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

Area of Science:

• Biochemistry and Materials Science
• Enzyme Immobilization
• Polymer Chemistry

Background:

• Enzyme immobilization is crucial for industrial applications and studying enzyme behavior.
• Nonstoichiometric polyelectrolyte complexes (N-PEC) offer a novel platform for enzyme immobilization.
• Understanding enzyme behavior in soluble vs. insoluble immobilized states is essential.

Purpose of the Study:

• To immobilize penicillin amidase, alpha-chymotrypsin, and urease in water-soluble N-PEC.
• To investigate the effect of N-PEC phase transitions on enzyme thermal stability and activity.
• To determine enzyme localization within the N-PEC structure and its impact on interactions.

Main Methods:

• Formation of N-PEC using modified poly(N-ethyl-4-vinyl-pyridinium bromide) and poly(methylacrylic acid).
• Enzyme immobilization within the N-PEC matrix.
• Analysis of phase transition effects on enzyme thermal stability, activity, and protein-protein interactions via titration.

Main Results:

• Significant thermal stabilization of penicillin amidase (up to 300-fold) and urease (up to 20-fold) when immobilized in N-PEC precipitates.
• Enzyme localization determined: polycation-bound enzymes are in the hydrophobic nucleus, polyanion-bound enzymes on the hydrophilic shell.
• Reversible changes in penicillin amidase activity and stability observed upon pH-induced phase transitions.

Conclusions:

• N-PEC provide a versatile system for creating immobilized enzymes with tunable properties.
• Controlled phase transitions in N-PEC enable modulation of enzyme thermal stability and activity.
• This approach has potential for simulating in vivo processes and advancing biotechnological applications.