Investigating the effects of plasma pretreatment on the formation of ordered aggregates of lysozyme

We investigated the influence of plasma pretreatment on fibril formation and aggregation properties of lysozyme by using the Congo red binding assay, transmission electron microscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), far-ultraviolet circular dichroism, and 1-anilinonaphthalene-8-sulfonic acid (ANS) fluorescence spectroscopy. Our Congo red binding and transmission electron microscopy findings indicated that plasma pretreatment may suppress the formation of ordered fibrillar lysozyme aggregates. The inhibitory effect triggered by plasma pretreatment was observed to be positively correlated with the duration of plasma pretreatment. Compared to the untreated controls, our ANS fluorescence results suggested that fewer solvent-exposed hydrophobic clusters in lysozymes were formed upon pretreatment with plasma. Moreover, HEWL samples with and without plasma pretreatment showed considerably different molecular profiles. We believe the outcome from this work may not only help develop potential strategies for the attenuation of ordered protein aggregation, which is implicated in amyloid pathology, but also present a nice example of plasma-based medicine.