TMAO and sorbitol attenuate the deleterious action of atmospheric pressure non-thermal jet plasma on α-chymotrypsin

Abstract

Enzymes exhibit a substantial degree of structural variability in the folded state and they are very sensitive to environmental changes. In order to investigate the effect of environmental changes on enzymes, we have studied the effect of cold atmospheric pressure plasma jets (APPJ) on α-chymotrypsin (CT). The APPJ consists of microdischarges, which are ejected from porous alumina through a 1 mm hole, reaching the CT samples and resulting in changes in the CT conformation. Furthermore, to gain insight into the contribution of the co-solvents, such as osmolytes (1 M trimethylamine N-oxide (TMAO), 1 M proline, 1 M betaine, 1 M sorbitol and 1 M glycerol) and the denaturant (1 M urea), on CT against the APPJ action, we monitored the associated structural changes in α-chymotrypsin (CT) using circular dichroism (CD), fluorescence and NMR measurements. Contrasting results are obtained from experimental data in the case of TMAO and urea, which allow us to infer that TMAO is able to attenuate strongly the deleterious action of APPJ on CT. Furthermore, the deleterious action of urea is enhanced in the presence of APPJ. The alterations in the secondary structure of this β/β protein, as quantified by the CD spectra, show reasonable enhancement for the β-strands in the presence of osmolytes as compared to buffer, even after the treatment with APPJ.