Ligase

In biochemistry, a ligase (from the Latin verb ligāre — "to bind" or "to glue together") is an enzyme that can catalyse the joining of two large molecules by forming a new chemical bond, usually with accompanying hydrolysis of a small chemical group pendant to one of the larger molecules.
The common names of ligase enzymes often include the word "ligase", such as DNA ligase, an enzyme commonly used in molecular biology laboratories to join together DNA fragments. Other common names for ligases include synthetase, because they are used to synthesize new molecules, or carboxylase when they are used to add carbon dioxide to a molecule.
Note that "synthetase" should not be confused with synthases, as synthases do not use energy from nucleoside triphosphates (such as ATP, GTP, CTP, TTP and UTP) and belong to the lyase group, while ligases do use nucleoside triphosphates.