[Alanine dehydrogenase from the cyanobacterium Plectonema boryanum].

Alanine dehydrogenase activity of Plectonema boryanum cells was studied. It was found, that only NAD(H) may be used as the coenzyme. Kinetical parameters for substrates and coenzymes were determined. 2 pH-optima of action have been established for biosynthetic and anabolic reactions. Two isoenzymes of ADG were cleaned using the methods of ion-exchange chromatography and isoelectric focusing. Some physical-chemical properties were studied: pHopt--9-10 and 4.0; temperature optimum -40 degrees C; pI--8.2 and 6.4; molecular weight--50.65 and 52.48 kDa for ADG-1 and ADG-2, respectively. Both enzymes have the subunit structure. Every enzyme is composed by 4 identical polypeptides.