Changes in the peroxidase activity of subcellular fractions from aging Phaseolus hypocotyls

Changes in nitrogen contents and peroxidase activities of fractions isolated from hypocotyl tissue of Black Valentine bean (Phaseolus vulgaris L.) of increasing age were studied. As beans aged in darkness, a decreasing percentage of their nitrogen content was recovered in the isolated particulate fractions. Peroxidase activity of particulate fractions from dark-grown beans accounted for 49% of the total activity of both 3-day-old seedlings and 16-day-old senescing plants. Peroxidase specific activity of dark-grown tissue homogenates did not increase with plant age; however, after a certain period of growth, further aging resulted in increased peroxidase specific activity associated with the particulate fractions. Between day 3 and day 8 the patterns of peroxidase activity of the different fractions varied, but over the period day 9 to day 16, the patterns of all fractions were correlated. The nitrogen contents and peroxidase activities of fractions isolated from beans transferred from dark to light were d...