Inhibition behavior of acid phosphatase, phosphodiesterase I and adenosine deaminase as tools for trace metal analysis and speciation

Simple inhibition tests are described for acid phosphatase, phosphodiesterase I and adenosine deaminase. From 23 different metals tested, the following ions affect the enzymes' activity (detection limits in 0.5 ml synthetic solution): inhibition of acid phosphatase: Hg 2+ (0.1 mg/l) and Cu 2 + (0.7 mg/l), inhibition of phosphodiesterase I: Be 2+ (8 μg/l) and Cd 2+ (0.9 mg/l), activation of phosphodiesterase I: Mg 2+ (3 mg/l) and Zn 2+ (2 mg/l), inhibition of adenosine deaminase: Hg 2+ (25 μg/l), Cu 2+ (70 μg/l) and Co 2+ (0.8 mg/l), respectively. For phosphodiesterase the interfering effect of inhibition and activation has been investigated. In a surface water sample, matrix effects caused by complexing agents in the organic matrix suppress the inhibition. In addition to the determination of total concentrations by instrumental analysis these effects may be used for evaluation of toxic effects and speciation of the trace elements mentioned above.