser effects. Twenty structures were calculated based on 676 nontrivial distance restraints, 152 torsion angle restraints (92 phi, 56 chi 1, and 4 omega for proline), and stereospecific assignments of 38 chiral centers, using distance geometry, simulated annealing, and restrained energy minimization. None of the distance restraints was violated by more than 0.5 A in any of the 20 structures, and none of the torsion angle restraints was violated by more than 1 degree in any of the structures. The RMS difference between the calculated and target interproton distance restraints is 0.033 A, and the average atomic RMS differences between the 20 structures and their geometric average are 1.23 A for backbone atoms and 1.73 A for all heavy atoms. The dominating structural feature of the protein is a well-defined four-stranded antiparallel beta-sheet, two parallel beta-sheets packed antiparallel to each other and four short alpha-helices. The binding site of barwin to the tetramer N-acetylglucosamine has been qualitatively investigated, and the dissociation constant of the complex has been determined using one-dimensional 1H nuclear magnetic resonance spectroscopy.
已使用1H核磁共振光谱法确定了一种由125个氨基酸残基组成的碱性蛋白barwin的溶液结构。该蛋白与植物伤口诱导基因编码的蛋白结构域密切相关。对1H核Overhauser谱的分析揭示了1400多个核Overhauser效应的归属。基于676个非平凡距离限制、152个扭转角限制（92个phi角、56个chi 1角和4个脯氨酸的omega角）以及38个手性中心的立体专一性归属，采用距离几何法、模拟退火法和受限能量最小化法计算了20种结构。在这20种结构中的任何一种中，距离限制的违反均未超过0.5 Å，扭转角限制的违反在任何结构中均未超过1°。计算得到的质子间距离限制与目标值之间的RMS差异为0.033 Å，20种结构与其几何平均值之间的平均原子RMS差异对于主链原子为1.23 Å，对于所有重原子为1.73 Å。该蛋白的主要结构特征是一个明确的四链反平行β折叠、两个相互反平行堆积的平行β折叠和四个短α螺旋。已对barwin与四聚体N-乙酰葡糖胺的结合位点进行了定性研究，并使用一维1H核磁共振光谱法测定了复合物的解离常数。
