Mannuronan C-5 epimerase activity in protoplasts of Laminaria digitata

Research paper by Ruth S. Hagen Rødde, Kjetill Østgaard, Bjørn A. Larsen

Indexed on: 01 Jun '93Published on: 01 Jun '93Published in: Hydrobiologia


Biosynthesis of alginate in algae may be studied by following the cell wall regeneration of brown seaweed protoplasts in culture. The enzyme mannuronan C-5 epimerase will control the composition of the alginate being synthetized.Freshly isolated protoplasts from the thallus of young Laminaria digitata plants showed only low expression of this enzyme. However, after prolonged periods in culture, this activity increased 15-fold. The synthesis of C-5 epimerase by the protoplasts is probably essential for the formation of a new cell wall.After cellular disruption by osmotic shock and centrifugation, most of the epimerase activity resided in the pellet fraction. This may indicate that the enzyme is membrane associated.