Effects of Plasma-Generated Long-Lived and Short-Lived Reactive Oxygen and Nitrogen Species on Protein Structures

The aim of this study is to investigate the impact of long-lived and short-lived reactive oxygen and nitrogen species (RONS) generated by cold atmospheric plasma on protein. In contrast to existing research primarily focusing on the effects of RONS on proteins, this study emphasizes the clarification of the effects of long-lived and short-lived RONS on proteins and potential subsequent impacts on cells. Through both direct and indirect plasma treatment, we compared the effects of long-lived and short-lived RONS on proteins and observed protein structural changes using techniques such as gel electrophoresis and Western blotting. The results indicate that peptide bonds and intramolecular disulfide bonds in proteins remain intact, but the binding affinity of TNF-α with antigens decreases. Since both methods of application resulted in decreased binding affinity, it is inferred that long-lived RONS are the primary cause. In summary, the RONS generated by the plasma jet used in this study (H₂ O₂ concentration of 867 μM, ·OH concentration of 60 μM) did not alter protein structures. Furthermore, when compared to other studies on cancer cell apoptosis, the RONS concentration in this study was higher, but protein structure remained unchanged. Therefore, it is suggested that RONS do not induce cell apoptosis through the direct disruption of protein structures.