Deduction of the single‐myosin‐filament transforms from partially sampled layer lines in the X‐ray diffraction pattern from vertebrate striated muscle
Deduction of the single‐myosin‐filament transforms from partially sampled layer lines in the X‐ray diffraction pattern from vertebrate striated muscle
复制标题
从脊椎动物横纹肌 X 射线衍射图中部分采样的层线推论单肌球蛋白丝变换
DOI：
10.1107/s0021889811006455
复制
发表时间：
2011
影响因子：
6.1
通讯作者：
K. Wakabayashi
中科院分区：
文献类型：
--
作者：
K. Oshima;Y. Sugimoto;K. Wakabayashi
利用圆柱平均差分帕特森函数[ΔQ(r, z)]，研究人员开发了一种新的方法，用于校正高级脊椎动物横纹肌x射线衍射图中厚（肌凝蛋白）-基于丝的层线上的统计超晶格形式的六边形丝阵列造成的部分采样效应。该方法包括在观察到的层线强度计算的ΔQ（r, z）图上切断出现在~ 32 nm以外径向区域的丝间矢量峰，然后通过截断的ΔQ（r, z）的傅里叶反变换推导出单肌凝蛋白-丝变换。采用单肌球蛋白-细丝模型和一个超晶格单元胞的六边形细丝阵列模型对截断方法的准确性进行了测试。六角形细丝阵列模型的截短ΔQ（r, z）计算得到的层线强度几乎没有采样峰，除了接近子午线的强度外，层线与单细丝模型的层线强度基本一致。一些残留的差异是由最邻近的细丝之间面对面的交叉桥向量引起的，它们对应于截断ΔQ（r, z）地图中交叉桥向量总数的~ 27.5%，但面对面的交叉桥向量主要贡献了靠近子午线的强度。其残余的离子午层线强度成分对肌肉静息状态下肌球蛋白十字桥最佳方位取向的搜索没有显著影响。
A novel method to correct a partial sampling effect, due to the hexagonal filament array of a statistical superlattice form, on the thick (myosin)-filament-based layer lines in X-ray diffraction patterns from higher-vertebrate striated muscle has been developed using the cylindrically averaged difference Patterson function [ΔQ(r, z)]. The method involves cutting off the inter-filament vector peaks that appear in the radial region beyond ∼32 nm on the ΔQ(r, z) map calculated from the observed layer-line intensities, and then deducing the single-myosin-filament transforms by inverse Fourier transformation of the truncated ΔQ(r, z). The accuracy of the cut-off method was tested using a single-myosin-filament model and a hexagonal filament-array model with a size of one superlattice unit cell. The layer-line intensities calculated from the truncated ΔQ(r, z) of the hexagonal filament-array model showed few sampling peaks, the layer lines being effectively coincident with those from the single-filament model except for the intensities close to the meridian. Some residual differences were caused by the face-to-face inter-crossbridge vectors between closest neighboring filaments, which correspond to ∼27.5% of the total number of crossbridge vectors in the truncated ΔQ(r, z) map, but the face-to-face inter-crossbridge vectors contributed mainly to the intensities close to the meridian. Their remnant off-meridional layer-line intensity components did not significantly affect a search for the optimum azimuthal orientation of myosin crossbridges in the resting state of muscle.