Nevzorov Alexander A
Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
J Magn Reson. 2014 Dec;249:9-15. doi: 10.1016/j.jmr.2014.09.023. Epub 2014 Oct 6.
A new approach for calculating solid-state NMR lineshapes of uniaxially rotating membrane proteins under the magic-angle spinning conditions is presented. The use of stochastic Liouville equation (SLE) allows one to account for both coherent sample rotation and stochastic motional averaging of the spherical dipolar powder patterns by uniaxial diffusion of the spin-bearing molecules. The method is illustrated via simulations of the dipolar powder patterns of rigid samples under the MAS conditions, as well as the recent method of rotational alignment in the presence of both MAS and rotational diffusion under the conditions of dipolar recoupling. It has been found that it is computationally more advantageous to employ direct integration over a spherical grid rather than to use a full angular basis set for the SLE solution. Accuracy estimates for the bond angles measured from the recoupled amide H-N dipolar powder patterns have been obtained at various rotational diffusion coefficients. It has been shown that the rotational alignment method is applicable to membrane proteins approximated as cylinders with radii of approximately 20Å, for which uniaxial rotational diffusion within the bilayer is sufficiently fast and exceeds the rate 2×10s.
提出了一种在魔角旋转条件下计算单轴旋转膜蛋白固态核磁共振线形的新方法。使用随机刘维尔方程（SLE）可以同时考虑样品的相干旋转以及自旋承载分子单轴扩散对球形偶极粉末图案的随机运动平均化。通过模拟MAS条件下刚性样品的偶极粉末图案以及在偶极重耦条件下同时存在MAS和旋转扩散时的旋转取向的最新方法，对该方法进行了说明。已经发现，对于SLE解，在球形网格上进行直接积分在计算上比使用完整的角基组更具优势。在各种旋转扩散系数下，已获得从重耦酰胺H-N偶极粉末图案测量的键角的精度估计。结果表明，旋转取向方法适用于近似为半径约20Å圆柱体的膜蛋白，对于这些膜蛋白，双层内的单轴旋转扩散足够快且超过2×10s的速率。
