Amino functionalization of carboxymethyl cellulose for efficient immobilization of urease.

Jack bean urease (EC.3.5.1.5) was effectively immobilized onto amino functionalized epichlorohydrin cross-linked carboxymethyl cellulose (ECH-CMC) beads that were fabricated by graft co-polymerization of polyacrylamide (PAm) onto ECH-CMC beads in presence of potassium persulfate (KPS)/thiourea (TU) combined redox initiator followed by Hoffmann degradation. The progress of the synthesis along with immobilization processes was investigated by FTIR spectra. Also, the morphological structures of the beads before and after urease immobilizations were examined using SEM. Immobilization efficiency and immobilized urease amounts were estimated as a function of the amino functionalization degrees. The effects of pH and temperature on urease activity were studied. The results showed that after immobilization the optimum pH and temperature displayed higher shifts to 8 and 45°C, respectively, which reveal a higher structural stability upon immobilization performance. Moreover, the kinetic studies indicated that the urea hydrolysis reaction, which catalyzed by urease enzyme displayed a good fit with Michaelis-Menten equation, and the kinetic parameters Km and vm were estimated to be 14±0.7mM and 2±0.2μmolNH3/min·mg immobilized urease, respectively. Furthermore, the immobilized urease maintained approximately 88% of its initial activity after the 10th reuse cycle.