Study Of Nitric Oxide Synthase Research Articles

The Study of Nitric Oxide Synthase 3 (NOS3) T-786C and 4a4b Gene Polymorphism in Iranian Men with Varicocele

The Study of Nitric Oxide Synthase 3 (NOS3) T-786C and 4a4b Gene Polymorphism in Iranian Men with Varicocele

Novel choline analog 2-(4-((1-phenyl-1H-pyrazol-4-yl)methyl)piperazin-1-yl)ethan-1-ol produces sympathoinhibition, hypotension, and antihypertensive effects.

The search for new drugs remains an important focus for the safe and effective treatment of cardiovascular diseases. Previous evidence has shown that choline analogs can offer therapeutic benefit for cardiovascular complications. The current study investigates the effects of 2-(4-((1-phenyl-1H-pyrazol-4-yl)methyl)piperazin-1-yl)ethan-1-ol (LQFM032) on cardiovascular function and cholinergic-nitric oxide signaling. Synthesized LQFM032 (0.3, 0.6, or 1.2mg/kg) was administered by intravenous and intracerebroventricular routes to evaluate the potential alteration of mean arterial pressure, heart rate, and renal sympathetic nerve activity of normotensive and hypertensive rats. Vascular function was further evaluated in isolated vessels, while pharmacological antagonists and computational studies of nitric oxide synthase and muscarinic receptors were performed to assess possible mechanisms of LQFM032 activity. The intravenous and intracerebroventricular administration of LQFM032 elicited a temporal reduction in mean arterial pressure, heart rate, and renal sympathetic nerve activity of rats. The cumulative addition of LQFM032 to isolated endothelium-intact aortic rings reduced vascular tension and elicited a concentration-dependent relaxation. Intravenous pretreatment with L-NAME (nitric oxide synthase inhibitor), atropine (nonselective muscarinic receptor antagonist), pirenzepine, and 4-DAMP (muscarinic M1 and M3 subtype receptor antagonist, respectively) attenuated the cardiovascular effects of LQFM032. These changes may be due to a direct regulation of muscarinic signaling as docking data shows an interaction of choline analog with M1 and M3 but not nitric oxide synthase. Together, these findings demonstrate sympathoinhibitory, hypotensive, and antihypertensive effects of LQFM032 and suggest the involvement of muscarinic receptors.

The reaction of oximes with 4-phenyl-1,2,4-triazoline-3,5-dione to produce nitric oxide – Model compounds for nitric oxide synthase

Certain oximes form nitric oxide upon reaction with 4-phenyl-1,2,4-triazole-3,5-dione (PTAD). The oximes appear to undergo an Alder-ene reaction with the PTAD enophile to form a nitroso intermediate capable of dimerization and/or nitric oxide formation. Upon exposure to oxygen, the nitroso compounds eventually form ketones. This reaction may serve as a model for the study of nitric oxide synthase (NOS), the enzyme responsible for physiological production of nitric oxide. NOS is known to produce an oxime intermediate which reacts with oxygen to produce nitric oxide and citrulline.

Homology modelling and molecular docking studies of nitric oxide synthase (inducible) of Gallus gallus

BackgroundNitric oxide synthase inducible (iNOS) inhibits the proliferation of T-lymphocytes and its role has been associated in disease such as cancer. Various studies have also found out the expression and the activity of iNOS in cancer. Thus requiring attention for novel inhibitors against this enzyme. MethodsIn the present study, the three-dimensional structure of iNOS of Gallus gallus was generated by homology modelling using Modeller 9v8. The generated model was accessed for geometrical errors and energy stability check. Further, a molecular docking analysis was carried out against quercetin and its analogues and the docked analogues were accessed for ADME–toxicity parameters. ResultsThe three-dimensional structure of iNOS of G. gallus was generated and the assessment analysis revealed the generated model is reliable. The molecular docking and ADME–toxicity analysis revealed three analogues have favourable interaction energy with enhanced pharmacological parameters than quercetin at the binding cavity of iNOS enzyme. ConclusionThe analogues of quercetin could be a lead molecule and supports for experimental testing as iNOS inhibitors in fighting against cancer.

An ancient immunity gene duplication in Daphnia magna: RNA expression and sequence analysis of two nitric oxide synthase genes

NO (nitric oxide) is a highly reactive free radical gas thought to play a major role in the invertebrate immune response by harming pathogens and limiting their growth. Here we report on studies of nitric oxide synthase (NOS) genes in the crustacean Daphnia, one of the few non-insect arthropod models used to study host–pathogen interactions. While the NOS gene is found as a single copy in other invertebrates, we found two copies (NOS1 and NOS2), which a phylogenetic reconstruction showed to be the result of an ancient duplication event. Both genes bear features commonly found in invertebrate NOS, however, the two genes differ in their rate of evolution, intraspecific polymorphism and expression level. We tested whether the more rapid evolution of NOS2 could be due to positive selection, but found the rate of amino-acid substitutions between Daphnia species to be compatible with a neutral model. To associate NOS or NO activity with infection, we performed infection experiments with Daphnia magna and one of its natural pathogens (the bacterium Pasteuria ramosa). In one set of experimental infections, we supplemented D. magna with l-arginine, the NOS substrate, or with l-NAME, a NOS antagonist, and found this to result in lower and higher infection levels, respectively, which is at least compatible with the notion that NO may aid defence against Pasteuria. A second experiment indicated that NOS transcription does not increase following exposure to Pasteuria. Thus, the function of NOS in Daphnia immunity remains uncertain, but the pattern of gene duplication and subsequent divergence suggests evolution via neo- or subfunctionalization.

