EFFECTS OF ENVIRONMENTAL FACTORS ON OXIDIZING ENZYMES OF ROSE MALLOW SEEDS

Abstract

The power of plant tissues to break up hydrogen peroxide into water and molecular oxygen was known long before catalase was recognized as an enzyme, discovered, and named by Loew (18) in 1901. This discovery opened a new field for investigation and many studies were undertaken. The wide distribution of catalase in plant and animal tissue led Loew to conclude that it might serve as a protective measure against the injurious protoplasmic effects of hydrogen peroxide and possibly other related compounds formed in respiration. Dixon (8) has shown that when purine bases are oxidized by molecular oxygen in the presence of xanthine-oxidase as a catalyst, the oxidase undergoes destruction during the course of the reaction owing to the hydrogen peroxide that is formed. He found that this destruction could be prevented by the addition of catalase. Pneumococci in contact with a free supply of oxygen produced hydrogen peroxide in sufficient amount to inhibit their growth, but if catalase were added the bacteria grew vigorously. A close correlation between catalase activity and respiration was found in potatoes (2), in rice grains germinated under water (22), and in sweet corn (3). Crocker and Harrington (6) found this same correlation in the seeds of Johnson grass but not in Amaranthus. Rhine (26) using a number of different seeds concluded that catalase activity is a measure of the metabolic activity only when there is a rapid change in respiration. The absence of catalase activity in certain blue green algae (14) and in anaerobic bacteria (20) indicates that catalase is not essential to the respiration of all cells. McLeod and Gordon (20) consider it possible that catalase destroys some injurious substance such as H202 which is produced by aerobic organisms and by anaerobic organisms in the presence of oxygen ; thus anaerobic organisms lacking catalase would be injured when exposed to oxygen. A variation in catalase activity was observed by Pope (24, 25) in the different parts of the same barley plant. The relation of the catalase activity to physiological breakdown in Jonathan apples convinced Neller (23) that catalase activity could be used as a true index of the rate of metabolic activity. Heinicke (15,16) concluded that catalase activity is a highly sensitive index to changes in the internal condition of the apple tree, and that this activity varies with the season, with the part of the tree tested, and with