What term refers to a substance that works with an enzyme to enhance its function?

The term that refers to a substance that works with an enzyme to enhance its function is coenzyme. Coenzymes are typically organic molecules that bind to enzymes and assist in the catalytic process, often helping to facilitate the transfer of electrons, atoms, or functional groups as part of the enzymatic reaction. They can be vitamins or derived from vitamins, contributing to the overall activity of the enzyme by making it more efficient or allowing it to catalyze reactions it otherwise could not.

In contrast, a catalyst is a broader term that refers to any substance that increases the rate of a chemical reaction without being consumed in the process but does not specifically denote a partnership with enzymes. While an activator may enhance the activity of an enzyme, it is usually categorized differently from coenzymes, which typically involve a more integral role in the biochemical reaction. An inhibitor, on the other hand, would decrease or block an enzyme's activity, contrasting with the enhancing role of a coenzyme.