Metabolism and Physiological Function of L-Ascorbic Acid in Euglena gracilis

Abstract

Occurrence, metabolism and physiological functions of L-ascorbic acid have not been reported in Euglena gracilis, a flagelate protozoon. In view point of the unique phylogenetic position of Euglena, plant-like on one hand and animal -like on the other, elucidations of the pathway and subcellular distribution of L-ascorbic acid biosynthesis and of the physiological functions of the acid are highly interesting and might make contributions to understanding the functions of L-ascorbic acid in other organisms. The present review describes the biosynthesis of L-ascorbic acid, effect of light on the cellular acid content and disposal of peroxides by new L-ascorbic acid peroxidase in E. gracilis, with special emphasis on its role in protection of the cells from oxygen toxicity.