Extraction, Characterization and Inhibition Studies of Velvet Beans Urease Enzymes

Urease enzymes was extracted and studied for possible application as biorecognition element in electrochemical biosensors for heavy metal analysis in water matrix. This research work was based on the fact that heavy metal ions inhibit urease enzymes activity and the amount of inhibition is directly proportional to the concentration of inhibiting species in the sample. Urease enzymes activity and the effects of temperature, pH, enzyme/substrate concentration and incubation time on the urease activity was examined. Maximum urease activity of 10.230 U/mol was obtained at 40 oC and pH 7.5 with 220 µg/L enzyme concentration after 120 min incubation period. The Vmax and Km were estimated as 0.31 mM/min and 125 µg/L respectively. All of the heavy metals tested showed evidence of inhibition on the extracted urease enzymes, highest inhibition 80.541 was observed with Pb2+ and the lowest was 9.42 with Fe2+ meanwhile, no inhibition was observed with low concentration of Cr2+. This research revealed that Velvet beans urease enzymes can be used as biorecognition element in electrochemical biosensors for determination of heavy metal ions in water matrix. We therefore recommend for further electrochemical characterization with glassy carbon electrodes in electrochemical cells. Keywords: – Enzymes activity, Heavy metals, Biosensors, Biorecognition elements, Water matrix