A disaccharide present in mammalian milk, occurring naturally as α- and β-l.; obtained from cow's milk and used in modified milk preparation, in food for infants and convalescents, and in pharmaceutical preparations; large doses act as an osmotic diuretic and as a laxative. Human milk contains 6.7% l.. SYN: milk sugar, saccharum lactis.
- l. synthase the enzyme responsible for the synthesis of l., catalyzing the reaction between UDP-galactose and d-glucose to l. and UDP.

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lac·tose 'lak-.tōs, -.tōz n a disaccharide sugar C12H22O11 that is present in milk, yields glucose and galactose upon hydrolysis, yields esp. lactic acid upon fermentation, and is used chiefly in foods, medicines, and culture media (as for the manufacture of penicillin) called also milk sugar

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a sugar, consisting of one molecule of glucose and one of galactose, found only in milk. Lactose is split into its constituent sugars by the enzyme lactase, which is secreted in the small intestine. This enzyme is missing or is of low activity in certain people of some Eastern and African races. This leads to the inability to absorb lactose, known as lactose intolerance.

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lac·tose (lakґtōs) [L. lac, gen. lactis milk] a reducing disaccharide occurring as the D-isomer, in both α- and β-configurations, as a major constituent of mammalian milk; on hydrolysis by acids or intestinal lactase, it forms one residue each of galactose and glucose. Cf. lactose intolerance, under intolerance. Lactose is used as a tablet and capsule diluent, a powder bulking agent, in infant feeding formulas, and as a nutritional supplement.

Medical dictionary. 2011.

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Look at other dictionaries:

  • Lactose — (Milk sugar) IUPAC name β D galactopyranosyl (1→4) D glucose …   Wikipedia

  • Lactose — Général Nom IUPAC β D galactopyrannosyl (1→4)β D glucopyrannose Synonymes …   Wikipédia en Français

  • lactose — [ laktoz ] n. m. • 1843, aussi fém.; de lact(o) et 1. ose ♦ Chim. Diholoside contenu dans le lait des mammifères (C12H22O11), hydrolysable en glucose et galactose. ● lactose nom masculin Sucre (molécule à 12 atomes de carbone) contenu dans le… …   Encyclopédie Universelle

  • lactose — lac tose (l[a^]k t[=o]s ), n. 1. (Physiol. Chem.) The main sugar present in milk, called also {sugar of milk} or {milk sugar}. When isolated pure it is obtained crystalline; it is separable from the whey by evaporation and crystallization. It is… …   The Collaborative International Dictionary of English

  • lactose — lactose. См. молочный сахар. (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.

  • Lactose — Lactose, der durch Säuren veränderte Milchzucker, s.d …   Pierer's Universal-Lexikon

  • Lactose — Lactose, Milchzucker, Kohlenhydrat aus der Gruppe der ⇒ Oligosaccharide; Disaccharid aus den β 1,4 glykosidisch verknüpften Monosacchariden Glucose und Galactose. L. ist in der Milch der Säuger vorhanden und wird von den Milchsäurebakterien in… …   Deutsch wörterbuch der biologie

  • Lactose — vgl. Laktose …   Das Wörterbuch medizinischer Fachausdrücke

  • lactose — sugar from milk, 1858, from French, coined by French chemist Marcelin Pierre Eugène Berthelot (1827 1907) from L. lac (gen. lactis) milk (see LACTATION (Cf. lactation)) + chemical suffix ose …   Etymology dictionary

  • lactose — |lâct| s. f. Açúcar de leite …   Dicionário da Língua Portuguesa

  • lactose — ► NOUN Chemistry ▪ a compound sugar present in milk …   English terms dictionary

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