SEMINAR

Amorphous vs Amyloid Aggregation with the Effect of Heating

Abstract
As we know, aggregation of egg-white occurs upon heating. Similar to that case, protein aggregation has a tendency to be accelerated by heating. Protein aggregates can be classified into two types: one is amyloid fibril and the other is amorphous aggregate. Both types of aggregates are associated with various diseases. In a previous study, we reported with β2-microglobulin that the salt concentration-dependent formations of amyloid fibrils and amorphous aggregation occurred competitively [Adachi et al., JBC, 290, 18134 (2015)]. At high salt concentrations, amorphous aggregates were dominantly formed, whereas amyloid fibrils were formed at moderate salt concentrations. In order to further clarify the competitive mechanism of protein aggregation, we studied the effects of heating rate on the aggregation of β2-microglobulin, hen egg-white lysozyme and insulin. On the basis of the salt concentration-dependent aggregation, it was assumed that protein aggregation is controlled by the heating rate. Fibrillation experiments were performed while increasing temperature at various heating rate. At a high heating rate, no amyloid fibrils were detected and amorphous aggregates accumulated, whereas at a low heating rate, amyloid fibrils predominated. These results suggested that, because of a long lag time of fibrillation, amorphous aggregates which form without a lag phase accumulate at a high heating rate. The results support the competitive mechanism of amyloid fibrillation and amorphous aggregation.

BIOGRAPHY

2013-present: Institute for Protein Research, Department of Biological Sciences, Graduate School of Science, Osaka University

Research Fields and Interests:
I’m interested in the mechanism of protein aggregation. It is known that protein aggregates are associated with various diseases, such as Parkinson diseases, Alzheimer diseases, cataract, and so on. Therefore, to clarify the mechanism of protein aggregation is important for preventing and treating the diseases. We found that supersaturation plays important roles in protein aggregation and reported a competitive aggregation mechanism based on supersaturation. Furthermore, to reveal the generality of competitive mechanism, Now, I study the mechanism of protein aggregation with a focus on the heat effect.