title: The structure of a molybdopterin precursor. Characterization of a stable, oxidized derivative.
abstract: An oxidized pterin species, termed compound Z, has been isolated from molybdenum cofactor-deficient mutants of Escherichia coli and shown to be the direct product of oxidation of a molybdopterin precursor which accumulates in these mutants. The complete structural characterization of compound Z has been accomplished. A carbonyl function at C-1' of the 6-alkyl side chain can be reacted with 2,4-dinitrophenylhydrazine to yield a phenylhydrazone and can be reduced with borohydride, producing a mixture of two enantiomers, each with a hydroxyl group on C-1'. Compound Z contains one phosphate/pterin and no sulfur. The phosphate group is insensitive to alkaline phosphatase and to a number of phosphodiesterases but is quantitatively released as inorganic phosphate by mild acid hydrolysis. From 31P and 1H NMR of compound Z it was inferred that the phosphate is bound to C-2' and C-4' of a 4-carbon side chain, forming a 6-membered cyclic structure. Mass spectral analysis showed an MH+ ion with an exact mass of 344.0401 corresponding to the molecular formula C10H11N5O7P, confirming the proposed structure.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: J L
authors.initials: JL
authors.lastname: Johnson
authors.forename: M M
authors.initials: MM
authors.lastname: Wuebbens
authors.forename: K V
authors.initials: KV
authors.lastname: Rajagopalan
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002645:Chickens; D003067:Coenzymes; D004926:Escherichia coli / Q000378:metabolism; D007422:Intestines / Q000201:enzymology; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008667:Metalloproteins / Q000302:isolation & purification; D015394:Molecular Structure; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D009154:Mutation; D010758:Phosphorus / Q000032:analysis; D011621:Pteridines / Q000302:isolation & purification; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013455:Sulfur / Q000032:analysis
chemical_list: D000469:Alkaline Phosphatase; D003067:Coenzymes; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D010758:Phosphorus; D011621:Pteridines; D013455:Sulfur; C022261:molybdopterin