"of enzymes, with PDB accession codes , , , , , , , , , , , and . L-ascorbate peroxidase In enzymology, a L-ascorbate peroxidase () is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are L-ascorbate and HO, whereas its two products are dehydroascorbate and HO. This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is L-ascorbate:hydrogen-peroxide oxidoreductase. Other names in common use include L-ascorbic acid peroxidase, L-ascorbic acid-specific peroxidase, ascorbate peroxidase, and ascorbic acid peroxidase. This"
"had proven this, but published the result without giving Szent-Györgyi credit for it. This led to a bitter dispute over priority. In 1933, Walter Norman Haworth chemically identified the vitamin as -hexuronic acid, proving this by synthesis in 1933. Haworth and Szent-Györgyi proposed that L-hexuronic acid be named a-scorbic acid, and chemically -ascorbic acid, in honor of its activity against scurvy. The term's etymology is from Latin, ""a-"" meaning away, or off from, while -scorbic is from Medieval Latin ""scorbuticus"" (pertaining to scurvy), cognate with Old Norse ""skyrbjugr"", French ""scorbut"", Dutch ""scheurbuik"" and Low German ""scharbock"". Partly for this discovery,"
"the glutathione-ascorbate cycle, glutathione peroxidases and glutaredoxins, as well as reacting directly with oxidants. Due to its high concentration and its central role in maintaining the cell's redox state, glutathione is one of the most important cellular antioxidants. In some organisms glutathione is replaced by other thiols, such as by mycothiol in the Actinomycetes, bacillithiol in some Gram-positive bacteria, or by trypanothione in the Kinetoplastids. Vitamin E is the collective name for a set of eight related tocopherols and tocotrienols, which are fat-soluble vitamins with antioxidant properties. Of these, α-tocopherol has been most studied as it has the highest bioavailability,"
"while γ-tocopherol is the most common form in the American diet due to a higher intake of soybean and corn oil. Tocotrienols, which are related compounds, also have vitamin E activity. All of these various derivatives with vitamin activity may correctly be referred to as ""vitamin E"". Tocopherols and tocotrienols are fat-soluble antioxidants but also seem to have many other functions in the body. Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. All feature a chromane ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain"
"""Corynebacterium"", ""Flavobacterium"", ""Lactobacillus"", ""Micromonospora"", ""Mycobacterium"", ""Nocardia"", ""Protaminobacter"", ""Proteus"", ""Rhizobium"", ""Salmonella"", ""Serratia"", ""Streptococcus"" and ""Xanthomonas"" . Six Nobel Prizes have been awarded for direct and indirect studies of vitamin B. Vitamin B12 Vitamin B, also called cobalamin, is a water-soluble vitamin that is involved in the metabolism of every cell of the human body: it is a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is particularly important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the maturation of developing red blood cells in the"
"to infections and diseases. The National Research Council (NRC) suggested a ratio of vitamin E to polyunsaturated fatty acids be 0.6:1 to ensure enough vitamin E to combat any free radicals. Polyunsaturated fatty acids (PUFA) are prone to oxidative destruction in cellular membranes and increases the requirement for antioxidants. Vitamin C (ascorbic acid) is a water-soluble antioxidant and a free radical scavenger where it will donate an electron to compounds with unpaired elections or reactive but not radical compounds. Supplements of Vitamin C reduced oxidative DNA damage in cats prone to renal insufficiency, and can be beneficial to add into"
"1912 Casimir Funk coined the term vitamin to label a vital factor in the diet: from the words ""vital"" and ""amine,"" because these unknown substances preventing scurvy, beriberi, and pellagra, were thought then to derive from ammonia. The vitamins were studied in the first half of the 20th century. In 1913 Elmer McCollum discovered the first vitamins, fat-soluble vitamin A and water-soluble vitamin B (in 1915; later identified as a complex of several water-soluble vitamins) and named vitamin C as the then-unknown substance preventing scurvy. Lafayette Mendel (1872-1935) and Thomas Osborne (1859–1929) also performed pioneering work on vitamins A and"
