Affixes: -ase

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-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

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