Michaelis constants of soil enzymes |
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| Authors: | MA TabatabaiJM Bremner |
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| Institution: | Department of Agronomy, Iowa State University, Ames, IowaUSA |
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| Abstract: | Studies to determine the Michaelis constants (km values) for the arylsulfatase and phosphatase activity in Iowa surface soils showed that the value obtained for either activity was different for different soils. When the incubation technique used to determine km did not involve shaking of the soil-substrate mixture, the km value for arylsulfatase activity in nine soils studied ranged from 1·37 × 10−3m to 5·69 × 10−3m, and the km value for phosphatase activity ranged from 1·26 × 10−3m to 4·58 × 10−3m. Shaking the soil-substrate mixture during incubation decreased the km value obtained for arylsulfatase or phosphatase activity and reduced the variation in km among soils. The maximum enzyme reaction velocity (Vmax value) for soil arylsulfatase or soil phosphatase activity was markedly different for different soils and usually increased when the soil-substrate mixture was shaken during incubation. The km value for soil arylsulfatase or soil phosphatase activity was not significantly correlated with other soil properties studied (pH, cation-exchange capacity, percentage organic carbon, percentage clay, percentage sand). |
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