Which mineral acts as a cofactor for more than 300 enzymes?

• A. Calcium
• B. Magnesium
• C. Potassium
• D. Sodium

Answer: (B)

Magnesium acts as a critical cofactor for a very large set of enzymes because it forms complexes with ATP, creating Mg-ATP, which is the actual substrate for most ATP-dependent enzymes. This pairing stabilizes the negative charges on phosphate groups and properly orients substrates for catalysis, enabling reactions across many pathways such as glycolysis, energy production, and nucleic acid synthesis. Magnesium also helps stabilize ribosomes and is involved in activation of many enzymes in various processes. Among the minerals listed, magnesium uniquely serves as a broad, universal cofactor for hundreds of enzymes, a role not shared to the same extent by calcium, potassium, or sodium, which are more central to signaling, electrolyte balance, and membrane potential rather than serving as widespread enzyme cofactors.