Gathercole L J, Barnard K, Atkins E D
H. H. Wills Physics Laboratory, University of Bristol, UK.
Int J Biol Macromol. 1989 Dec;11(6):335-8. doi: 10.1016/0141-8130(89)90004-4.
A new X-ray diffraction pattern from type IV collagen is described, which can be interpreted on the basis of crystalline and liquid crystalline origins of the reflections. Bovine anterior lens capsules extracted with 1 M NaCl and oriented by extension of 60% under constant load gave medium angle X-ray diffraction patterns showing many of the characteristics typical of liquid crystals. Prominent features, apart from those wide angle features attributable to the collagen triple helix, are (1) a four-point pattern of broad reflections at d-spacing 3.9 nm, and layer line spacing near 5 nm. (2) A broad intense equatorial peak centred at 1.24 nm, indicative of liquid-like lateral molecular associations. (3) A set of five sharp, streaked meridional reflections (previously obscured by the broad peak near 5 nm in unextracted capsules). (4) A further six higher angle reflections of a diffuse, arced and broad appearance on the meridian. The sharp streaked meridional reflections emanate from a long-range periodicity of units 8-9 nm in diameter. These features form a self-consistent system if interpreted on the basis of a staggered liquid crystal-like array of collagen molecules, in which case the first five meridionals and remaining broad reflections, sampled on the meridian, can all be indexed as orders of 21 nm.
本文描述了IV型胶原的一种新的X射线衍射图谱，该图谱可基于反射的晶体和液晶起源进行解释。用1M NaCl提取并在恒定负荷下延伸60%进行取向的牛眼前囊膜给出了中角X射线衍射图谱，显示出许多液晶特有的特征。除了归因于胶原三螺旋的那些广角特征外，突出的特征还有：（1）在d间距3.9nm处有一个四点宽反射图案，层线间距接近5nm。（2） 一个以1.24nm为中心的宽而强的赤道峰，表明存在类似液体的侧向分子缔合。（3） 一组五个尖锐的、有条纹的子午线反射（以前在未提取的囊膜中被5nm附近的宽峰掩盖）。（4） 在子午线上还有另外六个较高角度的反射，呈漫射、弧形且宽。尖锐的有条纹的子午线反射源自直径为8-9nm的单元的长程周期性。如果基于胶原分子的交错液晶样阵列进行解释，这些特征形成一个自洽系统，在这种情况下，子午线上采样的前五个子午线反射和其余宽反射都可以索引为21nm的级次。