"and do not require it in their diets. Ascorbic acid is required for the conversion of the procollagen to collagen by oxidizing proline residues to hydroxyproline. In other cells, it is maintained in its reduced form by reaction with glutathione, which can be catalysed by protein disulfide isomerase and glutaredoxins. Ascorbic acid is a redox catalyst which can reduce, and thereby neutralize, reactive oxygen species such as hydrogen peroxide. In addition to its direct antioxidant effects, ascorbic acid is also a substrate for the redox enzyme ascorbate peroxidase, a function that is particularly important in stress resistance in plants. Ascorbic"
"as ascorbic acid (vitamin C), polyphenols (including flavonoids), tocopherols, etc. A few of these appeared more recently, in the last 50–200 million years, in fruits and flowers of angiosperm plants. In fact, the angiosperms (the dominant type of plant today) and most of their antioxidant pigments evolved during the late Jurassic period. The deiodinase isoenzymes constitute another family of eukaryotic selenoproteins with identified enzyme function. Deiodinases are able to extract electrons from iodides, and iodides from iodothyronines. They are, thus, involved in thyroid-hormone regulation, participating in the protection of thyrocytes from damage by HO produced for thyroid-hormone biosynthesis. About 200"
"a necessary cofactor for the utilization of lysine in collagen synthesis. Collagen, the most abundant protein in the human body, requires great amounts of lysine, the most abundant amino acids in proteins. Ascorbic acid, the main hydroxyl radical quencher, works as the cofactor providing the hydroxyl radical required to collagen cross-linking; lysine thus becomes hydroxylysine. GA1 worsens during stresses and catabolic episodes, such as fasts and infections. Endogenous catabolism of proteins could be an important route for glutaric acid production. It thus follows that collagen breakdown (and protein breakdown in general) should be prevented by all possible means. Ascorbic acid"
"with the body preferentially absorbing and metabolising this form. It has been claimed that the α-tocopherol form is the most important lipid-soluble antioxidant, and that it protects membranes from oxidation by reacting with lipid radicals produced in the lipid peroxidation chain reaction. This removes the free radical intermediates and prevents the propagation reaction from continuing. This reaction produces oxidised α-tocopheroxyl radicals that can be recycled back to the active reduced form through reduction by other antioxidants, such as ascorbate, retinol or ubiquinol. This is in line with findings showing that α-tocopherol, but not water-soluble antioxidants, efficiently protects glutathione peroxidase 4"
"as an oral mucolytic and prophylactic agent against gingivitis. Ascoxal solution has also been tested with positive results as a treatment for recurrent mucocutaneous herpes, and as a mucolytic agent in acute and chronic pulmonary disease such as emphysema, bronchitis, and asthma by aerosol inhalation. Dehydroascorbic acid Dehydroascorbic acid (DHA) is an oxidized form of ascorbic acid (vitamin C). It is actively imported into the endoplasmic reticulum of cells via glucose transporters. It is trapped therein by reduction back to ascorbate by glutathione and other thiols. The (free) chemical radical semidehydroascorbic acid (SDA) also belongs to the group of oxidized"
"The activities and clinical significance of the EETs are given on the epoxyeicosatrienoic acid page. CYP2C9 and CYP2S1 are known to, and many or all of the other CYPs that act on arachidonic acid are thought to, metabolize the 18 carbon essential fatty acid, 9(""Z""),12(""Z"")-octadecadienoic acid, i.e. linoleic acid, at is 12,13 carbon-carbon double bout to form (+) and (-) epoxy optical isomers viz., the 9""S"",10""R""-epoxy-12(""Z"")-octadecaenoic and 9""R"",10""S""-epoxy-12(""Z"")-octadecaenoic acids; this set of optical isomers is also termed vernolic acid, linoleic acid 9:10-oxide, and leukotoxin. CYPC2C9 is known and the other arachidonic acid-metabolizing CYPs are thought to likewise attack linoleic acid"
