enzyme
noun [ C ] uk/ˈen.zaɪm/ us/ˈen.zaɪm/
酶
any of a group of chemical substances that are produced by living cells and cause particular chemical reactions to happen while not being changed themselves
An enzyme in the saliva of the mouth starts the process of breaking down the food. 由于唾液中酶的作用，食物进入口腔时就开始了分解过程。