Rhodanese Activity of Soils

Abstract

AbstractThe detection of rhodanese (enzyme catalyzes the formation of SCN‐ from S2O32‐ and CN‐) in soils is reported, and a simple method of assaying rhodanese activity in soils is described. This method involves colorimetric determination of the SCN‐ produced by rhodanese activity when soil is incubated with buffered (0.05M THAM, pH 6.0) S2O32‐ and CN‐ solutions and toluene at 37°C for 1 hour. The method developed is rapid, sensitive, and precise. The procedure used to extract SCN‐ stops rhodanese activity in soils and gives quantitative recovery of the SCN‐ formed. Results showed that steam sterilization and formaldehyde inhibit, sulfate and chloride activate, and toluene has no effect on rhodanese activity in soils. The initial rates of SCN‐ formation obeyed zero‐order kinetics; in one soil, the rate slowed with time of incubation. The temperature dependence of the rate constant conformed to the Arrhenius equation up to the point of enzyme inactivation (65°C). The activation energy of rhodanese activity of the eight soils studied ranged from 5,160 to 8,110 (avg. 6,690) calories/mole. Studies of other properties of rhodanese activity in soils are reported.