General term for a number of unrelated organic substances that occur in many foods in small amounts and that are necessary in trace amounts for the normal metabolic functioning of the body. They may be water-soluble or fat-soluble.
Molecules such as acetyl CoA, biotin, and ATP are known as coenzymes because they are bound tightly to various enzyme surfaces and are essential for the activity of the enzyme. Many of the small molecules known as vitamins, which are required in trace amounts in the diet, are converted to coenzymes in the body.
