Which type of enzyme catalyzes oxidation-reduction reactions?

• A. Hydrolase
• B. Ligase
• C. Oxidoreductase
• D. Transferase

Answer: (C)

Oxidoreductases are the class of enzymes that specifically facilitate oxidation-reduction reactions. In biological systems, these reactions involve the transfer of electrons from one molecule to another, which can cause the oxidation of one substance while reducing another. This is a critical process in various metabolic pathways, including cellular respiration and photosynthesis.

Oxidoreductases typically possess coenzymes such as NAD+ or FAD, which help in the acceptance and donation of electrons during the reaction. These enzymes play a vital role in maintaining the balance of redox states within cells, being integral to energy production and various biosynthetic pathways.

The other types of enzymes, while essential in their own right, perform different functions. Hydrolases catalyze hydrolysis reactions, breaking down compounds by adding water. Ligases are involved in joining two molecules together, usually forming a new bond with the input of energy, often derived from ATP. Transferases transfer functional groups from one molecule to another without involving oxidation or reduction. Thus, oxidoreductases are uniquely important for catalyzing reactions that deal with the transfer of electrons, making them essential for the redox reactions critical to cellular metabolism and energy transfer.