Inducible Formation of Urease in Canavalia ensiformis

Increase in urease activity in leaves of Canavdlia ensifomis has been demonstrated. The activity of excised leaves increased by about 100 percent when 1.5 × 10−1M urea was added externally as inducer. Glycine‐1‐14C was used to investigate whether the increase in activity was dependent on de novo protein synthesis. The Incorporation of labeled amino acid into urease was twofold higher in induced samples than in non‐induced ones. This indicates that the increase in activity is connected with de nova protein synthesis. The once increased activity was always followed by a rapid decrease. The urease activity was lost constantly with time after the external addition of ammonia in vivo. The inhibitory action of ammonia on urease fa vitro was eliminated by dialysis. Accordingly it may be concluded that the loss of activity was dependent on the product repression by ammonia.