Formate dehydrogenases molybdopterin

The three known crystal structures of molybdopterin-containing enzymes are from members of the first two families the aldehyde oxido-reductase from D. gigas (MOP) belongs to the xanthine oxidase family (199, 200), whereas the DMSO reductases from Rhodobacter (R.) cap-sulatus (201) and from/ , sphaeroides (202) and the formate dehydrogenase from E. coli (203) are all members of the second family of enzymes. There is a preliminary report of the X-ray structure for enzymes of the sulfite oxidase family (204). 

Boyington JC, VN Gladyshev, SV Khangulov, TC Stadtman, PD Sun (1997) Crystal structure of formate dehydrogenase H catalysis involving Mo, molybdopterin, selenocysteine, and an Fe4S4 cluster. Science 275 1305-1308. 

Johnson JL, Bastian NR, Schauer NL, et al. 1991. Identification of molybdopterin guanine dinucleotide in formate dehydrogenase from Methanobacterium formi-cicum. FEMS Microbiol Lett 77 2-3. 

Formate dehydrogenases from many bacteria contain molybdopterin and also often selenium (Table 15-4).664/665 A membrane-bound Mo-containing formate dehydrogenase is produced by E. coli grown anaerobically in the presence of nitrate. Under these circumstances it is coupled to nitrate reductase via an electron-transport chain in the membranes which permits oxidation of formate by nitrate (Eq. 18-26). This enzyme is also a multisubunit protein.665 666 Two other Mo- and Se- containing formate dehydrogenases are produced... 

Nicotinic acid hydroxylase from Clostridium barkerii catalyzes reaction (55), the hydroxylation of a pyridine group, and has similarities to xanthine dehydrogenase. Nicotinic acid hydroxylase is a 300 000 molecular weight flavoprotein containing iron-sulfur and FAD centres, selenium1034 and a molybdopterin cofactor.1035 Formate dehydrogenase contains selenium as selenocysteine,1036 but this does not appear to be the case for nicotinic acid hydroxylase. The possibility that the selenium is incorporated into the molybdopterin cannot be excluded at present. 

Khangulov, S. V., Gladyshev, V. N., Dismukes, G. C., and Stadtman, T. C., 1998, Selenium-containing formate dehydrogenase H from Escherichia coli a molybdopterin enzyme that catalyzes formate oxidation without oxygen transfer. Biochemistry 37 351893528. 

FDH = Formate dehydrogenase CAR = Carboxyhc acid reductase FMDH = Formylmethanofuran dehydrogenase MFR = Methanofuran AOR = Aldehyde ferredoxin oxi-doreductase MPT = Molybdopterin Fdox = Oxidized ferredoxin Fdred = Reduced ferredoxin FOR = Formaldehyde ferredoxin oxidoreductase EXAFS = X-ray absorption edge fine structure kDa = Kilodaltons EPR = Electron paramagnetic resonance. 

An enzyme-bound molybdopterin is found in methanogen formate dehydrogenase, and formylmethanofuran dehydrogenase [123,124]. It is distinct from the H4MPT coenzymes used in the methanogenic pathway (see the enzyme sections for detail). 

Formate dehydrogenase H from E. coli contains selenocysteine (SeCys), molybdenum, two molybdopterin guanine dinucleotide (MGD) cofactors, and an Fe4S4... 

The first hint of an essential role of molybdenum in metabolism came from the discovery that animals raised on a diet deficient in molybdenum had decreased liver xanthine oxidase activity. There is no evidence that xanthine oxidase is essential for all life, but a human genetic deficiency of sulfite oxidase or of its molybdopterin coenzyme can be lethal.646,646a,b The conversion of molybdate into the molybdopterin cofactor in E. coli depends upon at least five genes.677 In Drosophila the addition of the cyanolyzable sulfur (Eq. 16-64) is the final step in formation of xanthine dehydrogenase.678 It is of interest that sulfur (S°) can be transferred from rhodanese (see Eq. 24-45), or from a related mercaptopyruvate sulfurtransferase679 into the desulfo form of xanthine oxidase to generate an active enzyme.680... 

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