Enzymes in polyelectrolyte complexes. The effect of phase transition on thermal stability.

摘要: Penicillin amidase, α-chymotrypsin and urease have been immobilized in water-soluble nonstoichiometric polyelectrolyte complexes (N-PEC). N-PEC are formed by modified poly(N-ethyl-4-vinyl-pyridinium bromide) (polycation) excess poly(methylacrylic acid) (polyanion). a new class of polymers capable, characteristically, phase transitions solution ⇄ precipitate induced slight change pH or ionic strength. Neither the chemical structure carrier nor number cross-linkages between an enzyme on transition. That gives unique opportunity to elucidate difference enzymes water-insoluble supports. A detailed study transition effect thermal stability protein-protein interactions has carried out. The following effects were found. 1 Pronounced stabilization penicillin amidase may be achieved two conditions: (a) is precipitate; (b) the-enzyme linked nucleus. Then N-PEC-bound increases 7-fold at 5.7, 60°C, 300-fold 3.1, 25°C, compared native enzyme. For urease, 20-fold 5.0, 70°C. 2 The localization established titration bound polycation polyanion with basic pancreatic trypsin inhibitor. Both (pH 6.1) 5.7), molecule fully exposed solution. If polycation, only 20% molecules 40% retain their ability for interactions. This means that polycation-bound localized hydrophobic nucleus complex, whereas polyanion-bound sits hydrophilic shell complex. 3 On pH-induced decreases from 6.1 there occurs stepwise decrease activity which due 9.8-fold increase Km 2-nitro-4-phenylacetamidobenzoic acid. 4 Change catalytic reversible reproducible. Such soluble-insoluble controllable used simulating events vivo biotechnology.