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Biological Functions Of Nitric Oxide
Biological functions of nitric oxide are roles that nitric oxide plays within biology. Nitric oxide (nitrogen monoxide) is a molecule and chemical compound with chemical formula of N O. In mammals including humans, nitric oxide is a signaling molecule involved in several physiological and pathological processes. It is a powerful vasodilator with a half-life of a few seconds in the blood. Standard pharmaceuticals such as nitroglycerine and amyl nitrite are precursors to nitric oxide. Low levels of nitric oxide production are typically due to ischemic damage in the liver. As a consequence of its importance in neuroscience, physiology, and immunology, nitric oxide was proclaimed " Molecule of the Year" in 1992. Research into its function led to the 1998 Nobel Prize for elucidating the role of nitric oxide as a cardiovascular signalling molecule. Sources of nitric oxide Nitric oxide biosynthesis Platelet-derived factors, shear stress, acetylcholine, and cytokines stimulate the pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Oxide
Nitric oxide (nitrogen oxide, nitrogen monooxide, or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula (•N=O or •NO). Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding. An important intermediate in industrial chemistry, nitric oxide forms in combustion systems and can be generated by lightning in thunderstorms. In mammals, including humans, nitric oxide is a signaling molecule in many physiological and pathological processes. It was proclaimed the " Molecule of the Year" in 1992. The 1998 Nobel Prize in Physiology or Medicine was awarded for discovering nitric oxide's role as a cardiovascular signalling molecule. Its impact extends beyond biology, with applications in medicine, such as the development of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress or force per unit area is: \tau = ,where is the force applied and is the cross-sectional area. The area involved corresponds to the material face (geometry), face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:\tau_w := \mu\left.\frac\_,where is the dynamic viscosity, is the flow velocity, and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glyceryl Trinitrate (pharmacology)
Nitroglycerin, also known as glyceryl trinitrate (GTN), is a vasodilator used for heart failure, high blood pressure, anal fissures, painful periods, and to treat and prevent chest pain caused by decreased blood flow to the heart (angina) or due to the recreational use of cocaine. This includes chest pain from a heart attack. It is taken by mouth, under the tongue, applied to the skin, or by injection into a vein. Common side effects include headache and low blood pressure. The low blood pressure can be severe. It is unclear if use in pregnancy is safe for the fetus. It should not be used together with medications within the PDE5 inhibitor family such as sildenafil due to the risk of low blood pressure. Nitroglycerin is in the nitrate family of medications. While it is not entirely clear how it works, it is believed to function by dilating blood vessels. Nitroglycerin was written about as early as 1846 and came into medical use in 1878. The drug nitroglycerin is a dil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vasodilation
Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel walls are composed of endothelial tissue and a basal membrane lining the lumen of the vessel, concentric smooth muscle layers on top of endothelial tissue, and an adventitia over the smooth muscle layers. Relaxation of the smooth muscle layer allows the blood vessel to dilate, as it is held in a semi-constricted state by sympathetic nervous system activity. Vasodilation is the opposite of vasoconstriction, which is the narrowing of blood vessels. When blood vessels dilate, the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output. Vascular resistance is the amount of force circulating blood must overcome in order to allow perfusion of body tissues. Narrow vessels create more vascular resista ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene and are the result of genetic differences. While many perform the same or similar biological roles, some isoforms have unique functions. A set of protein isoforms may be formed from alternative splicings, variable promoter usage, or other post-transcriptional modifications of a single gene; post-translational modifications are generally not considered. (For that, see Proteoforms.) Through RNA splicing mechanisms, mRNA has the ability to select different protein-coding segments (exons) of a gene, or even different parts of exons from RNA to form different mRNA sequences. Each unique sequence produces a specific form of a protein. The discovery of isoforms could explain the discrepancy between the small number of protein coding regions of genes revealed by the human genome project and the large diversity of proteins seen in an organism: different proteins enc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Oxide Synthase
