Search

Despite the widespread use of sonication in medicine, industry, and research, the effects of sonication on proteins remain poorly characterized. We report that sonication of a range of structurally diverse proteins results in the formation of aggregates that have similarities to amyloid aggregates. The formation of amyloid is associated with, and has been implicated in, causing of a wide range of protein conformational disorders including Alzheimer's disease, Huntington's disease, Parkinson's disease, and prion diseases. The aggregates cause large enhancements in fluorescence of the dye thioflavin T, exhibit green-gold birefringence upon binding the dye Congo red, and cause a red-shift in the absorbance spectrum of Congo red. In addition, circular dichroism reveals that sonication-induced aggregates have high beta-content, and proteins with significant native alpha-helical structure show increased beta-structure in the aggregates. Ultrastructural analysis by electron microscopy reveals a range of morphologies for the sonication-induced aggregates, including fibrils with diameters of 5-20 nm. The addition of preformed aggregates to unsonicated protein solutions results in accelerated and enhanced formation of additional aggregates upon heating. The dye-binding and structural characteristics, as well as the ability of the sonication-induced aggregates to seed the formation of new aggregates are all similar to the properties of amyloid. These results have important implications for the use of sonication in food, biotechnological and medical applications, and for research on protein aggregation and conformational disorders.

Six polymeric stationary phases with various amine groups were prepared by surface grafting of glycidyl methacrylate on silica gel surface and its subsequent amination. The six kinds of amines, namely, triethylamine, diethylamine, ethylenediamine (EDA), hexaethylenediamine (HEDA), diethylenetriamine (DETA) and triethylenetetraamine (TETA) were used in this study. The separation of bovine serum albumin (BSA) and chicken egg albumin (CEA) on the polymeric stationary phase with various amines was investigated. The affinity degree of BSA was higher than CEA for the EDA, HEDA and DETA columns, whereas the affinity degree of CEA was higher than BSA for the TETA column.