Coomassie Brilliant\nBlue Induces Coiled-Coil Aggregation\nin Lysozyme at pH 7.4 by Hydrophobic and Electrostatic Forces

Several neurodegenerative\ndiseases are associated with\nthe deposition\nof amyloid fibrils. Although these diseases are irreversible, knowing\nthe aggregation mechanism is useful in developing drugs that can arrest\nor decrease the aggregation rate. In this study, we are interested\nin investigating the effect of Coomassie brilliant blue (CBB G-250)\non the aggregation of hen egg white lysozyme (HEWL) at pH 7.4. Various\nbiophysical techniques have been used, such as turbidity, Rayleigh\nlight scattering (RLS) kinetics, far-UV circular dichroism (CD), field\nemission scanning electron microscopy (FESEM), and transmission electron\nmicroscopy (TEM) imaging. The turbidity data indicated that CBB (≥0.1\nmM) induces aggregation in HEWL at pH 7.4. The aggregation kinetics\ncaused by CBB are quick without a lag phase and are dependent on the\nCBB concentration. The far-UV CD data revealed that the CBB-induced\naggregated samples had lost their CD signals without exhibiting a\nshift in the spectrum position. Sodium chloride and ammonium sulfate\nshow little effect on the CBB-induced aggregates, but alcohol such\nas methanol, ethanol, and 2-propanol could reverse the aggregation.\nOverall, this study aims to better understand the mechanism underlying\nCBB-induced aggregation and keep in mind that CBB employed in laboratories\ncan alter the protein structure. We report the aggregation of a natural\nprotein due to coiled-coil formation induced by a dye at physiological\npH and temperature conditions. This finding has high value because\nseveral dyes are used for diagnostic and therapeutic purposes, and\ncoiled-coil formation is closely related to infection mechanisms and\nnanoparticle-based drug deliveries.