RESIDUAL DIPOLAR COUPLINGS FOR REFINEMENT OF PROTEIN STRUCTURES

近年来，人们发展了核磁共振方法来准确地测量 一个键的1JNH耦合常数。表观1JNH耦合常数 是标量耦合和剩余偶极耦合之和。 由于剩余偶极子耦合成正比于 静电场和标量耦合是恒定的 场强、剩余偶极耦合可以从以下位置测量 表观1JNH耦合常数的场依赖性。残渣 偶极耦合是由于分子的偏序引起的。 磁场与N-H键之间的夹角有关 矢量和磁化率张量。因此，它一直是 建议将剩余偶极耦合用作附加的 蛋白质结构测定中的制约因素。我们建议 测量几种蛋白质的剩余偶极偶联 确定这是否为结构中的有用约束 蛋白质的测定。尽管我们可以接触到500和600 MHZ核磁共振光谱仪用于测量单键耦合，我们需要 在更高的磁场下测量这些耦合以可靠地推导出 从观测到的场的依赖关系得到的残余偶极耦合 1JNH耦合常数。

Recently, NMR methods have been developed to accurately measure one bond 1JNH coupling constants. The apparent 1JNH coupling constant is the sum of the scalar coupling and the residual dipolar coupling. Since the residual dipolar coupling is proportional to the square of the static field and the scalar coupling is constant as a function of field strength, residual dipolar couplings can be measured from the field dependnece of the apparent 1JNH coupling constants. Residual dipolar couplings occur due to the partial ordering of a molecule in the magnetic field and are related to the angle between the N-H bond vector and the magnetic susceptibility tensor. Thus, it has been suggested that residual dipolar couplings could be used as additional constraints in the structure determination of proteins. We propose to measure the residual dipolar couplings for several proteins to determine whether this is a useful constraint in the structure determination of proteins. Although we have access to a 500 and 600 MHz NMR spectrometer for measuring one bond couplings, we need to measure these couplings at higher fields to reliably derive the residual dipolar couplings from the field dependence of the observed 1JNH coupling constants.