This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (14) Citing Articles via Google Scholar Google Scholar Articles by Ahmad, I. Articles by Hellebust, J. A. Search for Related Content PubMed PubMed Citation Articles by Ahmad, I. Articles by Hellebust, J. A. Agricola Articles by Ahmad, I. Articles by Hellebust, J. A.

Metabolism and Enzymology

Glutamine Synthetase Isoenzymes in the Green Soil Alga Stichococcus bacillaris Naeg. ¹

Department of Botany, University of Toronto, Toronto, Ontario, Canada M5S 1A1

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.