Ketchum P A, Downey R J
Biochim Biophys Acta. 1975 Apr 7;385(2):354-61. doi: 10.1016/0304-4165(75)90364-5.
Extracts of Aspergillus nidulans wild type (bi-1) and the nitrate reductase mutant niaD-17 were active in the in vitro restoration of NADPH-dependent nitrate reductase when mixed with extracts of Neurospora crassa, nit-1. Among the A. nidulans cnx nitrate reductase mutants tested, only the molybdenum repair mutant, cnxE-14 grown in the presence of 10-minus 3 M Na2 MoO4 was active in the restoration assay. Aspergillus extracts contained an inhibitor(s) which was measured by the decrease in NADPH-dependent nitrate reductase formed when extracts of Rhodospirillum rubrum and N. crassa, nit-1 were incubated at room temperature. The inhibition by extracts of A. nidulans, bi-1, cnxE-14, cnxG-4 and cnxH-3 was a linear function of time and a logarithmic function of the protein concentration in the extract. The molybdenum content of N. crassa wild type and nit-1 mycelia were found to be similar, containing approx. 10 mu g molybdenum/mg dry mycelium. The NADPH-dependent cytochrome c reductase associated with nitrate reductase was purified from both strains. The NADPH-dependent cytochrome c reductase associated with nitrate reductase was purified from both strains. The enzyme purified from wild-type N. crassa contained more than 1 mol of molybdenum per mol of enzyme, whereas the enzyme purified from nit-1 contained negligible amounts of molybdenum.
构巢曲霉野生型（bi - 1）和硝酸还原酶突变体niaD - 17的提取物与粗糙脉孢菌nit - 1的提取物混合时，在体外对依赖NADPH的硝酸还原酶具有恢复活性。在所测试的构巢曲霉cnx硝酸还原酶突变体中，只有在10的负3次方M Na2MoO4存在下生长的钼修复突变体cnxE - 14在恢复试验中具有活性。构巢曲霉提取物含有一种抑制剂，通过在室温下将红螺菌和粗糙脉孢菌nit - 1的提取物孵育时形成的依赖NADPH的硝酸还原酶的减少来测定。构巢曲霉bi - 1、cnxE - 14、cnxG - 4和cnxH - 3提取物的抑制作用是时间的线性函数和提取物中蛋白质浓度的对数函数。发现粗糙脉孢菌野生型和nit - 1菌丝体的钼含量相似，约为每毫克干菌丝体含10微克钼。从这两个菌株中都纯化了与硝酸还原酶相关的依赖NADPH的细胞色素c还原酶。从野生型粗糙脉孢菌中纯化的酶每摩尔酶含有超过1摩尔的钼，而从nit - 1中纯化的酶含有的钼量可忽略不计。
