Answer the following question given this paragraph: 

Some enzymes require the presence of a non-protein molecule called a cofactor in order to function properly. Cofactors can be inorganic metal ions or small organic molecules. Many vitamins, such as B vitamins, act as cofactors. Some metal ions which function as cofactors for various enzymes include zinc, magnesium, potassium, and iron.


Q: Some enzymes require the presence of a non-protein molecule to function properly. what is that molecule called?


A:
cofactor