Wess T J, Hammersley A P, Wess L, Miller A
Department of Biological and Molecular Sciences, University of Stirling, UK.
J Mol Biol. 1998 Jan 16;275(2):255-67. doi: 10.1006/jmbi.1997.1449.
X-ray diffraction of rat tail tendon shows that type I collagen fibrils contain regions of three-dimensional crystalline arrays; where molecular packing is speculated to be by a staggered sheet or microfibril arrangement. The X-ray diffraction pattern also contains a significant amount of diffuse scatter indicative of static and thermal disorder in fibrils. Removal of the diffuse scatter from the equatorial region of X-ray diffraction patterns obtained using synchrotron radiation allowed the Bragg intensities to be viewed on a flat background. Indexing of Bragg peak intensity on the 10, -10, 0 -1, 01, -11 and 1-1 row-lines of the triclinic unit cell have been used here to test possible sheet and microfibril packing arrangements. The relative translation of molecular segments in the gap and overlap regions as well as the telopeptide orientation have been investigated. A global search through combinations of molecular packing and molecular translation revealed that the sheet-type conformations cannot account for the observed low-angle off-meridional Bragg peak intensity distribution. A superior fit is obtained with D-staggered left-handed microfibril structures. The orientation of the telopeptides may indicate that there are interconnections between microfibrils that may explain the difficulty in isolating individual microfibrillar structures.
大鼠尾腱的X射线衍射表明，I型胶原纤维含有三维晶体阵列区域；据推测，分子堆积是通过交错片层或微纤维排列实现的。X射线衍射图还包含大量漫散射，表明纤维中存在静态和热无序。去除使用同步辐射获得的X射线衍射图赤道区域的漫散射，使得布拉格强度能够在平坦背景上观察到。这里利用三斜晶胞的10、-10、0 -1、01、-11和1-1行线上的布拉格峰强度进行索引，以测试可能的片层和微纤维堆积排列。已经研究了间隙和重叠区域中分子片段的相对平移以及端肽取向。通过分子堆积和分子平移组合的全局搜索发现，片层型构象无法解释观察到的低角度离子午线布拉格峰强度分布。D型交错左旋微纤维结构能获得更好的拟合。端肽的取向可能表明微纤维之间存在相互连接，这可能解释了分离单个微纤维结构的困难。
