FIG. 2.
Determination of arginase-specific activity and cytosolic and vacuolar glutamate, glutamine, arginine, ornithine, and lysine pools upon nitrogen starvation. Arginase-specific activity was measured in extracts from wild-type strain Σ1278b after growth on M.ammonia (time zero) and shifted to minimal medium without a nitrogen source (times 20, 40, 60, and 120 min) (A). The specific activity is expressed in micromoles of urea produced per hour per milligram of protein. (B to F) Solid diamonds, vacuolar amino acid pool; open circles, cytosolic amino acid pool. Amino acid intracellular concentrations are expressed in nanomoles per milligram of dry weight.