Final answer:
An apoenzyme is the protein part of an enzyme that becomes active upon binding with a cofactor or coenzyme, with cofactors being inorganic metal ions and coenzymes typically being organic molecules derived from vitamins.
Step-by-step explanation:
An apoenzyme is the protein component of an enzyme, which requires the binding of a non-protein molecule called a cofactor or coenzyme to become an active enzyme, or holoenzyme. Cofactors are often inorganic metal ions such as Zn²⁺ or Mg²⁺, whereas coenzymes are organic molecules that are typically derived from vitamins. When a cofactor or coenzyme binds to an apoenzyme at its active site, the enzyme attains its proper structure and becomes capable of catalyzing its specific chemical reaction. An example of a cofactor is the zinc ion needed for the function of DNA polymerase, and examples of coenzymes include NADH and ATP, which provide high-energy electrons or phosphate groups to activate enzymes.