ligase

Ligase 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 dependent to one of the larger molecules or the enzyme catalyising the linking together of two compounds.

In general, a ligase catalyzes the following reaction: Ab + C → A–C + b or sometimes Ab + cD → A–D + b + c. (Where the lowercase letters signify the small, dependent groups.)

Ligases include for example also aminoacyl-tRNA synthethase, catalyzing amino acids connected to the tRNA.