Lactase

Lactase
Enzyme that breaks down the milk sugar lactose into glucose and galactose. Persons with a deficiency of lactase in the gut can develop abdominal cramping and diarrhea after ingesting milk products.
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SYN: β-d-galactosidase.

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lac·tase 'lak-.tās, -.tāz n an enzyme that hydrolyzes esp. lactose to glucose and galactose and occurs esp. in the intestines of young mammals and in yeasts

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n.
an enzyme, secreted by the glands of the small intestine, that converts lactose (milk sugar) into glucose and galactose during digestion.

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lac·tase (lakґtās) a β-galactosidase [EC 3.2.1.23] occurring in the brush border membrane of the intestinal mucosa; together with glycosylceramidase (phlorizin hydrolase), it forms the β-glycosidase complex (q.v.). The enzyme catalyzes the hydrolytic cleavage of lactose to galactose and glucose and also cleaves terminal nonreducing galactose residues from β-glycosides with large hydrophilic aglycons. Reduced or absent enzyme activity (lactase deficiency) may result in symptoms of lactose intolerance. [USP] an official preparation of lactase, derived from the mold Aspergillus oryzae.

Medical dictionary. 2011.

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