LIGASES
Ligases (synthetases) are a family of ferments, which catalyze addition reactions of two different molecules to each other at the expense of the energy of coupled reaction of hydrolysis of nucleoside triphosphate (mostly, ATP). Ligases are divided into classes according to the character of the bond formed (C-O, C-S, C-N or C-C). Biotin acts as a coenzyme. Ligases participate in biosynthesis of proteins, lipids and carbohydrates. Over 100 ligases are known.