Abstract : Expression constructs have been prepared in order to generate the 89-143 fragment of the prion protein with isotopic labels using either in vitro translation or expression in E.coli cells. Initial testing of expression has been done. Conditions have been investigated for rapidly dissolving fibrils of PrP(89-143) and proteolytically fragmenting them for mass spectroscopic analysis to probe the extent of hydrogen exchange of backbone amides with deuterated water solvent. Conditions for complementary NMR analysis using organic solvent to dissolve the fibrils have also been investigated in a related model system, TTR. Solid state NMR measurements have been done with synthesized PrP(89-143) peptides incorporating specific 13C labels. These measurements probe the conformation around glycine residues in addition to several other backbone sites in the segment from residue 112 to 123. These measurements indicate that residues in this section of PrP(89- 143) are primarily extended beta structure in fibrils, though G113 may be less ordered or part of a turn.