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Publication Abstract from PubMed

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.

Structural basis for dipeptide amide isoform-selective inhibition of neuronal nitric oxide synthase.,Flinspach ML, Li H, Jamal J, Yang W, Huang H, Hah JM, Gomez-Vidal JA, Litzinger EA, Silverman RB, Poulos TL Nat Struct Mol Biol. 2004 Jan;11(1):54-9. Epub 2003 Dec 29. PMID:14718923^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.