title: The nature of molybdenum-cofactor.
abstract: In vitro assembly of Neurospora crassa NADPH-nitrate reductase (EC1.6.6.2) could be effected by combing the nitrate induced Neurospora crassa mutant nit-1 with the extract of any known molybdenum-containing enzyme. The process involves the participation of a molybdenum-cofactor contributed by the molybdenum-enzyme fraction. This paper emphasizes two points: Firstly, the indispensable role played by EDTA in the viability of Mo-cofactor and secondly, the nature of Mo-cofactor predicated by our previous work is supported by concrete experimental results. Recent experiments with Chelax-100 column provide evidence that the in vitro formation of Neurospora NADPH-nitrate reductase involves EDTA and the latter may take part in the formation of a molybdenum, labile sulfide and EDTA complex. In addition to 10(-2) M sodium molybdate, both EDTA and reducing agent are required to activate the cofactor in the Chelax-100 column eluate. The cofactor is of low molecular weight and devoid of protein as was predicated. To substantiate those predications, concrete experimental results are provided.
mesh_terms: D004492:Edetic Acid / Q000378:metabolism; D008982:Molybdenum / Q000378:metabolism*; D009491:Neurospora / Q000201:enzymology*; D009492:Neurospora crassa / Q000201:enzymology*; D009565:Nitrate Reductases / Q000096:biosynthesis*; D014969:Xanthine Oxidase / Q000494:pharmacology
chemical_list: D008982:Molybdenum; D004492:Edetic Acid; D014969:Xanthine Oxidase; D009565:Nitrate Reductases