“…The former also inactivated (in 20 h) 30Zo more of an added.acid phosphatase preparation than did the latter. Also Kretschmer and Forsee 1954;Szalay et al 1975). This practice is interesting because of the property of heavy metals such as Cu for precipitating and thus inactivating enzymes and other proteins (Bowen 1966)' Enzymes accumulated in soils, perhaps through stabilization by quinone polymers (Burns er aI.…”