The Molecular Biology of Euglena gracilis IX. Amino Acid Pool Composition

The amino acid composition of the acid soluble fraction of Euglena gracilis was determined from cells grown in 4 different culture media. Glutamic acid is the major free amino acid. Hydrolysis of this fraction increases the amount of free amino groups, the major amino acids found are then glutamic acid, aspartic acid, glycine and arginine. The pattern of amino acid distribution is similar in all 4 culture media. L-arginyl-L-glutamine was isolated and identified in extracts from all 4 culture conditions. It was shown to be a metabolic intermediate by radioactivity chase experiments.