[Structural regulation by calcium ion in preparing cross-linked enzyme aggregates]

Area of Science:

• Biocatalysis
• Enzyme Engineering
• Materials Science

Background:

• Cross-linked enzyme aggregates (CLEAs) are widely used immobilization matrices.
• Controlling CLEA properties is crucial for optimizing enzyme performance.
• The influence of divalent cations on CLEA morphology and function requires further investigation.

Purpose of the Study:

• To investigate the effect of calcium ions (Ca²⁺) on the particle size and pore structure of glucose oxidase CLEAs.
• To evaluate the impact of Ca²⁺ on the activity and stability of glucose oxidase within CLEAs.

Main Methods:

• Preparation of glucose oxidase CLEAs with varying concentrations of Ca²⁺.
• Analysis of CLEA particle size and pore structure.
• Measurement of enzyme activity, substrate conversion, operational stability, and maximum reaction speed.

Main Results:

• Calcium ions significantly reduced CLEA particle size.
• Increasing Ca²⁺ concentration led to the disappearance of CLEA pore structures, with a definitive pore structure observed at 0.1 mmol/L Ca²⁺.
• CLEAs prepared with Ca²⁺ exhibited 1.69 times higher glucose oxidase activity compared to those without Ca²⁺.
• Enzyme activity remained 42% higher even at 1.0 mmol/L Ca²⁺.
• Ca²⁺-prepared CLEAs showed enhanced substrate conversion, operational stability, and increased maximum reaction speed.

Conclusions:

• Calcium ions are effective in improving the performance of glucose oxidase in CLEAs.
• The optimal Ca²⁺ concentration for preparing glucose oxidase CLEAs with improved properties is 0.1 mmol/L.
• Ca²⁺-mediated improvements in CLEA structure translate to enhanced biocatalytic efficiency and stability.