Lewis N J, Scazzocchio C
Eur J Biochem. 1977 Jun 15;76(2):441-6. doi: 10.1111/j.1432-1033.1977.tb11613.x.
The cnx- group of mutants of Aspergillus nidulans lacks xanthine dehydrogenase (xanthine: NAD+ oxidoreductase, EC 1.2.1.37) and nitrate reductase (EC 1.6.6.3) activities and are thought to be defective in the synthesis of a molybdenum-containing cofactor, 'cnx', common to xanthine dehydrogenase and nitrate reductase [Pateman, J.A., Rever, B.M., Cove, D.J. and Roberts, D.B. (1964) Nature (Lond.) 201, 58-60]. The cnx cofactor has a role in maintaining the aggregated multimeric structure of nitrate reductase [MacDonald, D.W., Cove, D.J. and Coddington, A. (1974) Mol. Gen. Genet. 128, 187-199]. We report here that, in cnx- mutants grown under conditions inducing xanthine dehydrogenase I, a species cross-reacting with antisera to the native enzyme and of half its molecular weight is present, together with cross-reacting molecules of similar molecular weight to the native enzyme. This suggests that the cnx cofactor has a role in maintaining the aggregated structure of xanthine dehydrogenase I. Both cross-reacting species are capable of passing reducing equivalents from NADH to a tetrazolium salt, showing that the cnx cofactor is not necessary for enzymic activity towards NADH.
构巢曲霉的cnx - 突变体组缺乏黄嘌呤脱氢酶（黄嘌呤：NAD⁺氧化还原酶，EC 1.2.1.37）和硝酸还原酶（EC 1.6.6.3）活性，被认为在合成一种含钼辅因子“cnx”方面存在缺陷，该辅因子是黄嘌呤脱氢酶和硝酸还原酶所共有的[帕特曼，J.A.，雷弗，B.M.，科夫，D.J.和罗伯茨，D.B.（1964年）《自然》（伦敦）201, 58 - 60]。cnx辅因子在维持硝酸还原酶的聚集多聚体结构中起作用[麦克唐纳，D.W.，科夫，D.J.和科丁顿，A.（1974年）《分子遗传学与普通遗传学》128, 187 - 199]。我们在此报告，在诱导黄嘌呤脱氢酶I的条件下生长的cnx - 突变体中，存在一种与针对天然酶的抗血清发生交叉反应且分子量为其一半的物质，以及与天然酶分子量相似的交叉反应分子。这表明cnx辅因子在维持黄嘌呤脱氢酶I的聚集结构中起作用。这两种交叉反应物质都能够将还原当量从NADH传递给四唑盐，表明cnx辅因子对于针对NADH的酶活性不是必需的。
