Definition of enzyme in US English:



  • A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

    Most enzymes are proteins with large complex molecules whose action depends on their particular molecular shape. Some enzymes control reactions within cells and some, such as the enzymes involved in digestion, outside them

    • ‘This is probably due to the presence of other enzymes besides the protease.’
    • ‘It appears to be due, in large part, to the activity of a specific enzyme, cytokinin oxidase.’
    • ‘Among these anaerobic proteins are enzymes involved in glycolysis and related processes.’
    • ‘They can act as real enzymes and, by analogy to protein enzymes, are called ribozymes.’
    • ‘It is clear that cells have a variety of relatively specific enzymes able to degrade these compounds.’


Late 19th century: coined in German from modern Greek enzumos ‘leavened’, from en- ‘within’ + Greek zumē ‘leaven’.