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The amyloid fibrils derived from protein and peptide self-assembly have been studied in many diseases. In the present study, in combination with Thioflavin T(ThT) assay, Congo red(CR),transmission electron microscopy and cell cytotoxicity assay, we investigated the influence of zinc ions on amyloid fibril formation using hen egg white lysozyme (HEWL) as a model protein under high temperature and acidic pH conditions. We observed that HEWL tended to form the amyloid fibrils at pH 2.0 and 60 °C, which was consistent with the previous studies. However, as the concentrations of zinc ions increased, the amounts of amyloid fibrils of HWEL gradually reduced, but the overall morphology of individual amyloid fibril was not significantly altered whether or not zinc ions were present. Moreover, by using circular dichroism (CD), ANS and intrinsic fluorescence spectra, we illustrated that zinc ions inhibited the formation of β-sheet and exposure of hydrophobic regions of HEWL. This work would help to understand the molecular mechanism of amyloid fibril formation. [ABSTRACT FROM AUTHOR]

Abstract: β-Lactoglobulin (β-LG) is the major constituent of whey food, which has been shown to interact with a wide range of aroma compounds. In the present work, a model aroma compound, β-ionone, is used to investigate the influence of aroma compounds on the urea-induced unfolding of β-LG at pH 7.0. β-Ionone is observed to enhance the stability of β-LG at pH 7.0. Moreover, the amyloid fibrils are observed when β-LG at pH 7.0 is incubated for 12–20 days at 37°C in the presence of 3–5M urea. However, the formation of amyloid fibrils is inhibited when β-ionone is added into the samples and the inhibitory effects follow a concentration-dependent fashion. There is a clear correlation between C m and lag time. The correlation demonstrates that protein stability affects the amyloid fibril formation of β-LG. The results highlight the critical role of protein stability and provide an approach to prevent the formation of amyloid fibrils in vitro. [Copyright &y& Elsevier]

[Display omitted] • Clioquinol inhibits the fibril formation of hen egg-white lysozyme. • The binding between clioquinol and hen egg-white lysozyme prevents the exposure of hydrophobic regions. • Clioquinol retards the conversion of α-helix to β-sheet of hen egg-white lysozyme. Here, we reported the role of clioquinol in amyloid aggregation of hen egg white lysozyme (HEWL) under stressful conditions by several biophysical methods including thioflavin-T (ThT) fluorescence, Congo red (CR), circular dichroism (CD) and transmission electron microscopy. Our work showed that CQ inhibited the fibril formation of HEWL and the inhibitory effects depended on the concentrations of CQ. Furthermore, fluorescence spectra were used to study the conformation changes of HEWL caused by CQ. These data revealed that the interactions of CQ with HEWL changed the tertiary structure and inhibited the hydrophobic exposure of HEWL. [ABSTRACT FROM AUTHOR]