"Experiments on linoleic acid subjected to 2,2'-Azobis(2-amidinopropane) dihydrochloride induced oxidation of linoleic acid; hence producing lipid radicals and then the use of different combinations of phenolics show that binary mixtures can lead to either a synergetic antioxidant effect or to an antagonistic effect towards the lipid radicals. Research like this is useful in discovering which phenols prevent the autoxidation of lipids in vegetable oils. Linoleic acid Linoleic acid (LA), a carboxylic acid, is a polyunsaturated omega-6 fatty acid, an 18-carbon chain with two double bonds in cis configuration. A shorthand notation like ""18:2 (n-6)"" or ""18:2 ""cis""-9,12"" may be used"
"only showed a lower nitrogen and higher phosphorus content in organic produced compared to conventionally grown foodstuffs. Content of vitamin C, calcium, potassium, total soluble solids, copper, iron, nitrates, manganese, and sodium did not differ between the two categories. A 2012 survey of the scientific literature did not find significant differences in the vitamin content of organic and conventional plant or animal products, and found that results varied from study to study. Produce studies reported on ascorbic acid (vitamin C) (31 studies), beta-carotene (a precursor for vitamin A) (12 studies), and alpha-tocopherol (a form of vitamin E) (5 studies) content;"
"as neurological disorders, inflammatory conditions, and depression. However, chronic unbalanced ingestion or high quantity supplementation could result in serious ailments due to the suppression of ROS. Allergies, asthma, bacterial and fungal infections of the skin (alterations) are known conditions that stem from antioxidant stress. There are many types of antioxidant compounds. Examples are, but not limited to, Carotenoids (Beta-carotene, Lycopene), Lutein, Manganese, Magnesium, Selenium, Vitamin A (retinol), Vitamin C (ascorbic acid, ascorbates), and Vitamin E (α‐Tocopherol, tocotrienols), and many more. These compounds can be found as ingredients in various products, or as components of ingredients, or as broader categorical classifications"
"cofactors include members of the vitamin B family. Vitamin B1 as thiamine diphosphate is a coenzyme for pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase, and transketolase which are all involved in carbohydrate metabolism. Vitamin B2 (riboflavin) is a constituent of FMN and FAD which are necessary for many redox reactions. Vitamin B3 (nicotinic acid or niacin), synthesized from tryptophan is a component of the coenzymes NAD and NADP which in turn are required for electron transport in the Krebs cycle, oxidative phosphorylation, as well as many other redox reactions. Vitamin B5 (pantothenic acid) is a constituent of coenzyme A, a basic component of"
"of methyl groups on the chromanol ring. All eight of these vitamers feature a chromane double ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals, and a hydrophobic side chain which allows for penetration into biological membranes. Of the many different forms of vitamin E, gamma-tocopherol (γ-tocopherol) is the most common form found in the North American diet, but alpha-tocopherol (α-tocopherol) is the most biologically active. Palm oil is a source of tocotrienols. Vitamin E was discovered in 1922, isolated in 1935 and first synthesized in 1938. Because the vitamin activity was first identified"
"due to differences in nuclear cataract rather than cortical or posterior subcapsular cataract - the three major classifications of age-related cataracts. However, this article and a second meta-analysis reporting on clinical trials of alpha-tocopherol supplementation reported no statistically significant change to risk of ARC when compared to placebo. Research on the effects of vitamin E on cardiovascular disease has produced conflicting results. In theory, oxidative modification of LDL-cholesterol promotes blockages in coronary arteries that lead to atherosclerosis and heart attacks, so vitamin E functioning as an antioxidant would reduce oxidized cholesterol and lower risk of cardiovascular disease. Vitamin E status"
"a number of mechanisms to minimize radical-induced damage and to repair damage that occurs, such as the enzymes superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. In addition, antioxidants play a key role in these defense mechanisms. These are often the three vitamins, vitamin A, vitamin C and vitamin E and polyphenol antioxidants. Furthermore, there is good evidence indicating that bilirubin and uric acid can act as antioxidants to help neutralize certain radicals. Bilirubin comes from the breakdown of red blood cells' contents, while uric acid is a breakdown product of purines. Too much bilirubin, though, can lead to jaundice,"
