[Some properties of beta-aspartate kinase from Micrococcus glutamicus-95 bacteria]

Kinetic and allosteric properties of beta-asparatatekinase from Micrococcus glutamicus-95 were studied. Coarse protein fraction, sedimented at 0.8 from saturated (NH4)2SO4, was used as an enzyme preparation. Curves of the dependency of the enzymatic reaction rate on substrate (L-aspartic acid and ATP) concentration were not found to be S-like. However, double reciprocal plotting of the data obtained revealed their deviation from the hyperbolic curve. The effect of amino acids (lysine, threonine, isoleucine, valine) on the activity of beta-aspartatekinase is studied. Lysine was shown to inhibit slightly beta-aspartatekinase, while threonine slightly activated it. Combined addition of both amino acids at a concentration of 1 mM resulted in the 50% inhibition. Isoleucine and valine activated beta-aspartatekinase and eliminated multivalent inhibitory effect of lysine and threonine. Interaction of isoleucine and lysine+threonine with beta-aspartatekinase was competitive with respect to L-aspartic acid and non-competitive in relation to ATP.