Final answer:
Cofactors and coenzymes are essential non-protein molecules that enzymes need for activation and optimal function. They bind to enzymes, influence their structure, and assist in the chemical transactions of a substrate to a product. Examples include cofactors like metal ions and coenzymes derived from dietary vitamins.
Step-by-step explanation:
Sometimes even when catalysts are available, a cofactor is also required for a reaction to proceed. This is particularly true for enzymatic reactions that require additional non-protein helper molecules for optimal function.
Enzymes may require cofactors, which are inorganic ions like iron (Fe++) and magnesium (Mg++), to stabilize the enzyme's structure and function. An example is DNA polymerase, which needs zinc (Zn++) to build DNA molecules. Additionally, many enzymes rely on coenzymes, which are organic helper molecules often derived from dietary vitamins, such as vitamin C, which is crucial for enzymes that synthesize collagen in connective tissues. A notable enzyme complex, pyruvate dehydrogenase, demands both a cofactor (magnesium ion) and multiple organic coenzymes to catalyze the transformation of pyruvate, which is a crucial step in glucose metabolism.
Overall, the presence of specific cofactors and coenzymes is essential to activate apoenzymes (inactive forms), turning them into active holoenzymes and enabling a plethora of vital biochemical processes.