Partial purification and some properties of aspartate aminotransferase from the mantle tissue of Mytilus galloprovincialis Lam.

Aspartate aminotransferase (E.C.2.6.1.1; AST), is a pyridoxal phosphate dependent enzyme that occurs in virtually all organisms and plays a key role in intermediary nitrogen metabolism. Although AST was purified from a variety of plant and animal sources, it has not been purified previously from mantle tissue of Mytilus galloprovincialis Lam. In the present study we have partially purified AST from the mantle tissue of M. galloprovincialis and investigated some kinetic properties of the enzyme. The partially purified enzyme showed three protein and a single activity band in polyacrylamide gel electrophoresis. It was found that the enzyme exhibited maximum activity at 15oC and 35oC and that the activity was decreased at 40oC and totally lost at 55oC. AST activity was maximum at pH 7.4 in Tris-HCl buffer. Km values of AST for aspartate and 2-oxoglutarate were 1.64 mM and 2.2x10-2 mM, respectively, and Vmax values for the same substrates were 0.12 U/mL and 0.168 U/mL, respectively