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X射线衍射法是测定蛋白质晶体结构的有效方法。晶体的培养是结构分析的第一步,生物大分子晶体的培养是比较困难的,特别是在量少的情况下,要生长出X射线衍射法适用的单晶体尤为困难。作为X射线结构分析用的晶体与单纯作为纯化手段培养的晶体不同,它必须符合下述三个条件: 1.晶体要足够大晶体越大,X射线衍射强度也越强。像蛋白质这样大的分子量,构成晶体的单胞也大。在测定晶体单胞大小和对称性的初步结构分析时,晶体每边最小要50微米以上。进一步结构分析时,晶体要求每边为300—500微米。
X-ray diffraction method is an effective method to determine the crystal structure of protein. The cultivation of crystals is the first step in the structural analysis. The cultivation of biological macromolecules crystals is more difficult. Especially in the case of small amount, it is particularly difficult to grow single crystals suitable for X-ray diffraction. The crystal used for X-ray structure analysis must be different from the pure crystal culture method as follows: 1. The crystal should be large enough. The larger the crystal, the stronger the X-ray diffraction intensity. Like protein, such a large molecular weight, the crystal unit cell is also large. In determining the initial structure of the unit cell size and symmetry of the crystal, the minimum crystal size must be 50 microns or more. For further structural analysis, the crystal requires 300-500 microns on each side.