Glutamine Synthetase Isoenzymes in the Green Soil Alga Stichococcus bacillaris Naeg.

Abstract
Two forms of glutamine synthetase (GS1 and GS2) have been separated from cells of Stichococcus bacillaris by fast protein liquid chromatography. The activities of the two isoenzymes were influenced by the composition of the media employed; thiol reagents were essential for stabilizing GS2 but they suppressed GS1 activity. The activity of each isoenzyme was, therefore, determined following separate purification procedures. Growth conditions influenced both isoenzymes; GS2 showed maximum activity under photoautotrophic conditions, whereas GS1 showed maximum activity under heterotrophic conditions.