Home » The class of enzymes that catalyzes synthetic reactions where two molecules are joined together and ATP is used is Enzymology MCQs The class of enzymes that catalyzes synthetic reactions where two molecules are joined together and ATP is used is January 22, 2022 26 Views Q. The class of enzymes that catalyzes synthetic reactions where two molecules are joined together and ATP is used is A. Hydrolases B. Lyases C. Ligases D. Isomerases Answer: Ligases