数据之源，洞见之始

The amino acid betaine derived from glycine." []

2-Amino-3-methylbutanoic acid

Valine (Val) or L-valine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. L-valine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Valine is found in all organisms ranging from bacteria to plants to animals. It is classified as a non-polar, uncharged (at physiological pH) aliphatic amino acid. Valine was first isolated from casein in 1901 by Hermann Emil Fischer. The name valine comes from valeric acid, which in turn is named after the plant valerian due to the presence of valine in the roots of the plant. Valine is essential in humans, meaning the body cannot synthesize it, and it must be obtained from the diet. Human dietary sources are foods that contain protein, such as meats, dairy products, soy products, beans and legumes. L-valine is a branched chain amino acid (BCAA). The BCAAs consist of leucine, valine and isoleucine (and occasionally threonine). BCAAs are essential amino acids whose carbon structure is marked by a branch point at the beta-carbon position. BCAAs are critical to human life and are particularly involved in stress, energy and muscle metabolism. BCAA supplementation as therapy, both oral and intravenous, in human health and disease holds great promise. BCAAs have different metabolic routes, with valine going solely to carbohydrates (glucogenic), leucine solely to fats (ketogenic) and isoleucine being both a glucogenic and a ketogenic amino acid. The different metabolism accounts for different requirements for these essential amino acids in humans: 12 mg/kg, 14 mg/kg and 16 mg/kg of valine, leucine and isoleucine respectively. Like other branched-chain amino acids, the catabolism of valine starts with the removal of the amino group by transamination, giving alpha-ketoisovalerate, an alpha-keto acid, which is converted to isobutyryl-CoA through oxidative decarboxylation by the branched-chain α-ketoacid dehydrogenase complex. This is further oxidised and rearranged to succinyl-CoA, which can enter the citric acid cycle. Furthermore, these amino acids have different deficiency symptoms. Valine deficiency is marked by neurological defects in the brain, while isoleucine deficiency is marked by muscle tremors. Many types of inborn errors of BCAA metabolism exist, and are marked by various abnormalities. The most common form is the maple syrup urine disease, marked by a characteristic urinary odor. Other abnormalities are associated with a wide range of symptoms, such as mental retardation, ataxia, hypoglycemia, spinal muscle atrophy, rash, vomiting and excessive muscle movement. Most forms of BCAA metabolism errors are corrected by dietary restriction of BCAA and at least one form is correctable by supplementation with 10 mg of biotin daily. BCAA are decreased in patients with liver disease, such as hepatitis, hepatic coma, cirrhosis, extrahepatic biliary atresia or portacaval shunt. Valine in particular, has been established as a useful supplemental therapy to the ailing liver. Valine, like other branched-chain amino acids, is associated with insulin resistance: higher levels of valine are observed in the blood of diabetic mice, rats, and humans (PMID: 25287287). Mice fed a valine deprivation diet for one day have improved insulin sensitivity and feeding of a valine deprivation diet for one week significantly decreases blood glucose levels (PMID: 24684822). In diet-induced obese and insulin resistant mice, a diet with decreased levels of valine and the other branched-chain amino acids results in reduced adiposity and improved insulin sensitivity (PMID: 29266268). In sickle-cell disease, valine substitutes for the hydrophilic amino acid glutamic acid in hemoglobin. Because valine is hydrophobic, the hemoglobin does not fold correctly. Hypervalinemia is another example of an inborn error of metabolism involving valine.

Norvaline is a non-proteinogenic branched-chain amino acid with the chemical formula C5H11NO2, isomeric with valine. It has previously been reported to be a natural component of an antifungal peptide of Bacillus subtilis. Norvaline and other modified branched chain amino acids have received attention in recent studies, as they appear to be incorporated in some recombinant proteins found in E. coli. This amino acid is often made synthetically.

2S-amino-pentanoic acid

N-Methyl-a-aminoisobutyric acid, also known as 2-(methylamino)isobutyrate or AMAIB, belongs to the class of organic compounds known as alpha amino acids. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). N-Methyl-a-aminoisobutyric acid is a drug. N-Methyl-a-aminoisobutyric acid is a metabolite that is actively incorporated into the cell by the actions of Interleukin 1-beta and Interleukin 6 via sodium dependent transport systems (PMID 16202926).

