Singlet‐Oxygen‐Induced Phospholipase A₂ Inhibition: A Major Role for Interfacial Tryptophan Dioxidation

Abstract

Several studies have revealed that various diseases such as cancer have been associated with elevated phospholipase A 2 (PLA 2 ) activity. Therefore, the regulation of PLA 2 catalytic activity is undoubtedly vital. In this study, effective inactivation of PLA 2 due to reactive species produced from cold physical plasma as a source to model oxidative stress is reported. We found singlet oxygen to be the most relevant active agent in PLA 2 inhibition. A more detailed analysis of the plasma-treated PLA 2 identified tryptophan 128 as a hot spot, rich in double oxidation. The significant dioxidation of this interfacial tryptophan resulted in an N-formylkynurenine product via the oxidative opening of the tryptophan indole ring. Molecular dynamics simulation indicated that the efficient interactions between the tryptophan residue and phospholipids are eliminated following tryptophan dioxidation. As interfacial tryptophan residues are predominantly involved in the attaching of membrane enzymes to the bilayers, tryptophan dioxidation and indole ring opening leads to the loss of essential interactions for enzyme binding and, consequently, enzyme inactivation.

Insight into the Impact of Oxidative Stress on the Barrier Properties of Lipid Bilayer Models

“…As solely the effect on the major lipids of the membrane was investigated in this study, future efforts will include the analysis of oxidative stress impact on the functionality of membrane proteins as critical components of the cell membrane. A number of recent papers showed oxidative modifications in isolated proteins [ 26 , 77 , 78 ], suggesting that in the light of the current finding, a competitive situation may arise in a model containing both biomolecules impeding predictions. Tethered lipid bilayer membranes [ 79 ] and nanodiscs [ 80 ] are two approaches that enable the analysis of membrane proteins in a physiologically relevant environment possible.…”

Application of scanning electrochemical microscopy for topography imaging of supported lipid bilayers

“…27 Recently, we have studied the PLA 2 activity to damage the model lipid bilayer. 28 In this regard, the introduced method was employed to visualize the degradation of the lipid bilayer due to the action of PLA 2 . A solution of 10 −4 mg mL −1 PLA 2 in Tris buffer [0.010 M Tris (pH 8.9), 0.150 M NaCl, 0.005 M CaCl 2 ] was in contact with the lipid bilayer for four hours.…”

2022 Review of Data-Driven Plasma Science

“…Naturally, this affects all aspects of the topic, but the larger variance of biomedical experiments and the resulting data, and medical safety aspects accelerated the correspondent efforts. When surveying current publications on biomedical aspects of cold plasma, the use of bioinformatics tools has become the normal case [668][669][670]. Currently, when proteomics (proteins) or lipidomics (lipids) data are a central piece of the paper, most journals desire the upload of these data into public repositories to ensure their long-term persistence and preservation.…”

“…Via high-resolution mass spectrometry/bioinformatics and molecular dynamics simulation (GROMACS [56] program package (version 5.0) OPLS-AA/L all-atom force field), the amino acid residue tryptophan 128 was identified to be the target of plasma-derived singlet oxygen dioxidation, yielding a ring-open kynurenine derivative that subsequently distorted the secondary structure of the C-terminal β-sheets of PLA 2 (Fig. 42) [669]. In a similar manner, it was shown by Clemen et al in an animal model, that protein oxidation triggers a more strict response of the immune system, opening the avenue to plasma-driven cancer vaccination [668].…”