Eady R R
Biochem J. 1973 Nov;135(3):531-5. doi: 10.1042/bj1350531.
Sedimentation-velocity analyses of mixtures of the component proteins of nitrogenase of Klebsiella pneumoniae at a 1:1 molar ratio, showed a single peak of sedimentation coefficient (12.4S) considerably greater than that obtained for the larger (Fe+Mo-containing) protein centrifuged alone (10.4S). When the ratio exceeded 1:1 (the smaller Fe-containing protein in excess) an additional peak corresponding in sedimentation coefficient (about 4.5S) to free Fe-containing protein appeared. When proteins, which had been inactivated by exposure to air were used, no interaction occurred. Na(2)S(2)O(4) at 2mm both reversed and prevented interaction between the two proteins; sedimentation coefficients corresponded to those of the proteins when centrifuged alone. These results demonstrate the formation of a complex between the nitrogenase proteins, and, together with data of activity titration curves, are consistent with the formulation of the nitrogenase complex of K. pneumoniae as (Fe-containing protein)-(Fe+Mo-containing protein).
对肺炎克雷伯菌固氮酶各组成蛋白以1:1摩尔比混合进行沉降速度分析，结果显示沉降系数的单一峰（12.4S）远大于单独离心较大的（含Fe + Mo）蛋白时得到的沉降系数（10.4S）。当比例超过1:1（较小的含铁蛋白过量）时，出现了一个沉降系数（约4.5S）与游离含铁蛋白相对应的额外峰。当使用经空气暴露而失活的蛋白时，未发生相互作用。2 mM的Na₂S₂O₄既能逆转也能阻止两种蛋白之间的相互作用；沉降系数与单独离心时蛋白的沉降系数相对应。这些结果证明了固氮酶蛋白之间形成了复合物，并且与活性滴定曲线数据一起，与将肺炎克雷伯菌固氮酶复合物表示为（含铁蛋白）-（含Fe + Mo蛋白）的形式一致。
