lactase

(noun)

a β-galactosidase enzyme that is involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers.

Related Terms

Examples of lactase in the following topics:

  • Lactose Intolerance

    • Lactose intolerance is the inability to digest lactose, a sugar found in milk, due to a lack of the enzyme lactase.
    • Most mammals normally become lactose intolerant after weaning, but some human populations have developed lactase persistence, in which lactase production continues into adulthood.
    • Primary lactase deficiency is genetic, only affects adults, and is caused by the absence of a lactase persistence allele.
    • Congenital lactase deficiency is a very rare, autosomal recessive genetic disorder that prevents lactase expression from birth.
    • Congenital lactase deficiency (CLD), where the production of lactase is inhibited from birth, can be dangerous in any society because of infants' nutritional reliance on breast milk during their first months.

  • Chemical Digestion of Carbohydrates, Proteins, Lipids, and Nucleic Acids

    • Lactase is an enzyme that breaks down the disaccharide lactose into its component parts, glucose and galactose, which can also be absorbed by the small intestine.
    • Approximately half the adult population produces only small amounts of lactase and are therefore unable to eat milk-based foods.

  • Absorption of Monosaccharides, Amino Acids, Dipeptides, Tripeptides, Lipids, Electrolytes, Vitamins, and Water

    • The lactase enzyme breaks down lactose, milk sugar.
    • However, lactase production ceases after weaning in most populations so that adults in those populations experience gastric discomfort or distress when eating dairy products.
    • Other brush border enzymes are maltase, sucrase, and lactase.
    • Lactase is absent in most adult humans and for them lactose, like most polysaccharides, are not digested in the small intestine.

  • Digestive Processes of the Small Intestine

    • Other brush border enzymes are maltase, sucrase, and lactase.
    • Lactase is absent in most adult humans and for them lactose, like most poly-saccharides, is not digested in the small intestine.

  • Galactosemia and Glycogen Storage Disease

    • Lactose in food (such as dairy products) is broken down by the enzyme lactase into glucose and galactose.
    • Lactose intolerant individuals have an acquired or inherited shortage of the enzyme lactase, and experience abdominal pains after ingesting dairy products, but no long-term effects.

  • Histology of the Large Intestine

    • These enzymes include peptidases, sucrase, maltase, lactase and intestinal lipase.

  • Hydrolysis

    • For instance, carbohydrates are broken down by amylase, sucrase, lactase, or maltase.

  • Digestion and Absorption

    • These disaccharides are then broken down into monosaccharides by enzymes called maltases, sucrases, and lactases.
    • Sucrose (table sugar) and lactose (milk sugar) are broken down by sucrase and lactase, respectively.

  • Malabsorption of Nutrients

    • Lactase deficiency, which prevents the breakdown of lactose, is a common cause of malabsorption.