noun, plural: ligases
(biochemistry) An enzyme that catalyzes the binding of two molecules
An enzyme is a catalyst or a chemical produced by cells to speed up a biochemical reaction. It is usually a protein molecule with a characteristic sequence of amino acids that fold to produce a specific three-dimensional structure, which gives the molecule unique properties. Other molecule with catalytic activity is ribozyme, an enzyme made of RNA rather than protein. Enzymes may be classified and named according to the reaction they catalyze: (1) oxidoreductases, (2) transferases, (3) lyases, (4) isomerases, and (6) ligases.
Ligases are a group of enzymes that catalyze the binding of two molecules. An example is a DNA lygase that link two fragments of DNA by forming a phosphodiester bond.
Ligases are classified into six subclasses: (1) EC 6.1 (ligases forming carbon-oxygen bonds), (2) EC 6.2 (ligases forming carbon-sulfur bonds), (3) EC 6.3 (ligases forming carbon-nitrogen bonds), (4) EC 6.4 (ligases forming carbon-carbon bonds), (5) EC 6.5 (ligases forming phosphoric ester bonds), and (6) EC 6.6 (ligases forming mitrogen-metal bonds).