Final answer:
Apoenzyme is not a cofactor; it is the protein part of an enzyme that needs a non-protein component like a cofactor or coenzyme to be active. Cofactors include metal ions and small organic molecules, whereas coenzymes are organic molecules that are essential for the activity of enzymes. The correct answer is option: B. Apoenzyme
Step-by-step explanation:
Among the options provided, the one that is not a cofactor is B. Apoenzyme. An apoenzyme is the protein part of an enzyme that requires a non-protein component to become active. The non-protein component can be either a cofactor (which are usually inorganic ions or small organic molecules) or a coenzyme (which is a specific type of organic cofactor, often derived from vitamins).
Cofactors are substances that many enzymes require to function optimally. They can include metal ions like iron (Fe++) and magnesium (Mg++), and their role is to stabilize enzyme conformation and function.
A coenzyme is an organic molecule that acts as a cofactor, and it is essential for the enzyme's activity. Prosthetic groups are another type of cofactor, which are tightly bound to a protein, helping it to function. Metal ions such as zinc, magnesium, and potassium also function as cofactors in various enzymatic processes.