Definition of lactase in US English:

lactase

noun

Biochemistry
  • An enzyme that catalyzes 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 role of lactase is to hydrolyze lactose into galactose.’
    • ‘Many people take extra doses of naturally produced enzymes, such as lactase, pepsin and trypsin, in supplement form.’
    • ‘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.’

Origin

Late 19th century: from lactose + -ase.

Pronunciation

lactase

/ˈlækteɪs//ˈlaktās/