What component assists in enzyme activity that is not a protein?

Cofactors are non-protein molecules that play a critical role in the function of enzymes. They enhance the ability of enzymes to catalyze biochemical reactions by stabilizing enzyme-substrate complexes, assisting in the orientation of substrates, or facilitating the conversion of substrates into products. Cofactors can be metal ions, such as zinc or magnesium, or organic molecules, known as coenzymes, such as NAD+ or coenzyme A.

The other components listed play different roles in the enzymatic process. The substrate is the molecule upon which the enzyme acts. Inhibitors are molecules that decrease enzyme activity by binding to the enzyme and preventing it from catalyzing reactions. The product is the end result of the enzymatic reaction rather than a contributor to enzyme activity. Therefore, the presence of cofactors is essential for many enzymes to achieve their full catalytic potential, making them a key component that assists in enzyme activity but is not a protein itself.