Investigation of Activity, Stability, and Structural Changes of Aspergillus Oryzae α-Amylase in the Presence of Water 1-Ethyl-3-methylimidazolium Acetate Mixture

Farahmand, Reza; Ebrahimi, Mehdi

Investigation of Activity, Stability, and Structural Changes of Aspergillus Oryzae α-Amylase in the Presence of Water 1-Ethyl-3-methylimidazolium Acetate Mixture

Document Type : Article

Authors

Reza Farahmand ¹
Mehdi Ebrahimi ²

¹ Department of Biology, College of Biological Sciences, Varamin-Pishva Branch, Islamic Azad University, Pishva, Iran

² Department of Biochemistry and Biophysics, College of Biological Sciences, Varamin-Pishva Branch, Islamic Azad University, Pishva, Iran

Abstract

α-Amylases catalyze the hydrolysis of starch and are widely used in various industries, especially in the food industry. Despite the high demand for the use of α-amylase in various industries, most α-amylases do not have the temperature and pH stabilities for use in industrial processes. Ionic liquids are broadly used as co-solvents to improve the activity, stability, and selectivity of enzymes. In this study, the effect of 1-Ethyl-3-methylimidazolium Acetate on the activity, temperature and pH optimum, thermal stability, and structure of an α-amylase from Aspergillus oryzae were investigated. The activity of α-amylase was decreased with increments in [EMIm][Ac] concentration. Vm of α-amylase in the presence of [EMIm][Ac] was increased while Km was decreased. Same as the absence of [EMIm][Ac], the optimal pH and temperature in the presence of [EMIm][Ac] were 7.5 and 45 °C, respectively. The inactivation rate of α-amylase at temperatures of 40, 50, and 60 °C in the presence of both 0.4 and 1 M [EMIm][Ac] is less than in its absence. Intrinsic fluorescence spectroscopy revealed structural changes in the presence of [EMIm][Ac]. These results indicate the improvements in the activity, optimum temperature, and thermal stability of α-amylase due to the structural changes induced with [EMIm][Ac].

Graphical Abstract