1M8D

inducible nitric oxide synthase with Chlorzoxazone bound

Summary for 1M8D

• Entry DOI: 10.2210/pdb1m8d/pdb
• Related: 1M8E 1M8I 1M9J 1M9K 1M9M 1M9Q 1M9R 1M9T 1MIH 1NOD 3NOD
• Descriptor: Inducible Nitric Oxide Synthase, SULFATE ION, PROTOPORPHYRIN IX CONTAINING FE, ... (8 entities in total)
• Functional Keywords: inhibitor-induced conformational change, oxidoreductase
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 2
• Total formula weight: 103017.22

Authors

Rosenfeld, R.J.,Garcin, E.D.,Panda, K.,Andersson, G.,Aberg, A.,Wallace, A.V.,Stuehr, D.J.,Tainer, J.A.,Getzoff, E.D. (deposition date: 2002-07-24, release date: 2002-08-14, Last modification date: 2024-02-14)

Primary citation

Rosenfeld, R.J.,Garcin, E.D.,Panda, K.,Andersson, G.,Aberg, A.,Wallace, A.V.,Morris, G.M.,Olson, A.J.,Stuehr, D.J.,Tainer, J.A.,Getzoff, E.D.
Conformational Changes in Nitric Oxide Synthases Induced by Chlorzoxazone and Nitroindazoles: Crystallographic and Computational Analyses of Inhibitor Potency
Biochemistry, 41:13915-13925, 2002

PubMed Abstract: Nitric oxide is a key signaling molecule in many biological processes, making regulation of nitric oxide levels highly desirable for human medicine and for advancing our understanding of basic physiology. Designing inhibitors to specifically target one of the three nitric oxide synthase (NOS) isozymes that form nitric oxide from the L-Arg substrate poses a significant challenge due to the overwhelmingly conserved active sites. We report here 10 new X-ray crystallographic structures of inducible and endothelial NOS oxygenase domains cocrystallized with chlorzoxazone and four nitroindazoles: 5-nitroindazole, 6-nitroindazole, 7-nitroindazole, and 3-bromo-7-nitroindazole. Each of these bicyclic aromatic inhibitors has only one hydrogen bond donor and therefore cannot form the bidentate hydrogen bonds that the L-Arg substrate makes with Glu371. Instead, all of these inhibitors induce a conformational change in Glu371, creating an active site with altered molecular recognition properties. The cost of this conformational change is approximately 1-2 kcal, based on our measured constants for inhibitor binding to the wild-type and E371A mutant proteins. These inhibitors derive affinity by pi-stacking above the heme and replacing both intramolecular (Glu371-Met368) and intermolecular (substrate-Trp366) hydrogen bonds to the beta-sheet architecture underlying the active site. When bound to NOS, high-affinity inhibitors in this class are planar, whereas weaker inhibitors are nonplanar. Isozyme differences were observed in the pterin cofactor site, the heme propionate, and inhibitor positions. Computational docking predictions match the crystallographic results, including the Glu371 conformational change and inhibitor-binding orientations, and support a combined crystallographic and computational approach to isozyme-specific NOS inhibitor analysis and design.

PubMed: 12437348
DOI: 10.1021/bi026313j

Experimental method

X-RAY DIFFRACTION (2.35 Å)