Nachweis von Enzymen des Galactosestoffwechsels in der Grünalge Acetabularia mediterranea

Abstract

The reason for interest in the galactose metabolism of the unicellular green alga Acetabularia mediterranea lies in the question of how the different galactose content in the cell wall of the stalk and the cap is formed. The galactose content is low in the cell wall of the stalk and high in the membrane of the cap (Werz, 1963). Progress in this question presupposes information about the enzymes of galactose metabolism in this organism. The occurrence of the whole series of enzymes which are concerned with the synthesis of UDP-galactose from fructose-6-phosphate could be demonstrated. These enzymes are as follows: Phosphoglucose-isomerase [E.C.5.3.1.9], phosphoglucomutase [E.C.2.7.5.1], UDP-glucose pyrophosphorylase [E.C.2.7.7.9], UDP-glucose-4-epimerase [E.C.5.1.3.2], nucleosidediphosphate kinase [E.C.2.7.4.6] and inorganic pyrophosphatase [E.C.3.6.1.1]. In der einzelligen Grünalge Acetabularia mediterranea konnten die für die Synthese von UDP-galactose aus Fructose-6-phosphat notwendigen Enzyme Phosphoglucose-Isomerase, Phosphoglucomutase, UDP-glucose-Pyrophosphorylase und UDP-glucose-4-Epimerase nachgewiesen werden, außerdem Nucleosiddiphosphat-Kinase und anorganische Pyrophosphatase. Der Galactosestoffwechsel von A. mediterranea ist deshalb von Interesse, weil Stiel- und Hutmembran einen unterschiedlichen Galactosegehalt aufweisen.