Structures of nitric oxide synthase isoforms complexed with the inhibitor AR-R17477 suggest a rational basis for specificity and inhibitor design.
The high level of amino acid conservation and structural similarity of the substrate-binding sites of the oxygenase domains of the nitric oxide synthase (NOS) isoforms (eNOSoxy, iNOSoxy, nNOSoxy) make the interpretation of the structural basis of inhibitor isoform specificity a challenge, and provide few clues for the design of new selective compounds. Crystal structures of iNOSoxy and nNOSoxy complexed with the neuronal NOS-specific inhibitor AR-R17447 suggest that specificity is provided by the interaction of the chlorophenyl group with an isoform-unique substrate access channel residue (L337 in rat neuronal NOS, N115 in mouse inducible NOS). This is confirmed by biochemical analysis of site-directed mutants. Inhibitors combining guanidinium-like structural motifs with long chains specifically targeting this residue are good candidates for rational isoform-specific drug design. Based on this finding, modifications of AR-R17447 to improve the specificity for the human isoforms are suggested.
Fedorov
Roman
R
Max Planck Institut für Molekulare Physiologie, Abteilung Biophysikalische Chemie, Otto Hahn Strasse 11, 44227 Dortmund, Germany.
Vasan
Ryan
R
Ghosh
Dipak K
DK
Schlichting
Ilme
I
D000578:Amidines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D013876:Thiophenes / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
D000578:Amidines; D004791:Enzyme Inhibitors; D007527:Isoenzymes; C486880:N-(4-(2-((3-chlorophenylmethyl)amino)ethyl)phenyl)-2-thiophenecarboxamide; D013876:Thiophenes; D019001:Nitric Oxide Synthase