Structural basis for dipeptide amide isoform-selective inhibition of neuronal nitric oxide synthase.
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.
Flinspach
Mack L
ML
Department of Molecular Biology and Biochemistry and the Program in Macromolecular Structure, University of California, Irvine, California 92697-3900, USA.
Li
Huiying
H
Jamal
Joumana
J
Yang
Weiping
W
Huang
Hui
H
Hah
Jung-Mi
JM
Gómez-Vidal
José Antonio
JA
Litzinger
Elizabeth A
EA
Silverman
Richard B
RB
Poulos
Thomas L
TL
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
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