The Discovery of the Effect of closo‐Borate on Amyloid Fibril Formation

Abstract

The activity of the boron cluster ‐ closo‐borates in protein amyloid fibrillization was first studied. For this, we explored the effect of dianionic compound [B12H12]2− on aggregation of amyloidogenic protein insulin by the circular dichroism spectroscopy, amyloid‐sensitive fluorescent dye based assay and transmission electron microscopy. It was shown that the presence of closo‐borate during fibrillization reaction speeds up the loss of the protein α‐helical structure. This effect of dianionic compound on protein fibrillization process is concentration‐dependent. Closo‐borate at low concentration (10 mM) enhances the intensity of insulin fibrillization, while at higher concentration (50 mM, 100 mM) fluorescent assay showed the decrease of this intensity. The morphology of fibrils formed in the presence of the boron dianion differs from that of free insulin, namely they are less branched and have the bigger diameter. Besides, closo‐borate‐induced fibrils have strong proneness to stick together forming large aggregated clots.

Inhibition of heat‐induced protein aggregation by zirconium phthalocyanines

“…Then, the samples were washed with distilled water and air‐dried. The stained samples were examined using JEM‐1400 TEM (Jeol, Japan) at 80 kV 18 . The length and diameter of the obtained products were estimated using the ImageJ program 19 …”

A Fluorescein-Substituted Perbrominated Dodecaborate Cluster as an Anchor Dye for Large Macrocyclic Hosts and Its Application in Indicator Displacement Assays

“…Recently, the supramolecular chemistry of dodecaborates has been intensively studied, in particular, their binding to water-soluble macrocyclic host molecules such as cyclodextrins, ,, cucurbiturils, and calixarenes . Moreover, biological interactions of dodecaborates with proteins, peptides, and membranes were also observed. − Much effort has been devoted to the synthesis and functionalization of the parent dodecahydro- closo -dodecaborate anion, B 12 H 12 2– , − allowing diverse applications in boron neutron capture therapy (BNCT), , drug delivery, and other related biological and medical fields. − However, perhalogenated decaborate and dodecaborate derivatives such as B 10 X 9 R 2– and B 12 X 11 R 2– (X = Cl, Br, or I), which are interesting due to their high thermal and redox stability, chemical inertness, superchaotropicity, and high membrane activity, , have received less attention in regard to their functionalization . However, the monoalkylation of B 12 X 11 OH 2– and B 12 X 11 NH 3 – clusters has recently been reported, − thus encouraging the development of synthetic methods for new derivatives, especially B 12 Br 11 OR 2– , to expand their host–guest chemistry and potential applications.…”