Assessing the impact of pin-to-plate atmospheric cold plasma on activity, stability, kinetics, and conformation of α-amylase

Abstract

α-amylase is responsible for shortening the shelf life of food by degrading starch and glycogen into maltose, disaccharides, and oligosaccharides. This study focuses on the effect of atmospheric cold plasma on the activity, stability, enzyme kinetics, and structural change for its application in α-amylase modifications. A reduction in the residual activity from 96.01 % at 170 V to 88.01 % at 230 V after 12 min of treatment was observed in plasma-treated α-amylase compared to the untreated α-amylase at pH 5, 40 °C, after 120 min of reaction time using 2 g 100 mL−1 starch. An increased Km with a reduction in Vmax, kcat, and kcat/Km was observed with increasing voltage and treatment time. An increase in free sulfhydryl content, a decrease in tryptophan fluorescence, an increase in α-helix and β-sheet content, a decrease in β-turn and random coil structures, an increase in surface hydrophobicity, and protein aggregation indicate the structural changes of α-amylase were mainly due to the oxidative effects of reactive plasma species. No change in amide I, II, and III groups suggested plasma treatment did not alter the primary structure of α-amylase. The alteration in secondary, and tertiary structure after plasma treatment resulted in a loss of α-amylase activity.