Extracellular deamination of L-amino acids by Chlamydomonas reinhardtii cells.

When grown in the light and in a Tris-acetate phosphate medium, cells of Chlamydomonas reinhardtii Dang. can use the following L-amino acids as a sole nitrogen source: asparagine, glutamine, arginine, lysine, alanine, valine, leucine, isoleucine, serine, methionine, histidine, and phenylalanine, whereas, in the absence of acetate, the cells only used L-arginine. The utilization system in the acetate medium consisted of an extracellular deaminating activity induced by L-amino acids; it took between 10 to 30 h before the system appeared in cells previously grown with ammonium. This deaminase activity was nonspecific, required an organic carbon source for its de-novo synthesis, and was sensitive to high ammonium concentration and light deprivation.