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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. Kynurenine protects the eye by absorbing UV light, especially in the UVA region (315–400 nm). Kynurenine is present in the lens and retina as one of multiple tryptophan derivatives produced in the eye, including 3-hydroxykynurenine, that together provide UV protection and aid in enhancing visual acuity. The use of kynurenine as a UV filter is consistent with its photostability and low photosensitization, owing to its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kynurenine 3-hydroxylase
In enzymology, a kynurenine 3-monooxygenase () is an enzyme that catalysis, catalyzes the chemical reaction :Kynurenine, -kynurenine + nicotinamide adenine dinucleotide phosphate, NADPH + hydrogen ion, H+ + oxygen, O2 3-Hydroxykynurenine, 3-hydroxy--kynurenine + nicotinamide adenine dinucleotide phosphate, NADP+ + water, H2O Kynurenine 3-monooxygenase is the expression product of the KMO (gene). The List of enzymes, 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 pathway, kynurenine catabolic pathway. This enzyme belongs to the family of oxidoreductases, to be specific, those acting on paired donors, with oxygen, O2 as the oxidant. Kynurenine 3-monooxygenase catalyzes the insertion of molecular oxygen into the aromatic ring of kynurenine to produce 3-h ... [...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. Kynurenine protects the eye by absorbing UV light, especially in the UVA region (315–400 nm). Kynurenine is present in the lens and retina as one of multiple tryptophan derivatives produced in the eye, including 3-hydroxykynurenine, that together provide UV protection and aid in enhancing visual acuity. The use of kynurenine as a UV filter is consistent with its photostability and low photosensitization, owing to its e ... [...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 about 95% of total tryptophan catabolism. 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 causes increase in amounts of metabolites such as quinolinic acid and kynurenic acid but also affects synthesis of serotonin and melatonin. Kynurenine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Hydroxykynurenine
3-Hydroxykynurenine is a metabolite of tryptophan, which filters UV light in the human lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') .... It is one of two pigments identified as responsible for the goldenrod crab spider's (''Misumena vatia)'' yellow coloration. 280px, left, The Kynurenine pathway, which connects quinolinic acid to tryptophan. The pathway is named for the first intermediate, kynurenine, which is a precursor to kynurenic acid and 3-hydroxykynurenine. References See also * Kynurenine * Ommochrome Aldehyde dehydrogenase inhibitors Alpha-Amino acids Phenols {{OrganicAcid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tryptophan Dioxygenase
In enzymology, tryptophan 2,3-dioxygenase () is a heme enzyme that catalyzes the oxidation of -tryptophan (-Trp) to ''N''-formyl--kynurenine, as the first and rate-limiting step of the kynurenine pathway. :-tryptophan + O2 ''N''-formyl--kynurenine Tryptophan 2,3-dioxygenase plays a central role in the physiological regulation of tryptophan flux in the human body, as part of the overall biological process of tryptophan metabolism. TDO catalyses the first and rate-limiting step of tryptophan degradation along the kynurenine pathway and thereby regulates systemic tryptophan levels. In humans, tryptophan 2,3-dioxygenase is encoded by the ''TDO2'' gene. Function This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). This family includes tryptophan 2,3-dioxygenase (TDO, also sometimes referred to as tryptophan oxygenase and -tryptophan pyrrolase) ... [...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] |
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 Tissue (biology), tissues and Cell (biology), 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, -tryptophan to N-formylkynurenine, ''N''-formylkynurenine, the others being Indoleamine 2,3-dioxygenase 2, indolamine-2,3-dioxygenase 2 (IDO2) and tryptophan 2,3-dioxygenase, 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 Immunosuppression, immunosuppressive function because of its ability to limit T-cell function and engage mechanisms of immune tolerance. ... [...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. Tryptophan is also a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3 (niacin). 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. Tryptophan is named after the digestive enzymes trypsin, which were used in its first isolation from casein proteins. It was assigned the one-letter symbol W based on the double ring being visually suggestive to the bulky letter. Function ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Major Depression
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introduced by a group of US clinicians in the mid-1970s, the term was adopted by the American Psychiatric Association for this symptom cluster under mood disorders in the 1980 version of the ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM-III), and has become widely used since. The disorder causes the second-most years lived with disability, after lower back pain. The diagnosis of major depressive disorder is based on the person's reported experiences, behavior reported by family or friends, and a mental status examination. There is no laboratory test for the disorder, but testing may be done to rule out physical conditions that can cause similar symptoms. The most common time of onset is in a person's 20s, with females affec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Misumena Vatia
''Misumena vatia'' is a species of crab spider found in Europe and North America. 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 Solidago, goldenrod sprays and Asclepias, 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 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
