摘要：

We have determined the kinetics and stabilities of various humus-urease preparations, extracted and purified from soil (Ceccanti, Nannipieri, Cervelli and Sequi, 1977). Km, values of five different fractions in phosphate buffer ranged from 8 to 40 mM and were similar to those of urease extracted from various other sources. However, the optimal pH for urease activity of the soil fractions...

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