THE OXIDASE OF THE APRICOT

Abstract

Supplementing the previous work of Samisch (1934) in this laboratory, an enzyme soln. free of catechol-like substances and containing an active peroxidase and an active phenolase was prepared from apricots. Peroxidase activity was measured by the depth of color developed by oxidation of guaiacol in the presence of H2O2 and that of phenolase by the color developed with guaiacol in the presence of catechol. The opt. pH range for peroxidase with guaiacol and H2O2 was 4.5-5.5 and for phenolase with catechol, 6.5-7; probably a function of the indicator rather than of the enzymes. The "death" temp for 5 min. heating for peroxidase was slightly above 90[degree]C at pH 5 and for phenolase slightly above 85[degree]C. Peroxidase in presence of H2O2 and phenolase in presence of catechol oxidized ascorbic acid. Both enzymes were completely inhibited by 0.01 [image] KCN; phenolase being somewhat less sensitive than the peroxidase. Other factors studied were effects of H2O2 concn., Fe, Cu, F, Cl, SO4, and C2O4 ions; sugar and dehydration on enzyme activity.