Dorset D L, Massalski A K, Rosenbusch J P
Electron Diffraction Department, Medical Foundation of Buffalo, Inc., NY 14203.
Proc Natl Acad Sci U S A. 1989 Aug;86(16):6143-7. doi: 10.1073/pnas.86.16.6143.
A hexagonal polymorph (a = 79 A) of OmpF matrix porin from Escherichia coli spontaneously transforms to a rectangular form (a = 79 A, b = 137 A) after several months' storage in the refrigerator. Nucleation of this second polymorph is first disclosed by diffuse streaks in electron diffraction patterns or in computer-generated Fourier transforms of electron microscope images. With time, this streaking is resolved as an apparent superlattice, and eventually domains of orthorhombic polymorph are detected in the parent hexagonal lattice that can be oriented in either of three directions, depending on the polarity of the orthorhombic crystal growth. Models for this phenomenon based on protein trimer rotation successfully explain the progress of the phase transition and, if protein-protein interactions are the most important interactions between adjacent trimers in the lipid matrix, the transition is quite similar to what occurs with molecular crystals.
来自大肠杆菌的OmpF基质孔蛋白的一种六边形多晶型物（a = 79 Å）在冰箱中储存几个月后会自发转变为矩形形式（a = 79 Å，b = 137 Å）。这种第二种多晶型物的成核首先通过电子衍射图中的漫散条纹或电子显微镜图像的计算机生成傅里叶变换揭示。随着时间的推移，这种条纹解析为明显的超晶格，最终在母体六边形晶格中检测到正交多晶型物的畴，其可以沿三个方向中的任何一个方向取向，这取决于正交晶体生长的极性。基于蛋白质三聚体旋转的这种现象的模型成功地解释了相变的过程，并且如果蛋白质 - 蛋白质相互作用是脂质基质中相邻三聚体之间最重要的相互作用，那么这种转变与分子晶体中发生的情况非常相似。
