1) Accelerator 2) Catalyst 
A substance, such as an enzyme, that initiates or modifies the rate of a biological process and is generally consumed in that process, in contrast with a chemical catalyst, which accelerates a chemical reaction without being consumed.
A substance which catalyses biochemical processes in living things. The most well-known example is the enzyme. ... (09 Oct 1997) ... 
Type: Term Pronunciation: bī′ō-kat′ă-list Definitions: 1. A substance of biologic origin that can catalyze a reaction, an enzyme.
[n] - a biochemical catalyst such as an enzyme
biocatalyst A substance of biological origin that can catalyze a reaction; q.v. (quod vide = 'which see'), an enzyme.
noun a biochemical catalyst such as an enzyme