Identification of molybdopterins in molybdenum- and selenium-containing enzymes.
Selenium is coordinated to a molybdenum atom in nicotinic acid hydroxylase (NAH) from Clostridium barkeri and formate dehydrogenase H (FDH) from Escherichia coli. Selenium is present in FDH in a selenocysteine residue whereas in NAH in occurs in an unidentified labile cofactor. In this paper we describe a simple procedure for isolation and identification of molybdopterins from Mo-containing enzymes. The molybdopterin, after release from the protein with guanidine-hydrochloride, is reduced with KBH4, alkylated with iodoacetamide and separated on a reverse-phase HPLC column. The carboxam-idomethylated pterin compound is further characterized by UV spectroscopy and mass-spectrometry. We found that FDH contains molybdopterin guanine dinucleotide whereas NAH contains molybdopterin cytosine dinucleotide.
Gladyshev
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National Institutes of Health, Bethesda, MD 20892, USA.
Lecchi
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D003067:Coenzymes / Q000032:analysis*; D005560:Formate Dehydrogenases / Q000737:chemistry*; D013058:Mass Spectrometry; D008667:Metalloproteins / Q000032:analysis*; D015394:Molecular Structure; D008982:Molybdenum / Q000032:analysis*; D000090006:Molybdenum Cofactors; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry*; D011621:Pteridines / Q000032:analysis*; D012643:Selenium / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
D003067:Coenzymes; D005560:Formate Dehydrogenases; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D000587:Oxidoreductases Acting on CH-NH Group Donors; D011621:Pteridines; D012643:Selenium; C022261:molybdopterin; C021862:nicotinate dehydrogenase