5-Aminopentanoic acid (or 5-aminovalerate) is a lysine degradation product. It can be produced both endogenously or through bacterial catabolism of lysine. 5-aminovalerate is formed via the following multi-step reaction: L-lysine leads to cadverine leads to L-piperideine leads 5-aminovalerate (PMID:405455). In other words it is a metabolite of cadaverine which is formed via the intermediate, 1-piperideine (PMID:6436440). Cadaverine is a foul-smelling diamine compound produced by protein hydrolysis during putrefaction of animal tissue. High levels of 5-aminovalerate in biofluids may indicate bacterial overgrowth or endogenous tissue necrosis. In most cases endogenous 5-aminovalerate is thought to be primarily a microbial metabolite produced by the gut or oral microflora, although it can be produced endogenously. 5-aminovalerate is a normal metabolite present in human saliva, with a tendency to elevated concentration in patients with chronic periodontitis. Bacterial contamination and decomposition of salivary proteins is primarily responsible for elevated salivary levels (PMID 3481959). Beyond being a general waste product, 5-aminovalerate is also believed to act as a methylene homologue of gamma-aminobutyric acid (GABA) and functions as a weak GABA agonist (PMID:4031870). It is also known as an antifibrinolytic amino acid analog and so it functions as a weak inhibitor of the blood clotting pathway (PMID:6703712). 5- aminovalerate is an in vivo substrate of 4-aminobutyrate:2-oxoglutarate aminotransferase (PMID:4031870). It can be found in Corynebacterium (PMID:27717386).

Isoamyl nitrite (IAN) has been used as antianginal agents for more than 100 years. It is now established that IAN cause direct vasorelaxation through vascular generation of NO and relaxation via a cyclic guanosine monophosphate-dependent process. (PMID: 8996213). IAN is a member of the family of volatile organic nitrites that exert vasodilatory effects and have recently exhibited a considerable potential for inhalation abuse. (PMID: 9829558). All nitrovasodilators act intracellularly by a common molecular mechanism. This is characterized by the release of nitric oxide (NO). This process basically depends on the presence of oxygen as electron acceptor from the sydnonimine molecule. Organic nitrites (such as IAN) require the interaction with a mercapto group to form a S-nitrosothiol intermediate, from which finally NO radicals are liberated. In the presence of thiol compounds organic nitrites (e.g., IAN) and nitrosothiols may act as intermediary products of NO generation. (PMID: 1683227).

4-amino-pentanoic acid

Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. The participation of the nitrogen lone electron pair in the aromatic ring means that indole is not a base, and it does not behave like a simple amine. Indole is a microbial metabolite and it can be produced by bacteria as a degradation product of the amino acid tryptophan. It occurs naturally in human feces and has an intense fecal smell. At very low concentrations, however, indole has a flowery smell and is a constituent of many flower scents (such as orange blossoms) and perfumes. As a volatile organic compound, indole has been identified as a fecal biomarker of Clostridium difficile infection (PMID: 30986230). Natural jasmine oil, used in the perfume industry, contains around 2.5% of indole. Indole also occurs in coal tar. Indole has been found to be produced in a number of bacterial genera including Alcaligenes, Aspergillus, Escherichia, and Pseudomonas (PMID: 23194589, 2310183, 9680309). Indole plays a role in bacterial biofilm formation, bacterial motility, bacterial virulence, plasmid stability, and antibiotic resistance. It also functions as an intercellular signalling molecule (PMID: 26115989). Recently, it was determined that the bacterial membrane-bound histidine sensor kinase (HK) known as CpxA acts as a bacterial indole sensor to facilitate signalling (PMID: 31164470). It has been found that decreased indole concentrations in the gut promote bacterial pathogenesis, while increased levels of indole in the gut decrease bacterial virulence gene expression (PMID: 31164470). As a result, enteric pathogens sense a gradient of indole concentrations in the gut to migrate to different niches and successfully establish an infection.

A morpholine N-oxide resulting from the oxidation of the amino group of N-methylmorpholine." []

Major species at pH 7.3. Published in DOI:10.1039/C6CY01625A" []

The simplest member of the class of delta-lactone that is tetrahydro-2H-pyran substituted by an oxo group at position 2." []

Benzeneacetonitrile is found in garden cress. Benzeneacetonitrile is isolated from oil of garden cress (Lepidium sativum) and other plant oils.

L-allothreonine is the L-enantiomer of allothreonine. It has a role as an Escherichia coli metabolite and a Saccharomyces cerevisiae metabolite. It is an enantiomer of a D-allothreonine. It is a tautomer of a L-allothreonine zwitterion. Allothreonine is the substrate of the enzyme Serine hydroxymethyltransferase1 (SHMT, EC 2.1.2.1), a human cytoplasmic mRNA binding protein. SHMT uses pyridoxal 5'-phosphate (PLP) and tetrahydropteroylglutamate (H4PteGlu) as coenzymes and catalyzes the reversible interconversion of serine and glycine. In addition to these physiological reactions, SHMT also catalyzes, in the absence of H4PteGlu, the retroaldol cleavage of several 3-hydroxyamino acids, such as allothreonine. Allothreonine is a plant metabolite that appears in the human diet in variable concentrations depending on: plant species, physiological changes during plant growth, senescence, and reactions to environmental stress or to changes due to plant transformation (PMID:10858298, 10952545).