Nitric oxide synthases (NOSs) are a family of enzymes catalyzing the production of nitric oxide (NO) from L-arginine. NO is an important cellular signaling molecule. It helps modulate vascular tone, insulin secretion, airway tone, and peristalsis, and is involved in angiogenesis and neural development. It may function as a retrograde neurotransmitter. Nitric oxide is mediated in mammals by the calcium-calmodulin controlled isoenzymes eNOS (endothelial NOS) and nNOS (neuronal NOS). The inducible isoform, iNOS, involved in immune response, binds calmodulin at physiologically relevant concentrations, and produces NO as an immune defense mechanism, as NO is a free radical with an unpaired electron. It is the proximate cause of septic shock and may function in autoimmune disease. In the context of eukaryote biology, ''nitric oxide synthase'' refers to nitric-oxide synthase (NADPH) (), which catalyzes the reaction: * 2 L-arginine + 3 NADPH + 3 H+ + 4 O2 \rightleftharpoons 2 citrulli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calmodulin
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all Eukaryote, eukaryotic cells. It is an intracellular target of the Second messenger system, secondary messenger Calcium in biology, Ca2+, and the binding of Ca2+ is required for the activation of calmodulin. Once bound to Ca2+, calmodulin acts as part of a calcium Signal transduction, signal transduction pathway by modifying its interactions with various target proteins such as kinases or phosphatases. Structure Calmodulin is a small, highly conserved protein that is 148 amino acids long (16.7 kDa). The protein has two approximately symmetrical globular domains (the N- and C- domains) each containing a pair of EF hand Sequence motif, motifs separated by a flexible linker region for a total of four Ca2+ binding sites, two in each globular domain. In the Ca2+-free state, the helices that form the four EF-hands are collapsed in a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium
Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossils of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name comes from Latin ''calx'' " lime", which was obtained from heating limestone. Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharmaceuticals for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrulline
The organic compound citrulline is an α-amino acid. Its name is derived from '' citrullus'', the Latin word for watermelon. Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1914 by Japanese researchers Yatarō Koga (古賀彌太郎) and Ryō Ōtake (大嶽了) and further codified by Mitsunori Wada of Tokyo Imperial University in 1930. It has the formula H2NC(O)NH(CH2)3CH(NH2)CO2H. It is a key intermediate in the urea cycle, the pathway by which mammals excrete ammonia by converting it into urea. Citrulline is also produced as a byproduct of the enzymatic production of nitric oxide from the amino acid arginine, catalyzed by nitric oxide synthase. Biosynthesis Citrulline can be derived from: * from arginine via nitric oxide synthase, as a byproduct of the production of nitric oxide for signaling purposes * from ornithine through the breakdown of proline or glutamine/glutamate * from asymmetric dimet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L-arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the -arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of proteins. It is encoded by the codons CGU, CGC, CGA, CGG, AGA, and AGG. The guanidine group in arginine is the precursor for the biosynthesis of nitric oxide. Like all amino acids, it is a white, water-soluble solid. The one-letter symbol R was assigned to arginine for its phonetic similarity. History Arginine was first isolated in 1886 from yellow lupin seedlings by the German chemist Ernst Schulze and his assistant Ernst Steiger. He named it from the Greek ''árgyros'' (ἄργυρος) meaning "silver" due to the silver-white appearance of arginine nitrate crysta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanidine
Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experiencing renal failure. A guanidine moiety also appears in larger organic molecules, including on the side chain of arginine. Structure Guanidine can be thought of as a nitrogenous analogue of carbonic acid. That is, the C=O group in carbonic acid is replaced by a C=NH group, and each OH is replaced by a group. A detailed crystallographic analysis of guanidine was elucidated 148 years after its first synthesis, despite the simplicity of the molecule. In 2013, the positions of the hydrogen atoms and their displacement parameters were accurately determined using single-crystal neutron diffraction. Production Guanidine can be obtained from natural sources, being first isolated in 1861 by Adolph Strecker via the oxidative degradation of an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
