Abstract:

Under a suitable condition of crystallization, dark brown rhombohedron crystals (the lengths of the longest two diagonals were 0.25 and 0.12 mm, respectively) could be obtained from nitrogenase CrFe protein purified from a mutant UW3 of Azotobacter vinelandii Lipmann grown in Cr containing but NH3 free medium. The possibility of crystallization, as well as the number, size and quality of crystals obviously depended on the concentrations of PEG 8000, MgCl2, NaCl, Tris and Hepes buffer, and methods of crystallization. The optimum concentrations of the chemicals for crystallization of CrFe protein were slightly different from those for crystallization of MnFe protein from UW3 grown in Mn and ΔnifZ MoFe protein from a nifZ deleted strain of A. vinelandii. The crystal seemed to be formed from CrFe protein.

固氮酶铬铁蛋白的晶体生长

张华峰¹  王耀萍²  吕玉兵¹  赵颖¹  代小虎²  董志刚¹  黄巨富^1*

(1. 中国科学院植物研究所,北京,100093; 2.中国科学院生物物理研究所,北京,100101)

在合适的结晶条件下,从含Cr无氨培养基中生长的固氮菌(Azotobacter vinelandii Lipmann)突变种UW3中纯化出的CrFe蛋白可从溶液中析出深棕色斜四棱柱晶体,晶体最大的两条对角线长度分别可达0.25 mm和0.12 mm.PEG 8000、MgCl2、NaCl、Tris 和Hepes 缓冲液的浓度及结晶方法等对该蛋白的出晶率、晶核数目、晶体大小和质量都有明显影响.CrFe蛋白结晶所需的上述化合物的最适浓度与在Mn中生长的固氮菌突变种UW3的MnFe蛋白和缺失nifZ固氮菌突变种的ΔnifZ MoFe蛋白结晶所需的最适浓度有所不同.结果表明,该蛋白晶体可能为CrFe蛋白的晶体.

关键词 固氮菌突变种UW3 含铬培养基 固氮酶铬铁蛋白 晶体生长

*通讯作者

Key words: mutant UW3 of Azotobacter vinelandii, Cr containing medium, nitrogenase CrFe protein, crystalline growth