Visualizing inducible nitric-oxide synthase in living cells with a heme-binding fluorescent inhibitor

The study of nitric-oxide synthase (NOS) physiology is constrained by the lack of suitable probes to detect NOS in living cells or animals. Here, we characterized a fluorescent inducible NOS (iNOS) inhibitor called PIF (pyrimidine imidazole FITC) and examined its utility for microscopic imaging of iNOS in living cells. PIF binding to iNOS displayed high affinity, isoform selectivity, and heme specificity, and was essentially irreversible. PIF was used to successfully image iNOS expressed in RAW264.7 cells, HEK293T cells, human A549 epithelial cells, and freshly obtained human lung epithelium. PIF was used to estimate a half-life for iNOS of 1.8 h in HEK293T cells. Our work reveals that fluorescent probes like PIF will be valuable for studying iNOS cell biology and in understanding the pathophysiology of diseases that involve dysfunctional iNOS expression.

Immunohystochemical study of nitric oxide synthase's (NOS) activity in IBD colonic mucosa

Immunohystochemical study of nitric oxide synthase's (NOS) activity in IBD colonic mucosa

A new decoration for nitric oxide synthase - a Zn(Cys)4 site.

Intense interest in the action and synthesis of nitric oxide has fueled structural studies of nitric oxide synthase (NOS). The monomeric and dimeric heme domains of inducible NOS were the first NOS structures to be described. A recent independent analysis of the corresponding heme domains from endothelial NOS confirms most of the features found earlier and also reveals a novel Zn(Cys)4 center - a new feature for NOS.

CO binding studies of nitric oxide synthase: effects of the substrate, inhibitors and tetrahydrobiopterin

The dissociation constant ( K d) for CO from neuronal nitric oxide synthase heme in the absence of the substrate and cofactor was less than 10 −3 μM. In the presence of l-Arg, it dramatically increased up to 1 μM. In the presence of inhibitors such as N G-nitro- l-arginine methyl ester and 7-nitroindazole (NI), the K d value further increased up to more than 100 μM. Addition of the cofactor, 5,6,7,8-tetrahydrobiopterin (H 4B), increased the K d value by 10-fold in the presence of l-Arg, whereas it decreased the value to less than one 250th in the presence of NI. Addition of H 4B increased the recombination rate constant ( k on) for CO by more than two-fold in the presence of l-Arg or N 6-(1-iminoethyl)- l-lysine, whereas it decreased the k on value by three-fold in the presence of l-thiocitrulline. Thus, the binding fashion of some of inhibitors, such as NI, may be different from that of l-Arg with respect to the H 4B effect.

Localization and actions of nitric oxide in the cat carotid body

An extensive plexus of nerve fibers capable of synthesizing nitric oxide was demonstrated in the cat carotid body by immunocytochemical and biochemical studies of nitric oxide synthase. Denervation experiments indicated that the axons originate from: (i) microganglial neurons located within the carotid body and along the glossopharyngeal and carotid sinus nerves, whose ramifications primarily innervate carotid body blood vessels. (ii) sensory neurons in the petrosal ganglion, whose terminals end in association with lobules of type I cells. In the in vitro superfused cat carotid body, the nitric oxide synthase substrate, l-arginine, induced a dose-dependent inhibition of carotid sinus nerve discharge evoked by hypoxia. In contrast, the nitric oxide synthase inhibitor, l- N G-nitroarginine methylester, augmented the chemoreceptor response to hypoxia, and this effect was markedly enhanced when the preparation was both perfused and superfused in vitro. The nitric oxide donor, nitroglycerine, inhibited carotid sinus nerve discharge, and immunocytochemistry revealed that this drug stimulated the formation of cyclic 3', 5'-guanosine monophosphate in both type I cells and blood vessels. Our data indicate that nitric oxide is an inhibitory neuronal messenger in the carotid body, which affects the process of chemoreceptor transduction/transmission via actions on both the receptor elements and their associated blood vessels.

The Effect of Nonionic Detergents on the Activity and/or Stability of Rat Brain Nitric Oxide Synthase

The results of this study indicate that the addition of low concentrations of a nonionic detergent such as those represented by the Tween, Brij, or Triton classes causes an apparent activation of nitric oxide synthase. It is possible that this apparent activation is due to the ability of these detergents to stabilize the protein. The stabilizing influence of the detergents may be a result of inhibiting the dissociation of the dimeric protein into monomers or the dissociation of an essential cofactor or prosthetic group from the active enzyme. Regardless of the mechanism of action, the addition of low concentrations of nonionic detergents results in longer and increased nitric oxide synthase activity and may be an important tool for those involved in enzymological studies of nitric oxide synthase.