2-Aminoacetophenone is found in cereals and cereal products. 2-Aminoacetophenone is a component of tortilla aroma and of other corn flour product

An optically active form of threonine having D-configuration." []

2-aminopentanoic acid is an alpha-amino acid that is valeric acid which is substituted at position 2 by an amino group. It is functionally related to a valeric acid. DL-Norvaline is a natural product found in Arabidopsis thaliana and Aeromonas veronii with data available.

An alpha-amino acid in which one of the hydrogens attached to the alpha-carbon of glycine is substituted by a 1-hydroxyethyl group." []

Betaine (CAS: 107-43-7), also known as N,N,N-trimethylglycine, was named after its discovery in sugar beet (Beta vulgaris) in the 19th century. It is a small N-trimethylated amino acid, existing in zwitterionic form at neutral pH. It is now often called glycine betaine to distinguish it from other betaines that are widely distributed in microorganisms, plants, and animals. Many naturally occurring betaines serve as organic osmolytes, substances synthesized or taken up from the environment by cells for protection against osmotic stress, drought, high salinity, or high temperature. Intracellular accumulation of betaines permits water retention in cells, thus protecting from the effects of dehydration (Wikipedia). Betaine functions as a methyl donor in that it carries and donates methyl functional groups to facilitate necessary chemical processes. In particular, it methylates homocysteine to methionine, also producing N,N-dimethylglycine. The donation of methyl groups is important to proper liver function, cellular replication, and detoxification reactions. Betaine also plays a role in the manufacture of carnitine and serves to protect the kidneys from damage. Betaine comes from either the diet or by the oxidation of choline. Betaine insufficiency is associated with metabolic syndrome, lipid disorders, and diabetes, and may have a role in vascular and other diseases (PMID: 20346934). Betaine is important in development, from the pre-implantation embryo to infancy. Betaine is also widely regarded as an anti-oxidant. Betaine has been shown to have an inhibitory effect on NO release in activated microglial cells and may be an effective therapeutic component to control neurological disorders (PMID: 22801281). As a drug, betaine hydrochloride has been used as a source of hydrochloric acid in the treatment of hypochlorhydria. Betaine has also been used in the treatment of liver disorders, for hyperkalemia, for homocystinuria, and for gastrointestinal disturbances (Martindale, The Extra Pharmacopoeia, 30th Ed, p1341).

1-Amino-4-ethynylbenzene http://www.sigmaaldrich.com/catalog/search/ProductDetail/FLUKA/46039

4R-aminopentanoic acid

4S-aminopentanoic acid

2H-isoindole is an isoindole and a polycyclic heteroarene. It is a tautomer of a 1H-isoindole. Benzopyrroles with the nitrogen at the number two carbon, in contrast to INDOLES which have the nitrogen adjacent to the six-membered ring.

Ethyl acrylate is an organic compound with the formula CH2CHCO2CH2CH3. It is the ethyl ester of acrylic acid. It is a colourless liquid with a characteristic acrid odor. Ethyl acrylate is found in pineapple. Ethyl acrylate is a flavouring ingredient Although there are some reports claiming that ethyl acrylate is a carcinogen, major respected bodies regard the evidence of human carcinogenicity as weak and/or inconsistent. The International Agency for Research on Cancer stated, "Overall evaluation, Ethyl acrylate is possibly carcinogenic to humans (Group 2B)." The United States Environmental Protection Agency (EPA) states, "Human studies on occupational exposure to ethyl acrylate have suggested a relationship between exposure to the chemical(s) and colorectal cancer, but the evidence is conflicting and inconclusive. In a study by the National Toxicology Program (NTP), increased incidences of squamous cell papillomas and carcinomas of the forestomach were observed in rats and mice exposed via gavage (experimentally placing the chemical in the stomach). However, the NTP recently determined that these data were not relevant to human carcinogenicity and removed ethyl acrylate from its list of carcinogens." (Occupational exposure generally involves exposure that occurs regularly, over an extended period of time). Ethyl acrylate is an organic compound primarily used in the preparation of various polymers. It is a clear liquid with an acrid penetrating odor. The human nose is capable of detecting this odor at a thousand times lower concentration then is considered harmful if continuously exposed for some period of time.

3-Aminopropanal is a reactive aldehyde that mediates progressive neuronal necrosis and glial apoptosis. (PMID 11943872). Increased activity of polyamine oxidase catabolizes polyamines (such as spermine, spermidine and putrescine) to produce 3-aminopropanal. (PMID 15246852).

Hydroxyethyl glycine is a metabolite of linezolid. Linezolid is a synthetic antibiotic used for the treatment of serious infections caused by Gram-positive bacteria that are resistant to several other antibiotics. A member of the oxazolidinone class of drugs, linezolid is active against most Gram-positive bacteria that cause disease, including streptococci, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA). (Wikipedia)

4-Amino-3-hydroxybutyrate belongs to the class of organic compounds known as hydroxy fatty acids. These are fatty acids in which the chain bears a hydroxyl group.