Enhancement of Alpha-amylase's Stability and Catalytic Efficiency After Modifying Enzyme Structure Using Calcium and Ultrasound

High thermostability and catalytic efficiency of alpha-amylase are required for the industrial applications. To improve catalytic parameters including Michaelis constant, maximum velocity, turnover number, enzyme half-life, and the catalytic efficiency of alpha-amylase, it was treated alone and/or simultaneously with Ca2+ ions (12.5 and 25 mM) and/or ultrasound (USN) (64.5 W, 25 + 40 kHz). The structural analysis of the enzyme (the enzyme's secondary structure and conformation) was carried out using Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) techniques. Moreover, the thermal properties of the enzyme were evaluated using differential scanning calorimetry (DSC). USN + 12.5 mM Ca2+ and 25 mM Ca2+, changed the maximum velocity (+ 6.5% and + 37.4%), turnover number (+ 6.6% and + 38.2%), enzyme half-life (+ 51.6% and + 113.7%), and catalytic efficiency (+ 18.1% and -3.3%) of alpha-amylase. The energy barriers of thermo-inactivation and inactivation enthalpy of alpha-amylase exposed to USN + 25 mM Ca2+ were increased by 25% and 5.8%, respectively, without affecting entropy of inactivation, showing how enzyme's thermal stability was improved after the treatments. The increase in midpoint temperature (35%) and alpha-helix (14%) values as well as the decrease in the beta-sheet structure (39%) of the alpha-amylase after applying USN + Ca2+ (25 mM) confirmed the thermal stability enhancement of alpha-amylase after the treatment compared to control.

Automated summary

The use of Ca2+ ions and ultrasound treatment has been found to significantly improve the catalytic efficiency and thermal stability of alpha-amylase, leading to increased enzyme half-life and catalytic parameters.