Fig. 1.

Cytosolic, multimeric brain-derived αS is helically folded and exhibits a mass of 86 kDa as demonstrated by circular dichroism spectroscopy (CDS) and multi-angle light scattering (MALS) analyses of purified αS^H and αS^U a Elution fractions 1–3 of a 2F12 anti-αS column incubated with a cross-linked control brain lysate showing the purification of the αS protein. On the right side, fractions 4–10 after size exclusion chromatography (SEC) are displayed showing the separation of αS^H and αS^U for downstream CDS and MALS analysis. b CDS of immunoprecipitated and separated (SEC) αS^H and αS^U from human frontal cortex control brain tissue upon cross-linking of brain lysate. The αS^H from human brain exhibits an α-helical secondary structure of ~ 50%. c CDS of recombinant αS from E. coli. The recombinant αS is unfolded (~ 5% helical fold, ~ 95% unfolded, monomeric). The unfolded structure of recombinant αS from E. coli remains after cross-linking (~ 5% helical fold, ~ 95% unfolded, monomeric). d CDS of purified, native αS^H from red blood cells (RBC) exhibits a secondary structure of ~ 45% helical fold and ~ 55% unfolded[4]. Cross-linked αS^H from HEK cells exhibits an α-helical secondary structure of ~ 48% helical fold and 52% unfolded. The cross-linked αS^H from human brain exhibits an α-helical secondary structure of ~ 50%. e Folded structure of αS without and with cross-linking demonstrating the difference from human and recombinant origin. f Immunoprecipitated αS^U from frontal cortex tissue of a control was separated from αS^H by SEC and analyzed via MALS demonstrating a mass of ~ 18 kDa. Immunoprecipitated αS^H from frontal cortex tissue of a control was separated from αS^U by SEC and analyzed via MALS demonstrating a mass of ~ 86 kDa