Dielectric barrier discharge plasma treatment affects stability, metal ion coordination, and enzyme activity of bacterial superoxide dismutases

Abstract

A molecular‐level understanding of the effects of atmospheric‐pressure plasma on biological samples requires knowledge of the effects on proteins. Superoxide dismutases, which detoxify superoxide under oxidative stress conditions, play akey role in bacterial plasma resistance. Investigation of the impact of dielectric barrier discharge (DBD) treatment on purified superoxide dismutases SodA and SodB of Escherichia coli showed that DBD treatment caused a rapid protein degradation, with only 8% of protein remaining after 10 min. The affinity of SodA for the metal cofactor Mn2+was reduced. Mass spectrometry, in conjunction with coupled‐cluster calculations, revealed that modifications of amino acid residues in the active site can explain the decreased metal affinity and a distortion ofthe coordination geometry responsible for the activity loss.

sponsible for the activity loss.