棕色固氮菌变种UW_(45)缺辅基钼铁蛋白的分离及性质研究(Ⅰ)

ISOLATION OF THE COFACTOR-DEFICIENT MoFe-PROTEIN FROM A VINELANDII MUTANT STRAIN UW-45 AND THE STUDY OF ITS PROPERTIES

应用DEAE-11^(#)纤维素柱层析,结合无氧制备电泳从棕色固氮菌变种uw_(45)无细胞抽提液中分离得到了一种电泳纯蛋白质,回收率为18.4%。该蛋白与FeMoco重组可以催化乙炔还原成乙烯,比活可达5.85nM乙烯/分·毫克蛋白,比其无细胞抽提液活性提高22.7倍。该蛋白与FeMoco重组之后,电泳迁移率明显变慢,更接近棕色固氮菌钼铁蛋白,含铁量增加一倍,井含钼,分子量22万,可见光谱与棕色固氮菌钼铁蛋白的相同。因此,我们认为uw45缺辅基铜铁蛋白与FeMoco重组之后形成了类似棕色固氮菌钼铁蛋白的活性蛋白。

With the aid of cellulose chromatography and preparative electrophore-sis,a purified cofactor-deficient MoFe-protein has been obtained from A.V.mutant strain uw-45 with a yield of 18.4%.After reconstitution of the cofactor-deficient MoFe-protein with the FeMoco,a new active protein was formed with a molecular weight of 220,000.The active protein could reduces CH=CH to CH_(2)=CH_(3) having a specific activity of 5.85nM/min·mg protein as much as 22.7 times of the extracts of A.V.mutant strain uw-45.Similar to the MoFe-protein,the migration of the active protein during the course of electrophoresis was found to be slower than that of the cofactor-deficient MoFe-protein.Elemental analysis showed that the iron content was twice as much as that of the cofactor-deficient MoFe-protein.The visible absorption spectrum of the active protein was found to be identical with that of MoFe-protein.On the basis of the above results we postulate that the cofactor-deficient MoFe-protein can be transformed into MoFe-protein by combining with the FeMoco.