Understanding the impact of atmospheric cold plasma (ACP) on the activity, stability, kinetics, and structural properties of papain
摘要
The impact of atmospheric cold plasma (ACP) on papain’s activity, enzymatic parameters, and structural changes was studied at 170 V to 230 V from 5 to 20 min. The result suggested that papain was well stabilized at pH 8, 85 °C, using a 3 g/100 mL casein concentration after 60 min of reaction, and an inactivation was noted in ACP-treated papain compared to untreated. A reduction in residual activity, Vmax, km, kcat, and an increase in kcat/km of ACP-treated papain as the voltage and treatment time increased compared to untreated papain. An alteration in the chemical shift of the amide I bond and breakage of the amide III bond, an enhancement in β-sheet, and a reduction in α-helix, turns, and random coils alter the papain’s structure. An alteration in Trp fluorescence and a decline in extrinsic fluorescence of ACP-treated papain suggested reactive plasma species promoting oxidative effect leading to amino acid modifications, and breakage of covalent and non-covalent interactions present in papain. A decline in free sulfhydryl content and S–S vibrations suggested partial denaturation and folding of ACP-treated papain. The results concluded that low-voltage ACP alters the primary, secondary, and tertiary structure of papain, which negatively affects papain’s activity.