Assessing the impact of atmospheric cold plasma and microwave irradiation on activity, stability, kinetics, and...

Polygalacturonase hydrolyzes the α-(1-4)-glycosidic bonds present between the galacturonic monomers of the polygalacturonic acid chain by introducing water molecules across the oxygen bridge, which leads to pectin depolymerization. This comparative assessment reveals the impact of the atmospheric cold plasma and microwave irradiation on the activity, stability, kinetics, and structural changes of polygalacturonase. A 129 % and 193 % increase in relative activity was observed in the atmospheric cold plasma-treated and microwave-treated polygalacturonase at specified enzyme conditions. The reduction in free sulfhydryl groups enhances the formation of new disulfide linkages. An increase in UV-visible absorbance, tryptophan fluorescence, and surface hydrophobicity suggested tertiary structural changes. In addition, an increase in β-sheets and a reduction in α-helix were observed in both cold plasma and microwave treatment, β-sheets contribute to the catalytic efficiency of polygalacturonase. The peak intensity of infrared spectra of atmospheric cold plasma-treated and microwave-treated polygalacturonase decreased mainly due to structural changes in functional groups. An increase in protein aggregation and electrostatic interactions suggested the formation of new bonds, which stabilize the polygalacturonase structure that enhancing protein aggregation. The overall results concluded that both systems improve the characteristics of polygalacturonase. However, modification depends on the system parameters and characteristics of the enzyme.