The effect of chemical modification using citraconic anhydride on the stability of α-amylase from Aspergillus fumigatus

The purpose of this research is to improve the stability of α-amylase from Aspergillus fumigatus by chemical modification with citraconic anhydride. The α-amylase was isolated using a centrifugation technique, followed by purification using precipitation and dialysis of ammonium sulfate salt. The experimental results demonstrate that the stability of purified α-amylase is 13.41 times higher than that of the crude extract. A significant increase in the optimum temperature was also achieved, in which the optimum temperature of 50 °C was found for native α-amylase, while for modified α-amylase, the optimum temperature of 60 °C was found. Similarly, an increase in half-life was also evident, which is 38.72 min found for the native enzyme to 256.67–330.00 min for modified α-amylase, depending on the volume of citraconic anhydride used. Modification also resulted in increased free energy values (ΔG i) from 104.348 for the native enzyme to 109.585–110.281 kJ mol−1 for modified α-amylase, indicating that modified α-amylase is stiffer than native α-amylase. The results obtained in this work demonstrate that citric anhydride is a very promising modifying agent to improve the stability and performance of α-amylase enzyme isolated from A. fumigatus. The findings of this study also offer an opportunity for the application of citric anhydride for other enzymes.