Li J D, Wang J W, Zhong Z P, Tu Y, Dong B
Sci Sin. 1980 Jul;23(7):897-904.
It has been demonstrated that a cytochrome b-containing ferritin is present in Azotobacter vinelandii. After DEAE cellulose chromatography and purification fractional precipitation by 50% of the saturated ammonium sulfate of the extract prepared from A. vinelandii cells, a hexagonal crystalline preparation is obtained. The protein contains 4--6% of nonheme iron. The protein molecule is made up of an electron dense iron core with a diameter of 70A and a protein shell with a diameter of 120A. The Fe core can be removed from the shell by the treatment with chelating and reducing agents. Electron micrographs and absorption spectra reveal that the protein shells are very similar before and after the removal of the core. The electrophoretic mobility and immunological properties of the Fe-free protein against the antibody of ferritin are very similar to those of the protein before the removal of the iron. From the above characteristics, it can be inferred that the protein belongs to ferritin. The protein part contains protoheme as prosthetic group and so it belongs to cytochrome b. Hence, the protein prepared from A. vinelandii is a kind of cytochrome b-containing ferritins. The possible role of the ferritin in biological nitrogen fixation is discussed in this paper.
已经证明，棕色固氮菌中存在一种含细胞色素b的铁蛋白。对从棕色固氮菌细胞制备的提取物进行DEAE纤维素色谱和50%饱和硫酸铵分级沉淀纯化后，得到一种六方晶体制剂。该蛋白质含有4%-6%的非血红素铁。蛋白质分子由直径为70埃的电子致密铁核和直径为120埃的蛋白质外壳组成。通过用螯合剂和还原剂处理，可以将铁核从外壳中去除。电子显微镜照片和吸收光谱显示，去除铁核前后蛋白质外壳非常相似。无铁蛋白质相对于铁蛋白抗体的电泳迁移率和免疫特性与去除铁之前的蛋白质非常相似。从上述特征可以推断，该蛋白质属于铁蛋白。蛋白质部分含有原血红素作为辅基，因此它属于细胞色素b。因此，从棕色固氮菌制备的蛋白质是一种含细胞色素b的铁蛋白。本文讨论了铁蛋白在生物固氮中的可能作用。
