Biotin


Biotin
A water-soluble B-complex vitamin involved in carbon dioxide transfer and therefore essential to the metabolism of carbohydrate and fat. A balanced diet usually contains enough biotin. Foods with high biotin levels include nuts, cereals, green leafy vegetables and milk. Biotin deficiency, which is characterized by hair loss and a scaly red rash, can occur with prolonged intravenous feeding or the frequent consumption of raw egg whites which contain a biotin antagonist called avidin. Biotin supplementation is recommended during pregnancy because the biotin requirement rises during pregnancy and a substantial number of pregnant women become biotin depleted. Extra biotin is also needed during long-term anticonvulsant treatment which depletes biotin.
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The d-isomer component of the vitamin B2 complex occurring in or required by most organisms and inactivated by avidin; participates in biologic carboxylations. It is a small molecule with a high affinity for avidin that can be readily coupled to a previously labeled antibody in order to allow visualization by enzymatic or histochemical means. SEE ALSO: avidin. SYN: coenzyme R, vitamin H, W factor.
- b. carboxylase a subunit of a number of enzymes ( E.G., acetyl-CoA carboxylase). It catalyzes the formation of carboxybiotin (on a b. carrier protein), ADP, and Pi from ATP, CO2 and b..
- b. oxidase an enzyme (probably nonspecific) catalyzing the beta-oxidation of the b. side chain.

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bi·o·tin 'bī-ət-ən n a colorless crystalline growth vitamin C10H16N2O3S of the vitamin B complex found esp. in yeast, liver, and egg yolk called also vitamin H

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n.
a vitamin of the B complex that is essential for the metabolism of fat, being involved in fatty acid synthesis and gluconeogenesis. A biotin deficiency is extremely rare in humans; it can be induced by eating large quantities of raw egg white, which contains a protein - avidin - that combines with biotin, making it unavailable to the body. Rich sources of the vitamin are egg yolk and liver.

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bio·tin (biґo-tin) 1.a water-soluble dicyclic monocarboxylic acid considered to be part of the vitamin B complex; it is an essential cofactor for several carboxylases, plays a role in the metabolism of fatty acids and the deamination of certain amino acids, and is also used in vitro in biochemical assays based on biotinylation (q.v.) of various molecules. Deficiencies in humans have occurred only after prolonged total parenteral nutrition not supplemented with biotin or on ingestion of large quantities of raw egg whites (see avidin); manifestations have included dermatologic, neurologic, and ocular disorders. In some animals, deficiency has resulted in graying and loss of hair. [USP] 2.a preparation of biotin, used as a nutritional supplement.

Medical dictionary. 2011.

Look at other dictionaries:

  • Biotin — Biotin[1] …   Wikipedia

  • biotin — i o*tin n. a B vitamin ({C10H16N2O3S}) that aids in body growth; called also {vitamin H} and {coenzyme R}. It functions as a coenzyme in many carboxylation reactions. Note: Biotin binds tightly to the substance avidin, found in raw egg whites.… …   The Collaborative International Dictionary of English

  • biotin — vitamin of the B group (also sometimes called vitamin H) essential for the growth of yeast, 1936, from Ger. Biotin (1936), from Gk. biotos life (see BIO (Cf. bio )) + chemical suffix IN (Cf. in) (2) …   Etymology dictionary

  • biotin — biòtīn m <G biotína> DEFINICIJA C10H16N2O3S, vitamin B grupe, prisutan u kvascu, žumanjku jajeta, jetri, prima se putem hrane, a sintetizira ga i normalna crijevna flora, u čovječjem organizmu deponira se u jetri ETIMOLOGIJA njem. Biotin ≃… …   Hrvatski jezični portal

  • biotin — biotin. См. витамин Н. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Biotin — Biotin, Vitamin H, zu den wasserlöslichen Vitaminen gehörende Verbindung aus zwei Fünfringen und der n Valeriansäure; als Coenzym insbesondere an CO2 Übertragungen beteiligt; reichlich enthalten in Leber, Niere, Eigelb, Hefe. Die Darmbakterien… …   Deutsch wörterbuch der biologie

  • biotin — ► NOUN ▪ a vitamin of the B complex, found in egg yolk, liver, and yeast, involved in the synthesis of fatty acids and glucose. ORIGIN from Greek bios life …   English terms dictionary

  • biotin — [bī′ə tin] n. [ BIOT(IC) + IN1] a bacterial growth factor, C10H16O3N2S, present in all living things; vitamin H: it is one of the vitamin B group and is found in liver, egg yolk, yeast, etc …   English World dictionary

  • Biotin — Strukturformel Allgemeines Trivialname Vitamin B7 Vitamin B8 Vitamin H …   Deutsch Wikipedia

  • biotin — /buy euh tin/, n. Biochem. a crystalline, water soluble vitamin, C10H16O3N2S, of the vitamin B complex, that is present in all living cells and functions as a growth factor and as a catalyst in carboxylation reactions. Also called vitamin H.… …   Universalium


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