[The distribution pattern of phosphoenolpyruvate-carboxykinase and ribulose-1,5-diphosphate carboxylase activities in fronds of Laminaria hyperborea (Gunn.) Fosl].

High activities of phosphoenolpyruvate-carboxykinase (EC 4.1.1.32) have been found in fronds of the brown alga Laminaria hyperborea (Gunn.) Fosl. The distribution pattern of this enzyme in the newly formed and in the old phylloid (last year's production) and in the cauloid was investigated and compared with that of ribulose-1,5-diphosphate carboxylase (EC 4.1.1.39). Maximum activity of both enzymes is located in the growing region of the new phylloid. In the other parts of the frond, enzyme activity is only about one tenth of the values estimated for the intercalary meristem. The activity of PEP-carboxykinase: RuDP-carboxylase shifts from approxymately 9 in the growing region to only 3 in the old phylloid.