title: Mechanism of inhibition for N6022, a first-in-class drug targeting S-nitrosoglutathione reductase.
abstract: N6022 is a novel, first-in-class drug with potent inhibitory activity against S-nitrosoglutathione reductase (GSNOR), an enzyme important in the metabolism of S-nitrosoglutathione (GSNO) and in the maintenance of nitric oxide (NO) homeostasis. Inhibition of GSNOR by N6022 and related compounds has shown safety and efficacy in animal models of asthma, chronic obstructive pulmonary disease, and inflammatory bowel disease [Sun, X., et al. (2011) ACS Med. Chem. Lett. 2, 402-406]. N6022 is currently in early phase clinical studies in humans. We show here that N6022 is a tight-binding, specific, and fully reversible inhibitor of GSNOR with an IC(50) of 8 nM and a K(i) of 2.5 nM. We accounted for the fact that the NAD(+)- and NADH-dependent oxidation and reduction reactions, catalyzed by GSNOR are bisubstrate in nature in our calculations. N6022 binds in the GSNO substrate binding pocket like a competitive inhibitor, although in kinetic assays it behaves with a mixed uncompetitive mode of inhibition (MOI) toward the GSNO substrate and a mixed competitive MOI toward the formaldehyde adduct, S-hydroxymethylglutathione (HMGSH). N6022 is uncompetitive with cofactors NAD(+) and NADH. The potency, specificity, and MOI of related GSNOR inhibitor compounds are also reported.
authors.affiliation: N30 Pharmaceuticals, LLC, Boulder, Colorado 80301, United States.
authors.forename: Louis S
authors.initials: LS
authors.lastname: Green
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Chun
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Patton
authors.forename: Xicheng
authors.initials: X
authors.lastname: Sun
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Rosenthal
authors.forename: Jane P
authors.initials: JP
authors.lastname: Richards
mesh_terms: D000429:Alcohol Oxidoreductases / Q000037:antagonists & inhibitors; D000445:Aldehyde Oxidoreductases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology*; D001667:Binding, Competitive; D020134:Catalytic Domain; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D011758:Pyrroles / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D026422:S-Nitrosoglutathione / Q000378:metabolism
chemical_list: D001549:Benzamides; D004791:Enzyme Inhibitors; C571360:N6022; D011758:Pyrroles; D011994:Recombinant Proteins; D026422:S-Nitrosoglutathione; D000429:Alcohol Oxidoreductases; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent