-ase

An enzyme.

The final part of diastase, derived from Greek diastasis, separation.

Enzymes are substances produced by living organisms which catalyse biochemical reactions. The first named, in the 1830s, was diastase, which appears during the malting of barley and converts starch into sugar (it is now better known as amylase, from Latin amylum, starch); other examples named on its model were zymase (Greek zumē, leaven) and maltase; together these convert the sugar maltose into alcohol. A very large number of other enzymes has been discovered in the period since, of which a few are given in the list below.

Examples of words in -ase
Names are from English nouns unless otherwise stated.

carboxylase

catalyses the addition of a carboxyl group to a specified substrate, the reverse process being carried out by decarboxylase

carboxyl

cholinesterase

one of a group — especially acetylcholinesterase) — which hydrolyses esters of choline

choline

hydrolase

catalyses the hydrolysis of a particular substrate

hydrolysis

isomerase

converts a compound to an isomer

isomer

lipase

catalyses the breakdown of fats to fatty acids and glycerol or other alcohols

Greek lipos, fat

polymerase

brings about the formation of a particular polymer, especially DNA or RNA

polymer

protease

breaks down proteins and peptides

protein

proteinase or endopeptidase

breaks peptide bonds other than terminal ones in a peptide chain

protein

reductase

promotes the chemical reduction of a specified substance

reduce

synthase

catalyses the linking together of two molecules, especially without the direct involvement of ATP

synthesis

transcriptase

catalyses the formation of RNA from a DNA template during transcription with reverse transcriptase doing the opposite

transcription