"and sun exposure can greatly affect lipid and pigment composition. As more is learned about the components of different cyanobacterial species, growers and harvesters are better able to determine the optimal growth conditions for obtaining optimal yields. "" Aphanizomenon flos-aquae"" has been shown to contain varying amounts at least 13 vitamins: vitamin A (beta-carotene), vitamin C (ascorbic acid), vitamin E, vitamin K, and many of the B-complex vitamins including B (thiamin), B (riboflavin), B (pyridoxine), choline, biotin, niacin, folic acid, pantothenic acid, and B (cobalamin). However, ""Aphanizomenon flos-aquae"" contains pseudovitamin B which can block absorbtion of true B and is"
"biochemical point of view, two essential enzymatic reactions require vitamin B (cobalamin). Intracellular vitamin B is maintained in two active coenzymes, methylcobalamin and 5-deoxyadenosylcobalamin. In the face of vitamin B deficiency, conversion of methylmalonyl-CoA to succinyl-CoA cannot take place, which results in accumulation of methylmalonyl-CoA and aberrant fatty acid synthesis. In the other enzymatic reaction, methylcobalamin supports the methionine synthase reaction, which is essential for normal metabolism of folate. The folate-cobalamin interaction is pivotal for normal synthesis of purines and pyrimidines and the transfer of the methyl group to cobalamin is essential for the adequate supply of tetrahydrofolate, the substrate"
"name of ""a-scorbic acid"" for the molecule, with L-ascorbic acid as its formal chemical name. During World War II, he was a member of the MAUD Committee which over saw research on the British atomic bomb project. Haworth is commemorated at the University of Birmingham in the Haworth Building, which houses most of the University of Birmingham School of Chemistry. The School has a Haworth Chair of Chemistry, from 2007 held by Professor Nigel Simpkins. In 1977 the Royal Mail issued a postage stamp (one of a series of four) featuring Haworth's achievement in synthesising vitamin C and his Nobel"
"and also regenerator of other antioxidants. Plants use multiple pathways to synthesize vitamin C. The major pathway starts with glucose, fructose or mannose (all simple sugars) and proceeds to L-galactose, L-galactonolactone and ascorbic acid. There is feedback regulation in place, in that the presence of ascorbic acid inhibits enzymes in the synthesis pathway. This process follows a diurnal rhythm, so that enzyme expression peaks in the morning to support biosynthesis later on when mid-day sunlight intensity demands high ascorbic acid concentrations. Minor pathways may be specific to certain parts of plants; these can be either identical to the vertebrate pathway"
"the National Academy of Sciences in 1978 on the basis of that work. Halver carried out research on Vitamin C in its many forms. His research showed that Vitamin C1 (Ascorbic Acid) the active form of C, is required by the body to create new cells and repair cells. His work also showed that C2 though C6 are other forms of C, some of which are stable, and that effectiveness of C1 breaks down when exposed to heat and light. His research showed that animal feeds that use the stable forms of C in their diet formulation can have a"
"time it was shown that not all vitamins are amines, the word was already ubiquitous. In 1920, Jack Cecil Drummond proposed that the final ""e"" be dropped to deemphasize the ""amine"" reference, after researchers began to suspect that not all ""vitamines"" (in particular, vitamin A) have an amine component. In 1930, Paul Karrer elucidated the correct structure for beta-carotene, the main precursor of vitamin A, and identified other carotenoids. Karrer and Norman Haworth confirmed Albert Szent-Györgyi's discovery of ascorbic acid and made significant contributions to the chemistry of flavins, which led to the identification of lactoflavin. For their investigations on"
