牛脊髓神经丝的体外组装与结构

利用差速离心法从牛脊髓中分离神经丝 ,在电镜下观察了其形态 ;应用扫描隧道显微镜 (STM)研究了它的结构 ,发现神经丝具有长短 2种侧臂 ,二者相间排列 ,相邻长侧臂或相邻短侧臂的间距都是 2 0～ 2 2nm ;由此推测神经丝内部存在 3 /4分子交错 ;还研究了神经丝蛋白的体外组装 ,以胶体金标记的方法证明 ,中等分子量与高分子量的神经丝蛋白 ,都能同低分子量的神经丝蛋白共同装配成 10nm的纤维 ;同时发现 ,中等分子量与高分子量的神经丝蛋白能够组装成一种较细的纤维 ,不同于中间纤维 .     

天然纤维素超显微结构的扫描隧道显微镜研究

用扫描隧道显微镜（ＳＴＭ）对天然纤维素脱脂棉的超显微结构进行了研究,结果表明用ＳＴＭ可直接观察到脱脂棉的微纤丝和基原纤丝。另外,还直接观察到了脱脂棉中纤维素分子的结晶区和非结晶区以及分叉状结构,从而表明棉花纤维素是一种结晶不完全的多聚物。     

A new model of phycobilisome in Spirulina platensis

Phycobilisomes (PBS) were isolated from blue-green alga Spirulina platensis. Scanning tunneling microscope was used to investigate the three-dimensional structure of PBS deposited on freshly cleaved highly oriented py-rolytic graphite (HOPG) in ambient condition at room temperature. The results showed that the rods of PBS radiated from the core to different directions in the space other than arrayed in one plane, which was different from the typical hemi-discoidal model structure. The diameter of PBS was up to 70 nm, and the rod was approximately 50 nm in length. Similar results were observed in Langmuir-Blodgett (LB) film of PBS. The dissociated PBS could reaggregate into rod-like structures and easily form two-dimensional membrane while being absorbed on HOPG, however, no intact PBS was observed. The filling-space model structure of PBS in Spirulina platensis with STM from three-dimensional real space at nanometer scale was found, which showed that this new structural model of PBS surely exists in blue     

钝顶螺旋藻中一种新的模型藻胆体

以钝顶螺旋藻为材料 ,分离得到完整的藻胆体 ,然后用扫描隧道显微镜(STM)对其结构进行研究 .结果表明钝顶螺旋藻藻胆体的结构与传统的半圆盘状结构模型不同 ,藻胆体的杆不是排列在同一平面内 ,而是呈放射状向空间的各个方向伸展 ,藻胆体的直径为 70nm左右 ,杆的长度为 5 0nm左右 ,并且可清楚地观察到藻胆体的杆中圆盘状的藻胆蛋白面对面的聚集在一起 .从藻胆体LB膜的STM图像中也观察到了相同的结果 .藻胆体解离之后 ,STM图像中没有完整藻胆体的结构特征 ,进一步证实前面得到的是完整藻胆体的STM图像 .Chang等人用计算机模拟方法构建了这种放射状结构的藻胆体的理论模型 ,首次用扫描隧道显微镜从三维实空间直接观察到钝顶螺旋藻中这种结构模型的藻胆体的存在 ,并对这种放射状模型的藻胆体的功能进行了讨论 .     

Assembly and structure of neurofllaments isolated from bovine spinal cord

Neurofilaments (NFs) are neuron-specific intermediate filaments. The NFs were isolated from bovine spinal cord by differential centrifugation. The NFs were detected with electron microscopy and scanning tunneling microscopy (STM). Under STM, two kinds of sidearm of NFs were revealed: one was short, the other was long. They were arrayed along the 10-nm width core filaments one by one. The intervals between two adjacent long sidearms or two short sidearms were 20—22 nm, while those between two adjacent long and short sidearms were 10—11 nm. It was proposed that the rod domain of NF triplet prnteins was 3/4-staggered. The assembly properties of NF triplet proteins were also studied. Immuno-colloidal-gold labeling assay showed that NF-M and NF-H are able to co-assemble into long filaments with NF-L. NF-M and NF-H can also co-constitute into winding filaments.