Which substance can act as a coenzyme?

Coenzymes are organic molecules that assist enzymes in catalyzing reactions. They usually serve as carriers for chemical groups or electrons and are essential for the proper functioning of enzymes. Among the options provided, ATP (adenosine triphosphate) is capable of acting as a coenzyme because it not only serves as an energy source for cellular processes but also plays a crucial role in various biochemical reactions by transferring phosphate groups.

These phosphate groups are vital for the activation of some enzymes, thereby enhancing their catalytic activity. This makes ATP integral to various metabolic pathways, including phosphorylation reactions, which are important for energy transfer, making it a classic example of a coenzyme in biochemical reactions.

In contrast, water and sodium chloride do not serve this function; water is primarily a solvent and participates in hydrolysis but does not act as a coenzyme. Sodium chloride functions as an ionic compound that helps maintain osmotic balance and is not involved in enzymatic functions. Glucose is a substrate energy source but lacks the role of a coenzyme in catalyzing enzymatic reactions.