Ionic Requirements of Alginate-Modifying Enzymes in the Marine Alga Pelvetia canaliculata (L.) Dcne. et Thur.

Abstract
A stable, semi-pure, freeze-dried powder containing alginate 5-epimerase and alginate lyase activity was prepared from the marine brown alga P. canaliculata (L.) Dcne. et Thur. Maximal epimerase activity was at 3.4 mM and 100 mM for Ca2+ and Mn2+, respectively. Alginate lyase was activated by Ca2+ at 3.4 mM but was inhibited by Mn2+. An ion combination Ca2+/Mn2+ (3.4 mM/10 mM) was optimal for epimerization but inhibited lyase activity by 90% of that of Ca2+ alone. Increasing concentrations of substrate polymannuronate removed the lyase inhibition by Mn2+.