In this study, the fibrillation of hen egg-white lysozyme (HEWL) in the absence and presence of different concentrations of silybin was studied by thioflavin T spectroscopy, Congo red binding assays, 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence assay, circular dichroism, and transmission electron microscopy. The experimental results indicated that not only the fibrillation of HEWL at high temperature (65°C) and low pH (pH = 2.0) could be inhibited effectively by silybin but also the inhibition of HEWL by silybin followed a dose-dependent manner. Molecular docking studies indicated that 2 possible binding modes could be found in the interaction between silybin and HEWL via van der Waals forces and electrostatic forces as well as hydrogen bonding. One of these 2 conformations was directly entered into the cavity of HEWL (binding site I); the other was bound to the surface of HEWL (binding site II). In this way, silybin could not only increase the hydrophobicity of the cavity or the surface of HEWL but also influence the microenvironment of the binding site, which was able to stabilize the structure of HEWL and delay the process of HEWL fibrosis.
Peng Chen,Lancheng Wang,Dandan Xue,Mingjie Xu,Chi Hu
Split aptamers (SPAs) display unique functions to bind one another in the presence of a specific small-molecule or protein target, thus recognised as compelling tools in diagnostics and therapy. However, only a limited number of SPAs have been proven successful so far due to the largely compromised affinity, specificity and stability arising from cleaving a long parent aptamer. To this end, we propose a supramolecular anchoring approach to improve SPA function after the Systematic Evolution of Ligands by Exponential Enrichment process. With the macrocyclic host cucurbituril and its guest molecule tethered to separate strands of an SPA for the fluorescence dye Thioflavin T (TT), the anchoring module was constructed by host-guest complexation once TT was bound to the SPA and brought the discrete aptamer units into proximity. With the supramolecular anchor to facilitate the aptamer-target complex formation and stabilise the assembled structure via dynamic crosslinking, SPA function for bio-imaging and sensing purposes was largely improved as witnessed by the increased fluorescence readout of TT in the aptamer-bound form, even when the nucleic acid sequences were shortened below the duplex-formation level. The obtained fluorescence response tracked well with the anchoring strength (none, weak or strong), thereby validating the supramolecular entity as a sophisticated and versatile strategy to rehash the otherwise incompetent SPAs.
危险品化学品经营许可证（带存储）