Research of kinetics alaninaminotransferasе activities in potatoes

Aminotransferases (transaminases) catalyze intermolecular transfer of an amino group from amino acids on ketoacids, and as a coenzyme pyridoxal phosphate which carries out a role of an intermediate acceptor of an amino group serves in this reaction. For example, an alaninaminotransferase (AlAT) catalyzes reaction of transamination between alanine and α-ketoglutaric acid. Kinetic parameters of an alaninaminotransferase of potatoes are determined by Lineweaver-Burk plot: Km = 0.298 mmol/l, V max = 0.0151 µmol/min. The reduction of enzyme reaction rate under high concentration of a substrate was revealed. As extent of conversion of a substrate in a product doesn't exceed in our conditions 1%, it speaks about the phenomenon of inhibition by substrate. Using the assumption of formation of an inactive bisubstrate complex, we analysed the corresponding kinetic scheme for uncompetitive inhibition where the role of inhibitor plays a substratum, removed the equation Miсhaelis-Menten and Linewiever-Burk for this case and by differentiation defined the provision of a point of an extremum on Linewiever-Burk plot: : Ki = [ S ]2min / Km. It allowed to calculate an inhibition constant a substratum which is Ki = 0.428 mmol/l.