Effects of recombinant α-syn oligomers on 20S proteasomal activity <i>in vitro</i>.

<p>To assess the effect of recombinant α-syn on 20S proteasomal activity a fluorogenic cell-free 20S proteasome assay was performed, implementing different α-syn preparations at various concentrations as well as a negative vehicle control and a positive lactacystin control. No or little inhibitory effect on the catalytic activity of isolated human 20S proteasomes was observed for all four α-syn oligomer preparations: (A) Kayed et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184040#pone.0184040.ref025" target="_blank">25</a>] (0.2 μM α-syn vs vehicle, p = 0.6008; 2.0 μM α-syn vs vehicle, p = 0.0405) (B) Lindersson et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184040#pone.0184040.ref021" target="_blank">21</a>] (30 μM α-syn vs vehicle, p = 0.8088) (C) Snyder et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184040#pone.0184040.ref022" target="_blank">22</a>] (0.3 μM α-syn vs vehicle, p = 0.4838; 3.0 μM α-syn vs vehicle, p = 0.0735; 30.0 μM α-syn vs vehicle, p = 0.0194) (D) Kostka et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0184040#pone.0184040.ref026" target="_blank">26</a>] (0.3 μM α-syn vs vehicle, p = 0.3167; 0.9 μM α-syn vs vehicle, p = 0.0603). All graphs display mean comparable relative fluorescence intensities (RFU) +/- SD, n = 3).