title: Structural basis for dipeptide amide isoform-selective inhibition of neuronal nitric oxide synthase.
abstract: Three nitric oxide synthase (NOS) isoforms, eNOS, nNOS and iNOS, generate nitric oxide (NO) crucial to the cardiovascular, nervous and host defense systems, respectively. Development of isoform-selective NOS inhibitors is of considerable therapeutic importance. Crystal structures of nNOS-selective dipeptide inhibitors in complex with both nNOS and eNOS were solved and the inhibitors were found to adopt a curled conformation in nNOS but an extended conformation in eNOS. We hypothesized that a single-residue difference in the active site, Asp597 (nNOS) versus Asn368 (eNOS), is responsible for the favored binding in nNOS. In the D597N nNOS mutant crystal structure, a bound inhibitor switches to the extended conformation and its inhibition of nNOS decreases >200-fold. Therefore, a single-residue difference is responsible for more than two orders of magnitude selectivity in inhibition of nNOS over eNOS by L-N(omega)-nitroarginine-containing dipeptide inhibitors.
authors.affiliation: Department of Molecular Biology and Biochemistry and the Program in Macromolecular Structure, University of California, Irvine, California 92697-3900, USA.
authors.forename: Mack L
authors.initials: ML
authors.lastname: Flinspach
authors.forename: Huiying
authors.initials: H
authors.lastname: Li
authors.forename: Joumana
authors.initials: J
authors.lastname: Jamal
authors.forename: Weiping
authors.initials: W
authors.lastname: Yang
authors.forename: Hui
authors.initials: H
authors.lastname: Huang
authors.forename: Jung-Mi
authors.initials: JM
authors.lastname: Hah
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Gómez-Vidal
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Litzinger
authors.forename: Richard B
authors.initials: RB
authors.lastname: Silverman
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Poulos
mesh_terms: D000577:Amides / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D020134:Catalytic Domain; D002417:Cattle; D018360:Crystallography, X-Ray; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D066298:In Vitro Techniques; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D020033:Protein Isoforms / Q000737:chemistry / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D051381:Rats; D055672:Static Electricity
chemical_list: D000577:Amides; D004151:Dipeptides; D004791:Enzyme Inhibitors; D020033:Protein Isoforms; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496316:Nos3 protein, rat