This enzyme is an aminotransferase that transfers amine groups from on compound to another. The Aspartate Aminotransferase catalyzes a reversible transamination reaction. The reaction is:

Aspartate + 2-Oxoglutarate -> Oxaloacetate + Glutamate (Jeffrey)

This is done by a transamination reaction that interconverts carbonyl and amino groups.

+

->

+

Aspartate aminotransferase aids in amino acid an carbohydrate metabolism. It also transfers the reducing equivalents into the mitochondria and chlororplasts through the malate/aspartate shuttle (Jeffrey).

Aspartate Aminotransferase alternates between two forms. The first is the PLP (Pyridoxyl Phosphate) form. In this form it behaves as a cofactor and is bound to the active site by a Schiff base linkage. The second form is a PMP (Pyridoxamin phosphate) form (Jeffrey).

Thermodynamics:

When the temperature ranges from 25 to 37 degrees Celsius there are several significant changes in the Michaelis constant (Rej).

A temperature increase of five degrees increases the K max value two-fold. The catalytic efficiency increases as the carbon number of the substrate increases (Kawaguchi).

Structure:

There are 2 proline in the cis confomaiton in all AspATs. The structure is made of both Alpha helices and Beta sheets. The seventh Beta sheet strand is antiparallel to the rest. This protein also has two subunits that can be further separated into 2 subunits. The first domain (N-terminus)is a large cofactor binding domain. The second domain is much smaller than the first (Vacca).

Aspartate Aminotransferase contains key residues that are determined by steric constraints and polar interactions.

ARG 386 bind the carboxylate group in the small domain and ARG 292 interacts with a carbonyl group in the large domain.

There are also 2 active sites. These sites consist of residues of both subunits in the large domain and one subunit of the small domain (Birolo).