Explain how enzymes catalyst chemical reactions.

A fundamental task of proteins is to act as enzymes—catalysts that increase the rate of virtually all the chemical reactions within cells. Although RNAs are capable of catalyzing some reactions, most biological reactions are catalyzed by proteins.

Explanation:

In a chemical reaction, enzyme acts as catalyst. It accelerates the rate of reaction by lowering the activation energy needed to start a reaction. The enzyme converts substrate into product without changing itself.  Thus enzymes speed up reactions by lowering activation energy.