Anderson J P, Cappello J, Martin D C
Macromolecular Science and Engineering Center, College of Engineering, University of Michigan, Ann Arbor 48109-2136.
Biopolymers. 1994 Aug;34(8):1049-58. doi: 10.1002/bip.360340808.
The morphology and primary crystal structure of SLPF, a protein polymer produced by genetically engineered Escherichia coli bacteria, were characterized. SLPF is a segmented copolymer consisting of amino acid sequence blocks modeled on the crystalline segments of silk fibroin and the cell attachment domain of human fibronectin. Wide angle x-ray scattering (WAXS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and molecular simulations were used to analyze the primary crystal structure of SLPF. TEM experiments conducted on SLPF droplets cast from formic acid on amorphous carbon film demonstrated that these protein films have a microstructure formed of woven sheaves. The sheaves are composed of well-defined whisker crystallites. The width of the whiskers, 11.8 +/- 2.2 nm, may be correlated to the length of the silk-like segment in SLPF as predicted by molecular simulations. WAXS data, TEM images, SAED, patterns, molecular simulations, and theoretical diffraction patterns all were consistent with the crankshaft model proposed for Silk I by Lotz and Keith.
对通过基因工程大肠杆菌产生的蛋白质聚合物SLPF的形态和初级晶体结构进行了表征。SLPF是一种嵌段共聚物，由基于丝素蛋白的结晶片段和人纤连蛋白的细胞附着结构域建模的氨基酸序列块组成。使用广角X射线散射（WAXS）、透射电子显微镜（TEM）、选区电子衍射（SAED）和分子模拟来分析SLPF的初级晶体结构。对从甲酸浇铸在非晶碳膜上的SLPF液滴进行的TEM实验表明，这些蛋白质膜具有由编织 sheaves 形成的微观结构。这些 sheaves 由明确的晶须微晶组成。晶须的宽度为11.8 +/- 2.2 nm，可能与分子模拟预测的SLPF中丝状段的长度相关。WAXS数据、TEM图像、SAED图案、分子模拟和理论衍射图案均与Lotz和Keith为丝I提出的曲轴模型一致。
