MACROMOLECULAR STRUCTURE

生物大分子组装的结构和机制 研究了大分子和大分子复合物， 通过高分辨率电子显微镜和计算机图像 处理，但也包括其他信息，如氨基- 酸序列分析 在过去一年中， 主要是（1）冻水化横向薄层分析 松弛和僵硬骨骼肌的切片;（2）配制 纤维受体识别蛋白的分子模型 呼肠孤病毒;和（3）表征发现的规则表面晶格 在两种百日咳杆菌的外膜上。 (1)对冷冻切片图像进行非线性对比度恢复后， 转移纠正空间障碍，并平均，以改善 信噪比，我们观察到的分布 在肌丝晶格的投射单位晶胞内的质量， 两个国家。 进入僵直状态时，质量从 肌球蛋白丝的外围包围肌动蛋白丝。 我们还观察到了影响肌球蛋白丝僵硬的变化， 在没有肌动蛋白的情况下。 (2)加热后从reovirion释放的Sigma-1蛋白纤维 是同源四聚体分子，48 nm长x 5- 9 nm宽。 远侧 杆的一部分是由两个螺旋线圈螺旋绳放置， 肩并肩 这部分之后是一个更广泛的部分， 与第一个（23纳米）相同的长度，但更宽，包含 可见的亚结构，并富含β-折叠构象。 最后，羧基末端形成球状结构域， 受体结合位点存在。 (3)应用广义图像平均技术，我们发现 那个B。百日咳表面网格为长方形， p2对称性 它的单位细胞含有细菌的两个三聚体， 40 K阴离子选择性孔蛋白，在不同的方向。 这些 孔蛋白在结晶状态下是有活性的， 显示出这种结构的这些菌株的生长速率。

The structures and mechanisms of assembly of biological macromolecules and macromolecular complexes are studied, primarily by high resolution electron microscopy and computer image processing, but also incorporating other information such as amino- acid sequence analyses. Over the past year, we have made headway primarily in (1) analysis of frozen-hydrated transverse thin sections of relaxed and rigor skeletal muscle; (2) formulating a molecular model for the fibrous receptor-recognition protein of reovirus; and (3) characterizing the regular surface lattice found in the outer membranes of two strains of Bordetella pertussis. (1) After restoring the cryo-section images for non-linear contrast transfer correcting for spatial disorders, and averaging to improve the signal-to-noise ratio, we have observed the distribution of mass within the projected unit cell of the myofilament lattice in both states. On entering rigor, mass is transferred from the periphery of the myosin filaments to surround the actin filaments. We also observe changes to affect myosin filaments in rigor even in the absence of actin. (2) Sigma-1 protein fibers released from reovirions upon heating are homotetrameric molecules, 48nm long x 5-9nm wide. The distal part of the rod is made up of two coiled-coil helical ropes placed side-by-side. This segment is followed by a wider portion of about the same length as the first (23nm) but which is wider, contains visible substructure, and is rich in beta-sheet conformation. Finally, the carboxy termini form globular domains where the receptor-combining sites reside. (3) Applying generalized image averaging techniques, we have found that the B. pertussis surface lattice is rectangular and observes p2 symmetry. Its unit cell contains two trimers of the bacterium's 40K anion-selective porin, in different orientations. That these porins are active in the crystalline state is implied by the normal growth rate of these strains that exhibit this structure.