title: Observation of two modes of inhibition of human microsomal prostaglandin E synthase 1 by the cyclopentenone 15-deoxy-Δ(12,14)-prostaglandin J(2).
abstract: Microsomal prostaglandin E synthase 1 (MPGES1) is an enzyme that produces the pro-inflammatory molecule prostaglandin E(2) (PGE(2)). Effective inhibitors of MPGES1 are of considerable pharmacological interest for the selective control of pain, fever, and inflammation. The isoprostane, 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)), a naturally occurring degradation product of prostaglandin D(2), is known to have anti-inflammatory properties. In this paper, we demonstrate that 15d-PGJ(2) can inhibit MPGES1 by covalent modification of residue C59 and by noncovalent inhibition through binding at the substrate (PGH(2)) binding site. The mechanism of inhibition is dissected by analysis of the native enzyme and the MPGES1 C59A mutant in the presence of glutathione (GSH) and glutathione sulfonate. The location of inhibitor adduction and noncovalent binding was determined by triple mass spectrometry sequencing and with backbone amide H/D exchange mass spectrometry. The kinetics, regiochemistry, and stereochemistry of the spontaneous reaction of GSH with 15d-PGJ(2) were determined. The question of whether the anti-inflammatory properties of 15d-PGJ(2) are due to inhibition of MPGES1 is discussed.
authors.affiliation: Departments of Chemistry and Biochemistry, Center in Molecular Toxicology, and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232-0146, United States.
authors.forename: Edward B
authors.initials: EB
authors.lastname: Prage
authors.forename: Ralf
authors.initials: R
authors.lastname: Morgenstern
authors.forename: Per-Johan
authors.initials: PJ
authors.lastname: Jakobsson
authors.forename: Donald F
authors.initials: DF
authors.lastname: Stec
authors.forename: Markus W
authors.initials: MW
authors.lastname: Voehler
authors.forename: Richard N
authors.initials: RN
authors.lastname: Armstrong
mesh_terms: D000893:Anti-Inflammatory Agents / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D005978:Glutathione / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000188:drug therapy; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry; D008861:Microsomes / Q000201:enzymology* / Q000378:metabolism; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000071876:Prostaglandin-E Synthases
chemical_list: C477819:15-deoxyprostaglandin J2; D000893:Anti-Inflammatory Agents; C040136:glutathione sulfonate; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; D005978:Glutathione; D015230:Prostaglandin D2