Unraveling the molecular mechanism of the effects of sodium dodecyl sulfate, salts, and sugars on amyloid fibril formation in camel IgG

Publication date: 1 October 2018Source: Colloids and Surfaces B: Biointerfaces, Volume 170Author(s): Mohamad Alhasan Ismael, Javed Masood Khan, Ajamaluddin Malik, Mohammad A. Alsenaidy, Syed Hidayathulla, Rizwan Hasan Khan, Priyankar Sen, Mohammad Irfan, Abdulrahman M. AlsenaidyAbstractSodium dodecyl sulfate (SDS) is an anionic surfactant that can be used to stimulate protein fibrillation in vitro. Here, we investigated the effects of SDS on camel IgG aggregation at pH 3.5 and 7.4. SDS-induced amyloid fibril formation in camel IgG was examined by turbidity measurements, Rayleigh scattering, Thioflavin T (ThT) fluorescence, intrinsic fluorescence, circular dichroism (CD), and transmission electron microscopy (TEM). The results suggest that low SDS concentrations (0.2–2.0 mM) induce amyloid-like aggregates of camel IgG at pH 3.5, indicating an SDS/camel IgG ratio below 1000. However, in the presence of higher concentrations of SDS (2.5–10.0 mM), amyloid fibril formation was not observed. Furthermore, at the higher concentrations, the β-sheet structure of camel IgG was transformed into a α-helical structure. The amyloid fibril formation was not observed in the presence of SDS at pH 7.4. Additionally, the role of salts and sugars was evaluated in the SDS-induced aggregation process. Interestingly, in the presence of 0.15 N of NaCl and (NH4)2SO4, SDS promoted camel IgG aggregation up to very high concentrations of SDS (0.2–10.0 mM; SDS/camel IgG ratio, 95–4750) a...

Source: Colloids and Surfaces B: Biointerfaces - July 5, 2018 Category: Biochemistry Source Type: research