Untersuchungen zur Thermostabilität immobilisierter Invertase

Invertase from baker's yeast (Saccharomyces cerevisiae) was covalently bound via glutaraldehyde to a macroporous polystyrene anion-exchanger, silica, and porous glass. The thermal stability of the enzyme-matrix complexes was found to be higher than that of soluble invertase, increasing in the order given above. The immobilization of invertase to the polystyrene anion-exchanger by benzoquinonen and trichlorotriazine provided enzyme derivatives with lower thermal stability compared to the soluble enzyme. The thermal inactivation of all invertase-matrix complexes is characterized by a biphasic course. The inactivation process is well described by a model of ULBRICH and SCHELLENBERGER [1] which is based on the assumption of two differently stable enzyme fractions each of which being inactivated by a first-order reaction. This model proved to be appropriate also for the description of the thermal inactivation in the presence of substrate.