Effects of Pulsed Electric Field (PEF) Treatment on Enhancing Activity and Conformation of α-Amylase

To explore an efficient, safe, and speedy application of pulsed electric field (PEF) technology for enzymatic modification, effects of PEF treatment on the enzymatic activity, property and kinetic parameters of alpha-amylase were investigated. Conformational transitions were also studied with the aid of circular dichroism (CD) and fluorescence spectra. The maximum enzymatic activity of alpha-amylase was obtained under 15 kV/cm electric field intensity and 100 mL/min flow velocity PEF treatment, in which the enzymatic activity increased by 22.13 +/- A 1.14 % compared with control. The activation effect could last for 18 h at 4 A degrees C. PEF treatment could widen the range of optimum temperature for alpha-amylase, however, it barely exerted any effect on the optimum pH. On the other hand, alpha-amylase treated by PEF showed an increase of V (max), t(1/2) and Delta G, whereas a decrease of K (m) and k were observed. Furthermore, it can be observed from fluorescence and CD spectra that PEF treatment had increased the number of amino acid residues, especially that of tryptophan, on alpha-amylase surface with enhanced alpha-helices by 34.76 % and decreased random coil by 12.04 % on alpha-amylase when compared with that of untreated. These changes in structure had positive effect on enhancing alpha-amylase activity and property.