Enzymes have been categorized into six different categories by the type of reaction in which they catalyze. Ligase enzymes are enzymes that catalyze reactions which make bonds to join together (ligate) smaller molecules to make larger ones. Ligase enzymes tend to raise the energy of a system, but the hydrolysis of ATP is often coupled with these reaction to make the reaction spontaneous. All enzymes tend to have the same basic catalytic effect in that they lower the overall activation energy often by moving the two substituents into close proximity.
The active site of these enzymes is the area of the enzyme that binds the substrates. The interactions that hold the substrates in the active site are often many weak non-covalent interactions between amino acids and ligands. These interactions are electrostatic interactions, hydrogen bonds, van der Waals forces, and hydrophobic interactions. To better understand the function and structure of ligase enzymes a more detailed look of three examples will be taken look at below. These three ligase enzymes are as followed: Threonyl-tRNA synthetase, Acetyl-CoA carboxylase, and Succinyl-CoA synthetase.
[Home] [Introduction to Ligases] [threonyl-tRNA synthetase] [acetyl-CoA Carboxylase]