lactase

lactase

 [lak´tās]

β-d-galactosidase; an enzyme in the intestinal mucosa that hydrolyzes lactose, producing glucose and galactose.

lactase deficiency a deficiency of intestinal lactase, which causes abdominal distention and cramping and often diarrhea when milk is drunk. The condition is usually hereditary with an onset between infancy and early adulthood, and is more common in Blacks, American Indians, and East Asians (70 to 90 per cent) than in Whites (10 to 15 per cent). It may also occur secondary to massive small bowel resection or to diseases involving the mucosa, such as celiac disease, Crohn's disease, tropical sprue, and ulcerative colitis.

β-d-ga·lac·to·sid·ase

(gă-lak'tō-sīd'ās),

An enzyme that catalyzes the hydrolysis of lactose into d-glucose and d-galactose, as well as the hydrolysis of other β-d-galactosides; it also catalyzes galactotransferase reactions; a deficiency of β-d-galactosidase leads to problems in the intestinal digestion of lactose; used in the production of milk products for adults who lack the intestinal enzyme; a defect of one isozyme of β-d-galactosidase is associated with Morquio syndrome type B. Compare: lactase persistence, lactase restriction.

Synonym(s): lactase

lactase

(lăk′tās′)

n.

An enzyme occurring in certain yeasts and in the intestinal juices of mammals and catalyzing the hydrolysis of lactose into glucose and galactose.

GLB1

A gene on chromosome 3p21.33 that encodes beta-galactosidase-1, a lysosomal enzyme that hydrolyses the terminal beta-galactose from gangliosides and other glycoconjugates.

Molecular biology
GLB1 mutations cause GM1-gangliosidosis and mucopolysaccharidosis IV (Morquio B syndrome).

β

Abbreviation for beta.

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be·ta

(β) (bā'tă)

1. Second letter of the Greek alphabet.

2. chemistry Denotes the second in a series, the second carbon from a functional (e.g., carboxylic) group, or the direction of a chemical bond toward the viewer. For terms with the prefix β, see the specific term.

lactase

An enzyme that brings about the HYDROLYSIS of LACTOSE to glucose (dextrose) and galactose. Beta-galactosidase.

lactase

an enzyme that splits the disaccharide LACTOSE into galactose and glucose, secreted as part of the intestinal juice by glands in the SMALL INTESTINE wall. Lactase is also produced in ENZYME INDUCTION by bacteria (see OPERON MODEL).