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Queuine
Queuine () (Q) is a hypermodified nucleobase found in the first (or wobble) position of the anticodon of tRNAs specific for Asn, Asp, His, and Tyr, in most eukaryotes and prokaryotes. Because it is utilized by all eukaryotes but produced exclusively by bacteria, it is a putative vitamin. The nucleoside of queuine is queuosine. Queuine is not found in the tRNA of archaea; however, a related 7-deazaguanine derivative, the nucleoside of which is archaeosine, occurs in different tRNA position, the dihydrouridine loop, and in tRNAs with more specificities. History and naming In 1967, it was discovered that the four above-mentioned tRNAs contained an as-yet unknown nucleoside, which was designated "Nucleoside Q". This name remained in use throughout much of the work to characterize the compound, after which it was proposed that its common name should be based on the sound of the letter Q—thus producing "queuine" by analogy to guanine and other nucleobases, and "queuosine" by analog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeosine
Archaeosine (G*) is a modified nucleoside found in the dihydrouracil loop at position 15 of tRNAs found in Archaea, and is thought to be important for the heat resistance of thermophilic archaea such as ''Thermococcus kodakarensis''. See also * Queuine Queuine () (Q) is a hypermodified nucleobase found in the first (or wobble) position of the anticodon of tRNAs specific for Asn, Asp, His, and Tyr, in most eukaryotes and prokaryotes. Because it is utilized by all eukaryotes but produced exclusiv ... References {{reflist Nucleosides Hydroxymethyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleobase
Nucleobases, also known as ''nitrogenous bases'' or often simply ''bases'', are nitrogen-containing biological compounds that form nucleosides, which, in turn, are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids. The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Five nucleobases—adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U)—are called ''primary'' or ''canonical''. They function as the fundamental units of the genetic code, with the bases A, G, C, and T being found in DNA while A, G, C, and U are found in RNA. Thymine and uracil are distinguished by merely the presence or absence of a methyl group on the fifth carbon (C5) of these heterocyclic six-membered rings. In addition, some viruses have aminoadenine (Z) instead of adenine. It differs in having an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biopterin-dependent Aromatic Amino Acid Hydroxylase
Biopterin-dependent aromatic amino acid hydroxylases (AAAH) are a family of aromatic amino acid hydroxylase enzymes which includes phenylalanine 4-hydroxylase (), tyrosine 3-hydroxylase (), and tryptophan 5-hydroxylase (). These enzymes primarily hydroxylate the amino acids L-phenylalanine, L-tyrosine, and L-tryptophan, respectively. The AAAH enzymes are functionally and structurally related proteins which act as rate-limiting catalysts for important metabolic pathways. Each AAAH enzyme contains iron and catalyzes the ring hydroxylation of aromatic amino acids using tetrahydrobiopterin (BH4) as a substrate. The AAAH enzymes are regulated by phosphorylation at serines in their N-termini. Role in metabolism In humans, phenylalanine hydroxylase deficiency can cause phenylketonuria, the most common inborn error of amino acid metabolism. Phenylalanine hydroxylase catalyzes the conversion of to . Tyrosine hydroxylase catalyzes the rate-limiting step in catecholamine biosynthesis: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleobases
Nucleobases, also known as ''nitrogenous bases'' or often simply ''bases'', are nitrogen-containing biological compounds that form nucleosides, which, in turn, are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids. The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Five nucleobases—adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U)—are called ''primary'' or ''canonical''. They function as the fundamental units of the genetic code, with the bases A, G, C, and T being found in DNA while A, G, C, and U are found in RNA. Thymine and uracil are distinguished by merely the presence or absence of a methyl group on the fifth carbon (C5) of these heterocyclic six-membered rings. In addition, some viruses have aminoadenine (Z) instead of adenine. It differs in having an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adrenaline
Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and by a small number of neurons in the medulla oblongata. It plays an essential role in the fight-or-flight response by increasing blood flow to muscles, heart output by acting on the SA node, pupil dilation response, and blood sugar level. It does this by binding to alpha and beta receptors. It is found in many animals, including humans, and some single-celled organisms. It has also been isolated from the plant ''Scoparia dulcis'' found in Northern Vietnam. Medical uses As a medication, it is used to treat several conditions, including allergic reaction anaphylaxis, cardiac arrest, and superficial bleeding. Inhaled adrenaline may be used to improve the symptoms of croup. It may also be used for asthma when other treatments are not eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norepinephrine
Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', "near", and '' ren'', "kidney") is more commonly used in the United Kingdom, whereas "norepinephrine" (from Ancient Greek ἐπῐ́ (''epí''), "upon", and νεφρός (''nephrós''), "kidney") is usually preferred in the United States. "Norepinephrine" is also the international nonproprietary name given to the drug. Regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as noradrenergic. The general function of norepinephrine is to mobilize the brain and body for action. Norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response. In the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melatonin
Melatonin is a natural product found in plants and animals. It is primarily known in animals as a hormone released by the pineal gland in the brain at night, and has long been associated with control of the sleep–wake cycle. In vertebrates, melatonin is involved in synchronizing circadian rhythms, including sleep–wake timing and blood pressure regulation, and in control of seasonal rhythmicity including reproduction, fattening, moulting and hibernation. Many of its effects are through activation of the melatonin receptors, while others are due to its role as an antioxidant. In plants, it functions to defend against oxidative stress. It is also present in various foods. Melatonin was discovered in 1958. In addition to its role as a natural hormone, melatonin is used as a dietary supplement and medication in the treatment of sleep disorders such as insomnia and circadian rhythm sleep disorders; for information on melatonin as a supplement and medication, see the melatoni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 80% of the catecholamine content in the brain. It is an amine synthesized by removing a carboxyl group from a molecule of its precursor (chemistry), precursor chemical, L-DOPA, which is biosynthesis, synthesized in the brain and kidneys. Dopamine is also synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. Neurotransmitters are synthesized in specific regions of the brain, but affect many regions systemically. The brain includes several distinct dopaminergic pathway, dopamine pathways, one of which plays a major role in the motivational component of reward system, reward-motivated behavior. The anticipa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction. Approximately 90% of the serotonin that the body produces is in the intestinal tract. Biochemically, the indoleamine molecule derives from the amino acid tryptophan, via the (rate-limiting) hydroxylation of the 5 position on the ring (forming the intermediate 5-hydroxytryptophan), and then decarboxylation to produce serotonin. Serotonin is primarily found in the enteric nervous system located in the gastrointestinal tract (GI tract). However, it is also produced in the central nervous system (CNS), specifically in the raphe nuclei located in the brainstem, Merkel cells located in the skin, pulmonary neuroendocrine cells and taste receptor cells in the tongue. Additionally, serotonin is stored in blood platelets and is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydropteridine Reductase
In enzymology, 6,7-dihydropteridine reductase (, also Dihydrobiopterin reductase) is an enzyme that catalyzes the chemical reaction : 5,6,7,8-tetrahydropteridine + NAD(P)+ \rightleftharpoons 6,7-dihydropteridine + NAD(P)H + H+ The four substrates for this enzyme are a 6,7-dihydropteridine ( dihydrobiopterin), NADH, NADPH, and H+ and its three products are 5,6,7,8-tetrahydropteridine ( tetrahydrobiopterin), NAD+, and NADP+ This enzyme participates in folate biosynthesis. In the human genome, the enzyme is encoded by the QDPR gene. Nomenclature This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 5,6,7,8-tetrahydropteridine:NAD(P)+ oxidoreductase. Other names in common use include 6,7-dihydropteridine:NAD(P)H oxidoreductase, DHPR, NAD(P)H:6,7-dihydropteridine oxidoreductase, NADH-dihydropteridine reductase, NADPH-dihydropteridine reductase, NA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydrobiopterin
Dihydrobiopterin (BH2) is a pteridine compound produced in the synthesis of L-DOPA, dopamine, serotonin, norepinephrine and epinephrine. It is restored to the required cofactor tetrahydrobiopterin by dihydrobiopterin reductase. See also * Pteridine * Tetrahydrobiopterin Tetrahydrobiopterin (BH4, THB), also known as sapropterin (INN), is a cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotoni ... Biomolecules {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5-HTP
5-Hydroxytryptophan (5-HTP), also known as oxitriptan, is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitter serotonin. Uses 5-HTP is sold over the counter in the United States, Canada, Singapore, the Netherlands, and the United Kingdom as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid. It is also marketed in many European countries for the indication of major depression under the trade names Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum. A 2002 review concluded that although the data evaluated suggests that 5-HTP is more effective than placebo in the treatment of depression, the evidence was insufficient to be conclusive due to a lack of clinical data meeting the rigorous standards of the day. More and larger studies using current methodologies are needed to determine if 5-HTP is truly effective in treating depression. In small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
