IMMOBILIZATION OF POLYPHENOL OXIDASE BY SOIL HUMUS

Humus preparations extracted from forest litter and soils by treatment with salt buffer solution were found to exhibit polyphenol oxidase ac tivity. The enzyme is present as a complex with humic substances, to w hich it is bound both by labile electrostatic bonds and by stronger bo nds. The enzyme is most strongly bound by the humic acids of horizon A l. The presence of clay minerals in the preparations suggested that th ey are an important component of the active organomineral complexes.