PMID: 14718923 , Related PDB ids: 1P6H, 1P6I, 1P6J, 1P6K, 1P6L, 1P6M, 1P6N, 1Q2O

Authors:

Flinspach ML, Li H, Jamal J, Yang W, Huang H, Hah JM, Gomez-Vidal JA, Litzinger EA, Silverman RB, Poulos TL

Title:

Structural basis for dipeptide amide isoform-selective inhibition of neuronal nitric oxide synthase.

Journal:

Nat Struct Mol Biol. 2004 Jan;11(1):54-9. Epub 2003 Dec 29.

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.