Miller R W, Eady R R
Plant Research Centre, Agriculture Canada, Ottawa, Ontario.
Biochem J. 1988 Dec 1;256(2):429-32. doi: 10.1042/bj2560429.
A comparison of the effect of temperature on the reduction of N2 by purified molybdenum nitrogenase and vanadium nitrogenase of Azotobacter chroococcum showed differences in behaviour. As the assay temperature was lowered from 30 degrees C to 5 degrees C N2 remained an effective substrate for V nitrogenase, but not Mo nitrogenase, since the specific activity for N2 reduction by Mo nitrogenase decreased 10-fold more than that of V nitrogenase. Activity cross-reactions between nitrogenase components showed the enhanced low-temperature activity to be associated with the Fe protein of V nitrogenase. The lower activity of homologous Mo nitrogenase components, although dependent on the ratio of MoFe protein to Fe protein, did not equal that of V nitrogenase even under conditions of high electron flux obtained at a 12-fold molar excess of Fe protein.
对温度对纯化的钼固氮酶和褐球固氮菌钒固氮酶还原N₂的影响进行比较，结果显示出行为上的差异。随着测定温度从30℃降至5℃，N₂仍然是钒固氮酶的有效底物，但不是钼固氮酶的有效底物，因为钼固氮酶还原N₂的比活性下降幅度比钒固氮酶大10倍。固氮酶组分之间的活性交叉反应表明，低温活性的增强与钒固氮酶的铁蛋白有关。同源钼固氮酶组分的活性较低，尽管依赖于钼铁蛋白与铁蛋白的比例，但即使在铁蛋白摩尔过量12倍获得的高电子通量条件下，也不等于钒固氮酶的活性。
