Contributors:Svetlana Sorokina, Vladimir Muronetz, Yulia Stroylova, Zinaida Shifrina, Sofya Tishina
The study describes the ability of cationic pyridylphenylene dendrimers of the second (G2), third (G3) and fourth (G4) generations to efficiently suppress the amyloid transformation of full-length ovine prion protein. The dendrimers are able to inhibit both the formation of the most toxic soluble oligomers and amyloid fibrils. monitor the secondary structure changes of PrP during oligomerization in the presence of dendrimers, circular dichroism spectroscopy (CD) was performed. CD molar elipticity.opj file collects raw circular dichroism data of the structures obtained when prevented prion protein oligomer formation by the dendrimers. Conversion CD to molar elipticity.xlsx file provides the information about molar elipticity calculation. The data show the formation of beta-sheet structure after incubation of PrP at 65 °C for 150 min without dendrimers, while addition of the dendrimers resulted in the mixed α/β structure.
The formation of protein oligomers was monitored by dynamic light scattering (DLS). Sorokina_oligomers_dls.dts file consists of raw dynamic light scattering data to be opened in Zetasizer Software. The analysis revealed the formation of PrP oligomers of 21 nm in size, while a clear decrease in particle sizes was observed for G3.
An absence of the conversion capacity of PrP-dendrimer complexes obtained when prevented amyloid fibril formation was tested using amyloid seeding assay. For the goal, the complexes resulted in the process of inhibition of amyloid fibril formation by the dendrimers were separated and thoroughly washed from the mixture and added as a seed to the native PrP. Seeding raw data.xslx file summarizes the raw thioflavine T fluorescence data and seeding.opj file represents the statistic calculation. It can be seen that even at low concentrations of 5 and 10 μM dendrimers significantly decrease the fluorescence intensity in comparison with that of the control. The highest impact was observed for G4 that inhibited the process at a concentration of 1 μM. The observations indicate the absence of conversion capacity in the protein-dendrimer complexes as they did not induce the conversion of the native PrP into abnormal form.