Question

What is the molecule on which an enzyme acts called?

Answer 1

It is called a substrate.

Explanation:

Enzymes catalyze the reactions of substrate molecules. If a molecule merely binds (and does not react), this molecule is called a "Ligand".

Of example, Glucose is a substrate for the hexokinase in the first step of glycolysis.

Gamma Amino Butyric Acid (GABA) is a neurotransmitter and ligand for GABA receptor proteins (ionotropic and G-protein coupled receptors or metabotropic receptors). GABA is not chemically modified - only binds.