[Aspartate kinase activity of Cyanobacteria Anabaena variabilis].

Aspartate-kinase (ASK) activity of filamentous cyanobacteria A. variabilis and its dependence on physico-chemical factors and substrate concentration in the reaction mixture have been studied. Three isoenzymes ASK-1, ASK-2 and ASK-3 which differ in the values of pH-optima, molecular weight, isoelectric points and effector of retro-inhibition have been isolated by ion-exchange chromatography. High level of inhibition of summary ASK of the cell-free extract can be reached only in a case of simultaneous addition of all amino acids, the final products of this biosynthetic pathway into the incubation mixture.