Abstract
Amyloid fibrils are associated with various diseases such as Alzheimer's disease and type II diabetes. Amyloid fibril formation consists of nucleation and growth. The nucleation process does not readily occur. Once the nucleus formed, however, subsequent growth proceeds rapidly. These characteristics of amyloid fibril formation are similar to those of the crystal growth of substances, where agitation of solution often accelerates the nucleation process. We found that ultrasonication is useful for inducing amyloid nucleation and thus the formation of fibrils. In other words, ultrasonication is effective in breaking the supersaturation of amyloidogenic proteins. This is likely true for crystallization of the native state of proteins. Taking advantage of the effects of ultrasonication, we develop several methodologies by which we monitor the supersaturation of protein solutions. Proteins also form amorphous aggregates distinct from ordered amyloid fibrils. We show that ultrasonication is also useful for distinguishing amorphous aggregates and amyloid fibrils. Taken together, ultrasonication will become a unique technology for characterizing various types of supersaturation of protein solution, leading to understanding the role of supersaturation in life.
