Study of the pseudoperoxidatic activity of soybean leghemoglobin and sperm whale myoglobin

The compound formation between soybean leghemoglobins a and c and H2O2 or ethyl hydroperoxide has been studied and compared with the hydrogen peroxide compound of sperm whale myoglobin. the titration data show that the hydrogen peroxide compounds of leghemoglobins are formed in a 1:1 molar ratio. The kinetics of the formation of the compounds follow first-order kinetics and the compounds are formed considerably faster than the myoglobin peroxide compound. The pseudoperoxidatic activity of leghemoglobins a and c and myoglobin was studied using guaiacol as electron donor. The maximal reaction velocities of leghemoglobins are greater than that of myoglobin. The results indicate that the peroxidatic activity of ferrileghemoglobin may be biologically important for instance in aging root nodules.