Application of MALDI-TOF mass spectrometry for study on fibrillar and oligomeric aggregates of alpha-synuclein

Aim. To study the -synuclein (ASN) aggregates of different structural origin, namely amyloid fibrils and spherical oligomers, in comparison with a native protein. Methods. MALDI TOF mass spectrometry and atomic for- ce microscopy (AFM). Results. The mass spectra of native and fibrillar ASN have similar character, i. e. they are characterized by the well pronounced peak of protein molecular ion, the low molecular weight associates, and rather low contain of fragmentation products. The spectrum of oligomeric aggregate is characterized by the high contain of fragmentation products, low intensity of protein molecular ion and the absence of peaks of associates. Conclusions. The difference between the spectra of fibrillar and oligomeric ASN could be explained, first, by the different content of the «residual» monomeric ASN and the protein degradation products in the studied samples, and, second, by the different structure-depended mechanisms of the protein degradation induced by the laser ionization. We suggested that the MALDI-TOF mass spectroscopy is a method useful for the investigation of ASN aggregation and characterization of its high order self-associates; besides, there is an interest in estimating the potency of the MALDI-TOF for the analysis of aggregation of various amyloidogenic proteins.

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