Particle density estimation for HY assuming a four-rung β-solenoid structure.

The R_h of particles was calculated from DLS measurements. The length of the particles was calculated fitting the MALS measurements to a rod-shape model. The number of PrP monomers per PrP^Sc particle was estimated from the PrP^Sc particle length, assuming a contribution of 1.92 nm in length per PrP monomer and a PrP^Sc fibril formed by two protofilaments. The PrP normalized intensity was determined by immunoblotting using Sha31 antibody. The relative number of PrP^Sc particles was calculated by dividing the PrP normalized intensity by number of PrP monomers per PrP^Sc particle. The maximum possible PrP^Sc particle density was calculated with ASTRA software (see methods) for fractions 46 and 48, and extrapolated to the rest of the fractions based on the relative number of PrP^Sc particles. (*) these values of particle density were calculated from MALS measurements directly, fitting the data to a rod-shape model, and assuming a rod radius of 5.5 nm. This calculation was performed for all samples; the specific values obtained for brain E are shown in the table.

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