Definition of lactase in English:



mass nounBiochemistry
  • An enzyme which catalyses the hydrolysis of lactose to glucose and galactose.

    • ‘While most people can digest lactose with no difficulty, some have trouble because they do not produce the enzyme lactase, which splits lactose into digestible parts.’
    • ‘The enzyme lactase breaks down the lactose to galactose and glucose.’
    • ‘Lactose, the sugar present in milk, is split in the small intestine by the enzyme lactase into its constituent glucose and galactose molecules, allowing absorption of the glucose.’
    • ‘Many people take extra doses of naturally produced enzymes, such as lactase, pepsin and trypsin, in supplement form.’
    • ‘The role of lactase is to hydrolyze lactose into galactose.’


Late 19th century: from lactose + -ase.