Synthesis of double-fluorescent labeled prion protein for FRET analysis.

An abnormal form of prion protein (PrP) is considered to be the pathogen in prion diseases. However, the structural details of this abnormal form are not known. To characterize the non-native structure of PrP, we synthesized position-specific double-fluorescent labeled PrP for a fluorescence resonance energy transfer (FRET) experiment. Using FRET, we observed a conformational change in the labeled PrP associated with amyloid fibril formation. The FRET analysis indicated that the distance between fluorescent labeled N- and C-terminal sites of PrP increased upon the formation of amyloid fibrils compared with that of the native state. This approach using FRET analysis is useful for elucidating the structure of abnormal PrP.