3jta
Structure of neuronal nitric oxide synthase heme domain in the ferrous state complexed with N~5~-[4-(methylsulfanyl)butanimidoyl]-L-ornithine
Structural highlights
FunctionNOS1_RAT Produces nitric oxide (NO) which is a messenger molecule with diverse functions throughout the body. In the brain and peripheral nervous system, NO displays many properties of a neurotransmitter. Inhibitory transmitter for non-adrenergic and non-cholinergic nerves in the colorectum. Probably has nitrosylase activity and mediates cysteine S-nitrosylation of cytoplasmic target proteins such SRR. Inhibitory transmitter for non-adrenergic and non-cholinergic nerves in the colorectum. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe heme-thioether ligand interaction often occurs between heme iron and native methionine ligands, but thioether-based heme-coordinating (type II) inhibitors are uncommon due to the difficulty in stabilizing the Fe-S bond. Here, a thioether-based inhibitor (3) of neuronal nitric oxide synthase (nNOS) was designed, and its binding was characterized by spectrophotometry and crystallography. A crystal structure of inhibitor 3 coordinated to heme iron was obtained, representing, to our knowledge, the first crystal structure of a thioether inhibitor complexed to any heme enzyme. A series of related potential inhibitors (4-8) also were evaluated. Compounds 4-8 were all found to be type I (non-heme-coordinating) inhibitors of ferric nNOS, but 4 and 6-8 were found to switch to type II upon heme reduction to the ferrous state, reflecting the higher affinity of thioethers for ferrous heme than for ferric heme. Contrary to what has been widely thought, thioether-heme ligation was found not to increase inhibitor potency, illustrating the intrinsic weakness of the thioether-ferric heme linkage. Subtle changes in the alkyl groups attached to the thioether sulfur caused drastic changes in the binding conformation, indicating that hydrophobic contacts play a crucial role in stabilizing the thioether-heme coordination. Heme-Coordinating Inhibitors of Neuronal Nitric Oxide Synthase. Iron-Thioether Coordination Is Stabilized by Hydrophobic Contacts without Increased Inhibitor Potency.,Martell JD, Li H, Doukov T, Martasek P, Roman LJ, Soltis M, Poulos TL, Silverman RB J Am Chem Soc. 2009 Dec 16. PMID:20014790[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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