Enzymes catalysing the synthetic reactions where two molecules are joined together and ATP is used; belongs to which class?
Oxidoreductases: Enzymes involved in oxidation-reduction reactions.
Transferases: Enzymes that catalyse the transfer of functional groups.
Hydrolases: Enzymes that bring about hydrolysis of various compounds.
Lyases: Enzymes specialized in the addition or removal of water, ammonia, CO2 etc.
Isomerases: Enzymes involved in all the isomerization reactions.
Ligases: Enzymes catalysing the synthetic reactions (Greek: ligate-to bind) where two molecules are joined together and ATP is used.

Reference - satyanarayana Pg-87
Hydrolase
Lyase
Ligase
Transferase