"Based on that study, the American Burn Association (ABA) considers high-dose ascorbic acid an option to be considered for adjuvant therapy in addition to the more accepted standard treatments. Atrial fibrillation (AF) is a common cardiac rhythm disturbance and it is associated with oxidative stress. Four meta-analyses have concluded that there is strong evidence that 1-2 g/day of vitamin C before and after cardiac operations can decrease the risk of post-operative AF. However, five randomized studies did not find benefit in the USA, so that the benefit was restricted to less wealthy countries. Exercise-induced bronchoconstriction (EIB) indicates acute narrowing of"
"are necessary for iron absorption. In 1927, Adolf Otto Reinhold Windaus synthesized vitamin D, and was awarded the Nobel Prize in Chemistry in 1928. In 1928, Albert Szent-Györgyi isolated ascorbic acid, and in 1932 proved that it is vitamin C by preventing scurvy. In 1935, he synthesized it, and in 1937, he won a Nobel Prize for his efforts. Szent-Györgyi concurrently elucidated much of the citric acid cycle. In the 1930s, William Cumming Rose identified essential amino acids, necessary protein components that the body cannot synthesize. In 1935, Underwood and Marston independently discovered the necessity of cobalt. In 1936, Eugene"
"Antioxidant Antioxidants are compounds that inhibit oxidation. Oxidation is a chemical reaction that can produce free radicals, thereby leading to chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid (vitamin C) terminate these chain reactions. To balance the oxidative state, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione and enzymes (e.g., catalase and superoxide dismutase), produced internally, or the dietary antioxidants vitamin C, and vitamin E. The term ""antioxidant"" is mostly used for two entirely different groups of substances: industrial chemicals that are added to products to prevent oxidation,"
"Esmond Emerson Snell Esmond Emerson Snell (September 22, 1914 – December 9, 2003) was an American biochemist who spent his career researching vitamins and nutritional requirements of bacteria and yeast. He is well known for his study of lactic acid-producing bacteria, developing microbiological assays for a number of key nutrients; the discovery of more than half of known vitamins has been attributed to the use of this work. He discovered several B vitamins, including folic acid, and characterized the biochemistry of vitamin B6 (also known as pyrixodal). The fourth of five children, Snell was born in 1914 in Salt Lake"
"by various lipoxygenases, cyclooxygenases, certain cytochrome P450 enzymes (the CYP monooxygenases), and non-enzymatic autoxidation mechanisms to mono-hydroxyl products viz., 13-Hydroxyoctadecadienoic acid and 9-Hydroxyoctadecadienoic acid; these two hydroxy metabolites are enzymatically oxidized to their keto metabolites, 13-oxo-octadecadienoic acid and 9-oxo-octadecdienoic acid. Certain cytochrome P450 enzymes, the CYP epoxygenases, metabolize LA to epoxide products viz., its 12,13-epoxide, Vernolic acid and its 9,10-epoxide, Coronaric acid. All of these LA products have bioactivity and are implicated in human physiology and pathology as indicated in the cited linkages. Linoleic acid is an essential fatty acid that must be consumed for proper health. A diet deficient"
"oxytocin nonapeptide is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM). The activity of the PAM enzyme system is dependent upon vitamin C (ascorbate), which is a necessary vitamin cofactor. By chance, sodium ascorbate by itself was found to stimulate the production of oxytocin from ovarian tissue over a range of concentrations in a dose-dependent manner. Many of the same tissues (""e.g."" ovaries, testes, eyes, adrenals, placenta, thymus, pancreas) where PAM (and oxytocin by default) is found are also known to store higher concentrations of vitamin C. Oxytocin is known to be metabolized by the oxytocinase, leucyl/cystinyl aminopeptidase. Other oxytocinases are also"
"Alpha-Tocopherol α-Tocopherol is a type of vitamin E. It has E number ""E307"". Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. All feature a chromane ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain which allows for penetration into biological membranes. Compared to the others, α-tocopherol is preferentially absorbed and accumulated in humans. α-Tocopherol has three stereocenters, so it is a chiral molecule. The eight stereoisomers of α-tocopherol differ the configuration on these stereocenters. ""RRR""-α-tocopherol is the natural one. Older name of ""RRR""-α-tocopherol is ""d""-α-tocopherol,"