Polyamine Biosynthetic Enzymes in <italic>Chlorella</italic>: Characterization of Ornithine and Arginine Decarboxylase

Abstract

In a Chlorella culture grown asynchronously under autotrophic conditions, two biosynthetic enzymes of putrescine—ornithine decarboxylase (ODC) and arginine decarboxylase (ADC)—were detected. Both enzymes require pyridoxal phosphate and dithiothreitol for their activity but differ in their optimal pH, the ionic strength of their buffer, temperature of inactivation, and Km. In addition, L-canaline was found to inhibit the activity of ODC but not that of ADC. During the logarithmic phase of growth, ODC activity increased sharply, then decreased before the onset of the stationary phase. ADC activity changed only slightly during growth.