Detection of toxic metal ions in water based on Na+/K+-ATPase activity measurement

Abstract

The possibility of using enzyme Na+/K+-ATPase as a biological component of sensing system for detection of toxic metal ions (Hg2+, Pb2+ and Cd2+) in water samples has been studied. The method is based on the spectrophotometric determination of inorganic orthophosphate (P) that serves as a measure of the enzymatic activity in the presence of considered metal ions. The concentration of Pi, liberated by enzyme catalysed hydrolysis of adenosinetriphosphate (ATP), was followed spectrophotometrically, by single exposure to analytes or in the mixture. Hg2+, Pb2+ and Cd2+ induced the dose-dependent inhibition of Na+/K+-ATPase activity in enzymatic mixture. Sigmoid shaped inhibition curves were obtained in all cases. Half-maximum inhibitory activities (IC50) were determined by fitting the experimental data by sigmoid function. Considering Na+/K+-ATPase high sensibility to toxic metal ions, the development of simple and quick method for preliminary detection of water contamination by metals based on enzymatic activity measurement was suggested.