title: Structure and reversible pyran formation in molybdenum pyranopterin dithiolene models of the molybdenum cofactor.
abstract: The syntheses and X-ray structures of two molybdenum pyranopterin dithiolene complexes in biologically relevant Mo(4+) and Mo(5+) states are reported. Crystallography reveals that these complexes possess a pyran ring formed through a spontaneous cyclization reaction of a dithiolene side-chain hydroxyl group at a C═N bond of the pterin. NMR data on the Mo(4+) complex suggest that a reversible pyran ring cyclization occurs in solution. These results provide experimental evidence that the pyranopterin dithiolene ligand in molybdenum and tungsten enzymes could participate in catalysis through dynamic processes modulated by the protein.
authors.affiliation: Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010-2899, United States.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Williams
authors.forename: Yichun
authors.initials: Y
authors.lastname: Fu
authors.forename: Glenn P A
authors.initials: GP
authors.lastname: Yap
authors.forename: Sharon J Nieter
authors.initials: SJ
authors.lastname: Burgmayer
mesh_terms: D003067:Coenzymes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D008024:Ligands; D008667:Metalloproteins / Q000737:chemistry*; D008958:Models, Molecular; D008982:Molybdenum / Q000737:chemistry*; D000090006:Molybdenum Cofactors; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000145:classification; D011621:Pteridines / Q000737:chemistry*; D011622:Pterins / Q000737:chemistry*
chemical_list: D003067:Coenzymes; D008024:Ligands; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D009942:Organometallic Compounds; D011621:Pteridines; D011622:Pterins; C418404:bis(dithiolene)molybdenum (IV); C490076:pyranopterin; C022261:molybdopterin