Kramer S, Hageman R V, Rajagopalan K V
Arch Biochem Biophys. 1984 Sep;233(2):821-9. doi: 10.1016/0003-9861(84)90511-3.
The reduced, metal-free pterin of the molybdenum cofactor has been termed molybdopterin. Oxidation of any molybdopterin-containing protein in the presence or absence of iodine yields oxidized molybdopterin derivatives termed Form A and Form B, respectively. Application of these procedures to whole cells and cell extracts has demonstrated the presence of molybdopterin in wild-type Neurospora crassa, and its absence in the cofactor-deficient mutant nit-1. In order to demonstrate that the reconstitution of nitrate reductase activity in nit-1 extracts results from the incorporation of molybdopterin into the apoprotein, active molybdopterin, free of contaminating amino acids or peptides, was isolated from chicken liver sulfite oxidase and used in the reconstitution system. The results show that, during reconstitution, exogenous molybdopterin is specifically incorporated into the nitrate reductase protein, confirming the role of molybdopterin as the organic moiety of the molybdenum cofactor.
钼辅因子的还原型无金属蝶呤被称为钼蝶呤。在有或没有碘存在的情况下，对任何含钼蝶呤的蛋白质进行氧化，分别产生被称为A形式和B形式的氧化钼蝶呤衍生物。将这些方法应用于全细胞和细胞提取物，已证明在野生型粗糙脉孢菌中存在钼蝶呤，而在辅因子缺陷型突变体nit-1中不存在。为了证明nit-1提取物中硝酸还原酶活性的重建是由于钼蝶呤掺入脱辅基蛋白，从鸡肝亚硫酸盐氧化酶中分离出不含污染氨基酸或肽的活性钼蝶呤，并用于重建系统。结果表明，在重建过程中，外源性钼蝶呤被特异性地掺入硝酸还原酶蛋白中，证实了钼蝶呤作为钼辅因子有机部分的作用。
