* * *
SYN: β-d-galactosidase.
* * *
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
* * *
n.
an enzyme, secreted by the glands of the small intestine, that converts lactose (milk sugar) into glucose and galactose during digestion.
* * *
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.