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Kynurenine
-Kynurenine is a metabolite of the amino acid -tryptophan used in the production of niacin. Kynurenine is synthesized by the enzyme tryptophan dioxygenase, which is made primarily but not exclusively in the liver, and indoleamine 2,3-dioxygenase, which is made in many tissues in response to immune activation. Kynurenine and its further breakdown products carry out diverse biological functions, including dilating blood vessels during inflammation and regulating the immune response. Some cancers increase kynurenine production, which increases tumor growth. Evidence suggests that increased kynurenine production may precipitate depressive symptoms associated with interferon treatment for hepatitis C. Cognitive deficits in schizophrenia are associated with imbalances in the enzymes that break down kynurenine. Blood levels of kynurenine are reduced in people with bipolar disorder. Kynurenine production is increased in Alzheimer's disease and cardiovascular disease where its metabolit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynurenine 3-hydroxylase
In enzymology, a kynurenine 3-monooxygenase () is an enzyme that catalyzes the chemical reaction : -kynurenine + NADPH + H+ + O2 3-hydroxy--kynurenine + NADP+ + H2O Kynurenine 3-monooxygenase is the expression product of the KMO (gene). The systematic name of this enzyme class is -kynurenine, NADPH:oxygen oxidoreductase (3-hydroxylating). Other names in common use include kynurenine 3-hydroxylase, kynurenine hydroxylase, and -kynurenine-3-hydroxylase. It participates in tryptophan metabolism through the kynurenine catabolic pathway. This enzyme belongs to the family of oxidoreductases, to be specific, those acting on paired donors, with O2 as the oxidant. Kynurenine 3-monooxygenase catalyzes the insertion of molecular oxygen into the aromatic ring of kynurenine to produce 3-hydroxy--kynurenine. It employs one cofactor, FAD. Kynurenine 3-monooxygenase serves as an important branch point in the kynurenine pathway and, as a result, is an attractive drug target for immunolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynurenine Pathway
400px, The kynurenine pathway The kynurenine pathway is a metabolic pathway leading to the production of nicotinamide adenine dinucleotide (NAD+). Metabolites involved in the kynurenine pathway include tryptophan, kynurenine, kynurenic acid, xanthurenic acid, quinolinic acid, and 3-hydroxykynurenine. The kynurenine pathway is responsible for total catabolization of tryptophan about 95%. Disruption in the pathway is associated with certain genetic and psychiatric disorders. Kynurenine pathway dysfunction Disorders affecting the kynurenine pathway may be primary (of genetic origin) or secondary (due to inflammatory conditions). Peripheral inflammation can lead to a build up of kynurenine in the brain, and this is associated with major depressive disorder, bipolar disorder, and schizophrenia. Dysfunction of the pathway not only cause increasing metabolites such as quinolinic acid or kynurenic acid but also affects serotonin and melatonin synthesis. Kynurenine clearance in exerc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynurenine Pathway Wordless
-Kynurenine is a metabolite of the amino acid -tryptophan used in the production of niacin. Kynurenine is synthesized by the enzyme tryptophan dioxygenase, which is made primarily but not exclusively in the liver, and indoleamine 2,3-dioxygenase, which is made in many tissues in response to immune activation. Kynurenine and its further breakdown products carry out diverse biological functions, including dilating blood vessels during inflammation and regulating the immune response. Some cancers increase kynurenine production, which increases tumor growth. Evidence suggests that increased kynurenine production may precipitate depressive symptoms associated with interferon treatment for hepatitis C. Cognitive deficits in schizophrenia are associated with imbalances in the enzymes that break down kynurenine. Blood levels of kynurenine are reduced in people with bipolar disorder. Kynurenine production is increased in Alzheimer's disease and cardiovascular disease where its metabolites ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quinolinic Acid
Quinolinic acid (abbreviated QUIN or QA), also known as pyridine-2,3-dicarboxylic acid, is a dicarboxylic acid with a pyridine backbone. It is a colorless solid. It is the biosynthetic precursor to niacin. Quinolinic acid is a downstream product of the kynurenine pathway, which metabolizes the amino acid tryptophan. It acts as an NMDA receptor agonist. Quinolinic acid has a potent neurotoxic effect. Studies have demonstrated that quinolinic acid may be involved in many psychiatric disorders, neurodegenerative processes in the brain, as well as other disorders. Within the brain, quinolinic acid is only produced by activated microglia and macrophages. History In 1949 L. Henderson was one of the earliest to describe quinolinic acid. Lapin followed up this research by demonstrating that quinolinic acid could induce convulsions when injected into mice brain ventricles. However, it was not until 1981 that Stone and Perkins showed that quinolinic acid activates the ''N''-methyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynurenic Acid
Kynurenic acid (KYNA or KYN) is a product of the normal metabolism of amino acid -tryptophan. It has been shown that kynurenic acid possesses neuroactive activity. It acts as an antiexcitotoxic and anticonvulsant, most likely through acting as an antagonist at excitatory amino acid receptors. Because of this activity, it may influence important neurophysiological and neuropathological processes. As a result, kynurenic acid has been considered for use in therapy in certain neurobiological disorders. Conversely, increased levels of kynurenic acid have also been linked to certain pathological conditions. Kynurenic acid was discovered in 1853 by the German chemist Justus von Liebig in dog urine, which it was apparently named after.Liebig, J., Uber Kynurensäure, ''Justus Liebigs Ann. Chem.'', 86: 125-126, 1853. It is formed from -kynurenine in a reaction catalyzed by the enzyme kynurenine—oxoglutarate transaminase. Mechanism of action KYNA has been proposed to act on five targe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tryptophan
Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic beta carbon substituent. It is essential in humans, meaning that the body cannot synthesize it and it must be obtained from the diet. Tryptophan is also a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3. It is encoded by the codon UGG. Like other amino acids, tryptophan is a zwitterion at physiological pH where the amino group is protonated (–; pKa = 9.39) and the carboxylic acid is deprotonated ( –COO−; pKa = 2.38). Humans and many animals cannot synthesize tryptophan: they need to obtain it through their diet, making it an essential amino acid. Function Amino acids, including tryptophan, are used as building blocks in protein biosynthesis, and proteins are required to sustain life. Man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynureninase
Kynureninase or L-Kynurenine hydrolase (KYNU) () is a PLP dependent enzyme that catalyses the cleavage of kynurenine (Kyn) into anthranilic acid (Ant). It can also act on 3-hydroxykynurenine (to produce 3-hydroxyanthranilate) and some other (3-arylcarbonyl)-alanines. Humans express one kynureninase enzyme that is encoded by the ''KYNU'' gene located on chromosome 2. KYNU is part of the pathway for the catabolism of Trp and the biosynthesis of NAD cofactors from tryptophan (Trp). Kynureninase catalyzes the following reaction: : L-kynurenine + H2O ↔ anthranilate + L-alanine Structure Kynureninase belongs to the class V group of aspartate aminotransferase superfamily of structurally homologous pyridoxal 5'-phosphate ( PLP) dependent enzymes. To date, two structures of human kynureninase have determined by X-ray diffraction with resolutions of 2.0 and 1.7 Å.; Forty percent of the amino acids are arranged in an alpha helical and twelve percent are arranged in beta sheets. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indoleamine 2,3-dioxygenase
Indoleamine-pyrrole 2,3-dioxygenase (IDO or INDO ) is a heme-containing enzyme physiologically expressed in a number of tissues and cells, such as the small intestine, lungs, female genital tract or placenta. In humans is encoded by the ''IDO1'' gene. IDO is involved in tryptophan metabolism. It is one of three enzymes that catalyze the first and rate-limiting step in the kynurenine pathway, the O2-dependent oxidation of L-tryptophan to N-formylkynurenine, the others being indolamine-2,3-dioxygenase 2 (IDO2) and tryptophan 2,3-dioxygenase (TDO). IDO is an important part of the immune system and plays a part in natural defense against various pathogens. It is produced by the cells in response to inflammation and has an immunosuppressive function because of its ability to limit T-cell function and engage mechanisms of immune tolerance. Emerging evidence suggests that IDO becomes activated during tumor development, helping malignant cells escape eradication by the immune system. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Misumena Vatia
''Misumena vatia'' is a species of crab spider with a holarctic distribution. In North America, it is called the goldenrod crab spider or flower (crab) spider,Acorn, John and Sheldon, Ian. (2003). ''Bugs of Ontario'' Edmonton: Lone Pine Publishing as it is commonly found hunting in goldenrod sprays and milkweed plants. They are called crab spiders because of their unique ability to walk sideways as well as forwards and backwards. Both males and females of this species progress through several molts before reaching their adult sizes, though females must molt more to reach their larger size. Females can grow up to while males are quite small, reaching at most. ''Misumena vatia'' are usually yellow or white or a pattern of these two colors. They may also present with pale green or pink instead of yellow, again, in a pattern with white. They have the ability to change between these colors based on their surroundings through the molting process. They have a complex visual system, wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anxiety Disorders
Anxiety disorders are a cluster of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal function are significantly impaired. Anxiety may cause physical and cognitive symptoms, such as restlessness, irritability, easy fatiguability, difficulty concentrating, increased heart rate, chest pain, abdominal pain, and a variety of other symptoms that may vary based on the individual. In casual discourse, the words ''anxiety'' and ''fear'' are often used interchangeably. In clinical usage, they have distinct meanings: anxiety is defined as an unpleasant emotional state for which the cause is either not readily identified or perceived to be uncontrollable or unavoidable, whereas fear is an emotional and physiological response to a recognized external threat. The umbrella term ''anxiety disorder'' refers to a number of specific disorders that include fears (phobias) or anxiety symptoms. There a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Sclerosis
Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This damage disrupts the ability of parts of the nervous system to transmit signals, resulting in a range of signs and symptoms, including physical, mental, and sometimes psychiatric problems. Specific symptoms can include double vision, blindness in one eye, muscle weakness, and trouble with sensation or coordination. MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms). In the relapsing forms of MS, between attacks, symptoms may disappear completely, although some permanent neurological problems often remain, especially as the disease advances. While the cause is unclear, the underlying mechanism is thought to be either destruction by the immune system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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