Immobilization of Cellulase Using Polyurethane Foam
Cellulase was covalently immobilized using a hydrophilic polyurethane foam (Hypol FHP 2002). Compared to the free enzyme immobilized cellulase showed a dramatic decrease (7.5-fold) in the Michaelis constant for carboxymethylcellulose. The immobilized enzyme also had a broader and more basic pH optimum (pH 5.5-6.0) a greater stability under heat-denaturing or liquid nitrogen-freezing conditions and was relatively more efficient in utilizing insoluble cellulose substrates. High molecular weight compounds (Blue Dextran) could move throughout the foam matrix indicating permeability to insoluble celluloses; activity could be further improved 2.4-fold after powdering foams under liquid nitrogen. The improved kinetic and stability features of the immobilized cellulase combined with advantageous properties of the polyurethane foam (resistance to enzymatic degradation plasticity of shape and size) suggest that this mechanism of cellulase immobilization has high potential for application in the industrial degradation of celluloses.