A joint research group of Osaka University and Hokkaido University has succeeded in directly observing the phenomenon in which salts that should have been dissolved in a solution repeatedly precipitate and dissolve locally with a special electron microscope.Furthermore, we have succeeded in directly observing for the first time in the world how this phenomenon accelerates the formation of protein aggregates that cause Alzheimer's disease.
The concentration of solute in a saturated solution is called solubility.Even if the salt is dissolved in water, the salt does not precipitate if the concentration is below this concentration.In this experiment, a nano-sized region in the solution was observed with a special transmission electron microscope that can directly observe the liquid using a solution of salt having a concentration of about 50/1 of the solubility.Then, I discovered a phenomenon in which the salt that should have been dissolved occasionally precipitates and grows, shrinks within a short period of time, and dissolves again.This is a phenomenon in which when salt precipitates in a high-concentration region due to local fluctuations in concentration, the surrounding concentration decreases and contracts again.
The research group also found that this phenomenon accelerates protein aggregation.When the causative protein "amyloid β" of Alzheimer's disease is dissolved together with a salt, when the salt temporarily precipitates and grows, many protein molecules are adsorbed on the surface.It was then found that when the salt melted again, the adsorbed protein molecules were collected at the vanishing point of the salt and locally concentrated, resulting in the formation of protein aggregation nuclei (toxic aggregates).
Like amyloid β, proteins involved in neurodegenerative diseases have hydrophobic sites.The newly clarified agglutination mechanism is considered to be a phenomenon common to the onset of neurodegenerative diseases.In addition to elucidating the onset mechanism of Alzheimer's disease, it is expected to contribute to the prevention and treatment of neurodegenerative diseases.
Paper information:[The Journal of Physical Chemistry Letters] Time-Resolved Observation of Evolution of Amyloid-β Oligomer with Temporary Salt Crystals
