Traditional term for 1,2-diacyl-sn-glycero-3-phosphocholines or 3-sn-phosphatidylcholines, phospholipids that on hydrolysis yield two fatty acid molecules and a molecule each of glycerophosphoric acid and choline. In some varieties of l., both fatty acid s are saturated, others contain only unsaturated acids ( e.g., oleic, linoleic, or arachidonic acid); in others again, one fatty acid is saturated, the other unsaturated. Lecithins are yellowish or brown waxy substances, readily miscible in water, in which they appear under the microscope as irregular elongated particles known as “myelin forms,” and are found in nervous tissue, especially in the myelin sheaths, in egg yolk, and as essential constituents of animal and vegetable cells. [G. lekithos, egg yolk]
- l. acyltransferase SYN: l.-cholesterol acyltransferase.
- l.-cholesterol transferase a plasma enzyme that catalyzes the uptake of cholesterol esters by intermediate-density lipoproteins formed by high density lipoproteins.

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lec·i·thin 'les-ə-thən n any of several waxy hygroscopic phospholipids in which phosphatidic acid has formed an ester with choline and which are widely distributed in animals and plants, form colloidal solutions in water, and have emulsifying, wetting, and antioxidant properties also a mixture of or a substance rich in lecithins called also phosphatidylcholine

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one of a group of phospholipid that are important constituents of cell membranes and are involved in the metabolism of fat by the liver. An example is phosphatidylcholine. Lecithins are present in the surfactant that occurs in fetal lung tissue. The lecithin-sphingomyelin ratio (LS ratio) is used as a measure of fetal lung maturity; an LS ratio below 2 indicates a higher risk of respiratory distress syndrome (RDS). In such cases cortisone may be given to stimulate fetal lung maturity and hence reduce the risk of RDS in the newborn.

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lec·i·thin (lesґĭ-thin) phosphatidylcholine.

Medical dictionary. 2011.

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  • Lecithin — is any of a group of yellow brownish fatty substances occurring in animal and plant tissues, and in egg yolk, composed of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides, and phospholipids (e.g., phosphatidylcholine,… …   Wikipedia

  • Lecithin — Lec i*thin, n. [Gr. le kiqos the yolk of an egg.] (Physiol. Chem.) A complex, nitrogenous phosphorized substance widely distributed through the animal body, and especially conspicuous in the brain and nerve tissue, in yolk of eggs, and in the… …   The Collaborative International Dictionary of English

  • Lecithīn — Lecithīn, ist nach Gobley der phosphorhaltige Körper der Höhner u. Karpfeneier, eine neutrale Substanz, welche beim Behandeln mit Mineralsäuren u. Alkalien Öl , Margarin u. Glycerinphosphorsäure liefert …   Pierer's Universal-Lexikon

  • Lecithīn — Lecithīn, ein phosphorhaltiger Körper, der in Tier und Pflanzenzellen weitverbreitet vorkommt und besonders im Gehirn, in Nerven, Samen, im Blut, namentlich bei hochgradiger Leukämie, im Eiter, in der Galle, Milch, im Eidotter, Kaviar, in Hefe,… …   Meyers Großes Konversations-Lexikon

  • Lecithin — Lecithīn, fettähnliche Substanz, charakteristischer Bestandteil des Gehirns, der Nerven und des Eidotters, überhaupt im Tier und Pflanzenkörper verbreitet, knetbare, nicht deutlich kristallinische Masse, quillt mit Wasser; zerfällt durch Säuren… …   Kleines Konversations-Lexikon

  • Lecithin — ⇒ Phospholipide …   Deutsch wörterbuch der biologie

  • lecithin — fatty substance found in the yolks of eggs (among other places), 1861, from Fr. lécithine (coined 1850 by N.T. Gobley), from Gk. lekithos egg yolk, + chemical suffix INE (Cf. ine) (2). Gk. lekithos is of unknown origin …   Etymology dictionary

  • lecithin — [les′i thin] n. [< Gr lekithos, yolk of an egg + IN1] any of several phosphatides found in nerve tissue, blood, milk, egg yolk, soybeans, corn, etc.: used in medicine, foods, cosmetics, etc. as a wetting, emulsifying, and penetrating agent …   English World dictionary

  • Lecithin — Lecithine (deutsch: Lezithine, altgriechisch: λέκιθος = Eidotter) ist der klassische Name für eine Gruppe chemischer Verbindungen, die so genannten Phosphatidylcholine. Dabei handelt es sich um Lipide, genauer Phospholipide, die sich aus… …   Deutsch Wikipedia

  • lecithin — /les euh thin/, n. 1. Biochem. any of a group of phospholipids, occurring in animal and plant tissues and egg yolk, composed of units of choline, phosphoric acid, fatty acids, and glycerol. 2. a commercial form of this substance, obtained chiefly …   Universalium

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