Preparation and characterization of urease bound on crosslinked poly(vinyl alcohol)

Various parameters such as type and concentration of crosslinking agent, enzyme concentration, pH of the coupling medium and coupling time were optimized for the immobilization of urease on crosslinked poly(vinyl alcohol). Immobilized urease was thoroughly characterized for pH, temperature, solvents and storage stabilities and these properties were compared with the free enzyme properties. The Michaelis constant (K-m) and maximum reaction velocity (V-max) were calculated from Lineweaver-Burk plots for both free and immobilized enzyme systems. The energy of activation (Delta E-a) and the thermoinactivation constant (K-i) were calculated from the effect of temperature study. The urease-(PVA-F)-system shows good retention of activity even after 6-7 cycles. (C) 1998 Elsevier Science B.V.