Parkinson's disease is the second most advanced neurodegenerative disease after Alzheimer's disease, and is accompanied by movement disorders due to limb tremor and muscle tension, which are more common in middle-aged and older patients.There is no radical cure and it is necessary to elucidate the onset mechanism.An abnormal protein aggregate called Lewy bodies is found in the patient's brain.It is said that α-synuclein, which is the main component, exists in the living body as a monomer (a structural unit of a polymer compound) or a tetramer (a combination of four monomers), and which structure is taken is the treatment. It has been regarded as important for legal development.However, since the studies so far have used recombinant proteins expressed in Escherichia coli, the structure in human organisms has been unclear.

　Therefore, the research group purified α-synuclein from human erythrocytes and used the small-angle X-ray scattering method at the large radiation facility SPring-8. It is a method to try structural analysis of α-synuclein by irradiating a solution close to the state in the living body with intense X-rays obtained by SPring-8 and measuring the one with a small scattering angle.

　Since this method requires a large amount of protein, we succeeded in the analysis by purifying a sufficient amount of α-synuclein with high purity from human erythrocytes.As a result, it was found that α-synuclein purified from human erythrocytes exists as a monomer having no specific structure.It was also suggested that some of them may exist as multimers depending on the solution conditions.

　This result will be useful information for the development of a radical treatment for Parkinson's disease, and it is expected that the onset mechanism will be elucidated in the future.