title: Characterisation of the pterin molybdenum cofactor in dimethylsulfoxide reductase of Rhodobacter capsulatus.
abstract: Analysis of dimethylsulfoxide reductase from Rhodobacter capsulatus showed that it contained 1 mol Mo and 2 mol GMP. This indicates that the molybdenum cofactor in dimethylsulfoxide reductase is bis(molybdopterin guanine dinucleotide) molybdenum. The absorption spectrum of the molybdopterin guanine dinucleotide released from dimethylsulfoxide reductase after denaturation of the holoenzyme was compared with those of pterin standards of known redox state. The spectra were most similar to pterin standards in the dihydro state and oxidised state. The reduction of 2,6-dichloroindophenol by molybdopterin guanine dinucleotide released from dimethylsulfoxide reductase and by pterin standards was also measured and approximately 2 mol electrons/2 mol molybdopterin guanine dinucleotide were found to reduce 2,6-dichloroindophenol. These results are consistent with the presence of one molybdopterin guanine dinucleotide moiety with a pyrazine ring at the oxidation level of a dihydropteridine and one molybdopterin guanine dinucleotide moiety with a pyrazine ring at the oxidation level of a fully aromatic pteridine. It is suggested that the pyrazine ring of Q-molybdopterin guanine dinucleotide is fully aromatic and contains a 5,6 double bond.
authors.affiliation: Department of Microbiology, The University of Queensland, Brisbane, Australia.
authors.forename: P S
authors.initials: PS
authors.lastname: Solomon
authors.forename: I
authors.initials: I
authors.lastname: Lane
authors.forename: G R
authors.initials: GR
authors.lastname: Hanson
authors.forename: A G
authors.initials: AG
authors.lastname: McEwan
mesh_terms: D015086:2,6-Dichloroindophenol / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry; D003067:Coenzymes / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport; D006150:Guanine Nucleotides / Q000737:chemistry* / Q000378:metabolism; D006157:Guanosine Monophosphate / Q000032:analysis; D007506:Iron-Sulfur Proteins; D008667:Metalloproteins / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D008982:Molybdenum / Q000032:analysis; D000090006:Molybdenum Cofactors; D009942:Organometallic Compounds / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010710:Phosphates / Q000032:analysis; D011489:Protein Denaturation; D011621:Pteridines / Q000737:chemistry* / Q000378:metabolism; D011622:Pterins / Q000737:chemistry / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000737:chemistry / Q000201:enzymology*; D013053:Spectrophotometry
chemical_list: D015086:2,6-Dichloroindophenol; D001426:Bacterial Proteins; D003067:Coenzymes; D006150:Guanine Nucleotides; D006157:Guanosine Monophosphate; D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D009942:Organometallic Compounds; D010088:Oxidoreductases; D010710:Phosphates; D011621:Pteridines; D011622:Pterins; C106961:bis(molybdopterin guanine dinucleotide)molybdenum; C063761:molybdopterin guanine dinucleotide; C022261:molybdopterin; C045664:dimethyl sulfoxide reductase