FTIR study on thermal denaturation and aggregation of recombinant hamster prion protein SHaPrP 90–232

Abstract

We have investigated the temperature induced denaturation and aggregation of the recombinant fragment SHaPrP 90–232 of the hamster prion protein by Fourier transform infrared (FTIR) spectroscopy in H 2O and D 2O buffers. Difference spectra of this denaturation/aggregation reaction revealed a decrease of α-helical and turn structures and an increase of intermolecularly formed antiparallel β-sheet structure. Compared to previously examined critical oligomers in H 2O buffer, the temperature induced aggregates of SHaPrP 90–232 exhibited a less rigid but still strong hydrogen bonding pattern as indicated by the β-sheet specific difference band at 1624 cm −1. The denaturation/aggregation temperature of SHaPrP 90–232 was consistently determined using the β-sheet specific difference band observed in the H 2O or in the D 2O experiments. Further, the spectra obtained for the critical oligomers produced in appropriate buffer systems at 25 °C and at 37 °C revealed no significant differences in secondary structure.