Redinbaugh M G, Campbell W H
Biochem Biophys Res Commun. 1983 Aug 12;114(3):1182-8. doi: 10.1016/0006-291x(83)90687-3.
We show that NADH:nitrate reductase from squash cotyledons can catalyze the reduction of ferric citrate. When nitrate reductase was purified to homogeneity using a two-step affinity chromatography procedure, an NADH:Fe(III)-citrate reductase activity copurified with it and had identical electrophoretic mobility to it. The iron reductase activity was optimum near pH 6.3, had an apparent Km for Fe(III)-citrate of 0.02 mM, and was inhibited by monospecific anti-nitrate reductase rabbit sera. Differential inhibition of the enzyme's activities indicated iron and nitrate were reduced at different sites. In addition to its role in nitrogen assimilation, nitrate reductase catalyzes ferric citrate reduction and could have a role in iron assimilation.
我们发现南瓜子叶中的NADH：硝酸还原酶能够催化柠檬酸铁的还原反应。当采用两步亲和层析法将硝酸还原酶纯化至同质状态时，一种NADH：Fe（III）-柠檬酸还原酶活性与之一同被纯化出来，并且其电泳迁移率与之相同。铁还原酶活性在pH 6.3左右时最佳，对Fe（III）-柠檬酸的表观Km值为0.02 mM，并且受到单特异性抗硝酸还原酶兔血清的抑制。对该酶活性的差异抑制表明铁和硝酸盐在不同位点被还原。除了在氮同化中的作用外，硝酸还原酶还催化柠檬酸铁的还原，并且可能在铁同化中发挥作用。
