Iwadate M, Asakura T, Dubovskii P V, Yamada H, Akasaka K, Williamson M P
Department of Biotechnology, Tokyo University of Agriculture and Technology, Japan.
J Biomol NMR. 2001 Feb;19(2):115-24. doi: 10.1023/a:1008392327013.
A novel method is described, which uses changes in NMR chemical shifts to characterise the structural change in a protein with pressure. Melittin in methanol is a small alpha-helical protein, and its chemical shifts change linearly and reversibly with pressure between 1 and 2000 bar. An improved relationship between structure and HN shift has been calculated, and used to drive a molecular dynamics-based calculation of the change in structure. With pressure, the helix is compressed, with the H-O distance of the NH-O=C hydrogen bonds decreased by 0.021 +/- 0.039 A, leading to an overall compression along the entire helix of about 0.4 A, corresponding to a static compressibility of 6 x 10(-6) bar(-1). The backbone dihedral angles phi and psi are altered by no more than +/- 3 degrees for most residues with a negative correlation coefficient of -0.85 between phi(i) and psi(i - 1), indicating that the local conformation alters to maintain hydrogen bonds in good geometries. The method is shown to be capable of calculating structural change with high precision, and the results agree with structural changes determined using other methodologies.
本文描述了一种新方法，该方法利用核磁共振化学位移的变化来表征蛋白质在压力作用下的结构变化。甲醇中的蜂毒肽是一种小的α-螺旋蛋白，其化学位移在1至2000巴的压力范围内随压力呈线性且可逆变化。已计算出结构与HN位移之间的改进关系，并用于驱动基于分子动力学的结构变化计算。随着压力增加，螺旋被压缩，NH-O=C氢键的H-O距离减小了0.021±0.039 Å，导致整个螺旋沿轴向整体压缩约0.4 Å，对应静态压缩率为6×10⁻⁶ bar⁻¹。大多数残基的主链二面角φ和ψ变化不超过±3°，φ(i)与ψ(i - 1)之间的负相关系数为-0.85，这表明局部构象发生改变以保持氢键处于良好的几何构型。结果表明该方法能够高精度地计算结构变化，且计算结果与使用其他方法确定的结构变化一致。
