The Metabolism of Aromatic Compounds in Higher Plants VIII. ON THE REQUIREMENT OF HYDROXYNITRILE LYASE FOR FLAVIN

Abstract The hydroxynitrile lyases of etiolated sorghum seedlings and ground almonds have been purified to homogeneity as seen in the analytical ultracentrifuge. The sorghum enzyme preferentially catalyzed the dissociation of p-hydroxymandelonitrile, whereas the almond enzyme exhibited its maximum rate on mandelonitrile; p-hydroxybenzaldehyde and benzaldehyde, respectively, together with HCN, were the products of the reaction. The almond enzyme was found to contain a flavin prosthetic group and the sorghum enzyme did not. Physical and kinetic characteristics of the two hydroxynitrile lyases were compared and were found to be quite different.