Ascorbate Peroxidase in Malted Barley

摘要

An ascorbate peroxidase has been identified in the acrospire and aleu-rone of germinating barley. Its synthesis is triggered in the aleurone by the presence of ascorbic acid and hydrogen peroxide. It has a relative molecular weight of 23,000-26,000 and a broad pH optimum, with 70% minimum of maximal activity over the pH range 5-7. However, it is relatively sensitive to heat, losing 50% of its activity in 30 minutes at 40°C. The enzyme has a very high affinity for hydrogen peroxide.