Table 1.

N termini of PK-resistant cores of rPrP-res^RNA and rPrP-res^RNA-low as determined by mass spectrometric analysis of N-terminal tryptic fragments in PK-digested aggregates

Rugged N termini were observed for both rPrP-res^RNA and rPrP-res^RNA-low. The common C-terminal residue Lys-105 represents the most N-terminal trypsin cleavage site of PK-resistant cores (see “Experimental procedures”).

Aggregate type	N-terminal tryptic fragments	Relative amount (%)a
	81–105	23
rPrP-resRNA	89–105	43
	97–105	10
	99–105	93
rPrP-resRNA-low	100–105	4
	101–105	2

^a Estimate based on relative areas in chromatographic peaks.