Ligase

In biochemistry, a ligase is an enzyme that can catalyze the joining (ligation) of two molecules by forming a new chemical bond. This is typically via hydrolysis of a small pendant chemical group on one of the molecules, typically resulting in the formation of new C-O, C-S, or C-N bonds. For example, DNA ligase can join two complementary fragments of nucleic acid by forming phosphodiester bonds, and repair single-stranded breaks that arise in double stranded DNA during replication.

In general, a ligase catalyzes the following dehydration reaction, thus joining molecules A and B:

A-OH + B-H → A–B + H₂O