L-N? -Nitroarginine-2,4-L-diaminobutyric amide All isoforms of NOS contain an N-terminal oxygenase di(Trifluoroacetic) salt domain with binding sites for L-arginine, cofactors (6R)-5,6,7,8-tetrahydrobiopterin (BH4) and heme, and a Product Number N 3411 linked C-terminal reductase domain with NADPH, FAD, Store at 2-8 °C FMN, and calmodulin binding sites. All isoforms require dimerization for activity. NOS isoforms all have PDZ Cas #: 244185-39-5 domains for protein-protein interactions with diverse NO2 Synonym: L-Arg -L-Dbu-NH2 – 2TFA binding partners ranging from scaffolding proteins to membrane receptors. For instance, nNOS interacts with N-methyl-D-aspartate (NMDA) receptor (NMDAR) via HN NHNO2 PDZ domains with the postsynaptic density (PSD-95) protein and the adaptor protein COOH-terminal PDZ NH ligand of nNOS (CAPON). CAPON binds and provides 2CF3COOH the link to the small G-protein, Dexras1 thus facilitating the nitrosylation and activation of Dexras 1 by nNOS. In H general, the proximity created in this type of protein- N NH 2 protein interaction is one of the posttranslation controls H2N O CONH that determines the timing, magnitude, and spatial 2 distribution of NOS and the release of its effector, NO.2

NO as a secondary messenger has proven to be a two- Product Description edged sword.1 NO produced by nNOS and eNOS is Molecular Formula: C H N O × 3 C HF O 10 22 8 4 2 3 2 indispensable in neurotransmission and the regulation Molecular Weight: 546.4 of vasasodilation. NO produced by iNOS is involved in defense against microbial pathogens. The L-N? -Nitroarginine-2,4-L-diaminobutyric amide is a overproduction of NO plays key roles in the pathology peptidomimetic potent isoform that is a selective of a wide range of disorders including diabetes, inhibitor of neuronal nitric oxide synthase. inflammatory diseases (septic shock, arthritis),

ischemia-reperfusion injury, stroke, neuropathic pain, Nitric oxide (NO) is an inorganic gaseous, labile radical and various chronic neurodegenerative diseases and a potent secondary messenger that is highly (Alzheimer’s, Parkinson’s, Huntington’s). reactive biochemically and highly diffusible.1 NO is generated physiologically by a family of enzymes, nitric Given the existence of the tissue specific NOS isoforms oxide synthases (NOS, E.C. 1.14.13.39). These and the important physiological roles of NO, isoform enzymes catalyze the oxidation of L-arginine substrate selectivity is highly desirable in NOS inhibitors as to L-cirtullline and nitric oxide. There are three therapeutic agents. General opinion in the field holds structurally distinct isoforms among NOS: two that eNOS must be spared for its activities in the constitutionally expressed, the neuronal NOS (nNOS, cardiovascular system. The different strategies NOS1) and endothelial NOS (eNOS, NOS3); and the employed by medicinal chemist for achieving isoform inducible form in macrophages and microglia in the selectivity targeted towards the different binding sites of nervous system (iNOS, NOS2). There is only a 50% NOS and performance of traditional NOS inhibitors primary sequence homology among the isoforms in have been reviewed.3 Most amino acid based inhibitors contrast to high sequence conservation across species. are irreversible and have minimal selectivity.

Nw-Nitro-L-arginine (Product No. N 5501) is relatively License Acknowledgement ? inactive for iNOS but IC50 values for nNOS and eNOS Cat # N3411 L-N -Nitroarginine-2,4-L-diaminobutyric are not dramat ically different. Similarly, although amide is manufactured and sold under license to US 2 7-nitroindazole (Product No. N 7778) has neuro- patent number 6,274,557 protective properties and has been described as a relatively selective nNOS inhibitor acting as a ligand to Cat # A5727 (4S)-N-(4-amino-5-[aminoethyl]- 1 the heme prosthetic group; it actually has minimally aminopentyl)-N’-nitroguanidine (US sn 60/300,130) different IC50 values for the three isoforms. In a series of related works beginning with the screening of a Related Product library of conformationally constrained arginine N-[(4S)-4-Amino-5-[(2-aminoethyl](amino] pentyl]-N’- analogues and following subsequent optimization, nitroguanidine (Product No. A 5727) L-N? -Nitroarginine-2,4-L-diaminobutyric amide (Product No. N 3411) and (4S)-N-(4-amino-5-[aminoethyl]amino- References pentyl)-N’-nitroguanidine (Product No. A 5727) was 1. Kerwin, J.F. Jr., et al., Nitric oxide: a new paradigm produced.4, 5 These compounds have by far the highest for second messengers. J. Med. Chem., 38, selectivity for nNOS particularly relative to activties on 4343-4362 (1995). eNOS thus achieving the imperative design goal of 2. Kone, B.C., et al., Protein interactions with nitric preserving the physiologically important eNOS function. oxide synthases: controlling the right time, the right place, and the right amount of nitric oxide. Am. J. In summary, both compounds, N-[(4S)-4-Amino-5-[(2- Physiol. Renal Physiol., 285, 178-190 (2003). aminoethyl](amino] pentyl]-N’-nitroguanidine (Product 3. Southan, G.J., and Szabo, C., Selective No. A 5727) and L-Nw-Nitroarginine-2.4-diaminobutyric pharmacological inhibition of distinct nitric oxide amide (Product No. N 3411), are potent and highly synthase isoforms. Biochem. Pharmacol., 51, targeted tools in the study of nNOS functions and 383-394 (1996). further discoveries of nNOS roles in neurodegenerative 4. Huang, H., et al., Synthesis and evaluation of disease. peptidomimetics as selective inhibitors and active site probes of nitric oxide synthases. J. Med. Chem., 43, 2938-2945 (2000). 5. Hah, J.M., et al., Reduced amide bond peptidomimetics. (4S)-N-(4-amino-5- [aminoakyl]aminopentyl)-N'-nitroguanidines, potent and highly selective inhibitors of neuronal nitric oxide synthase. J. Med. Chem., 44, 2667-2670 (2001).

KA/RP 04/05

Sigma brand products are sold through Sigma-Aldrich, Inc. Sigma-Aldrich, Inc. warrants that its products conform to the information contained in this and other Sigma-Aldrich publications. Purchaser must determine the suitability of the product(s) for their particular use. Additional terms and conditions may apply. Please see reverse side of the invoice or packing slip.