Pressure- and temperature-induced unfolding and aggregation of recombinant human interferon-gamma: a Fourier transform infrared spectroscopy study

Abstract

The effect of hydrostatic pressure on the secondary structure of recombinant human interferon-gamma (rhIFN-gamma) and its biologically inactive truncated form rhIFN-Delta C15 has been studied using Fourier-transform IR (FTIR) spectroscopy. In situ observation of the pressure-induced changes using the diamond anvil cell shows that the alpha-helical structure is mainly transformed into disordered structure at high pressure. Increasing pressure also induces the formation of a gel. Addition of 0.5 M MgCl(2) significantly reduces the pressure stability. Releasing the pressure below 300 MPa results in the formation of intermolecular antiparallel beta-sheets, which is seldom observed. This suggests that the intermolecular beta-sheet of rhIFN-gamma is stabilized by electrostatic interactions that are disrupted at high pressure. For comparison we also studied the effect of temperature. Temperature-induced changes reflect extensive transformation of alpha-helical structure into intermolecular antiparallel beta-sheet, as is usually observed for most proteins.

Noncore Residues Influence the Kinetics of Functional TTR105–115-Based Amyloid Fibril Assembly

“…The similarity of X-ray diffraction patterns for fibrils formed from the TTR1 peptide, which lack reflections at ∼ 9.3 Å (2 × 4.7 Å) that can arise from antiparallel packing, indicates that TTR1-RGD and TTR1-RAD peptides may also be arranged parallel within the β-strand of the fibril core. 35,52,53 The Fourier transform infrared spectroscopy spectra for the three fibrils lack the maxima at ∼ 1684 cm − 1 40,42 observed for some fibrils with an antiparallel arrangement of β-strands, further supporting this arrangement, [54][55][56][57] although additional studies will be required to fully resolve the peptide structure within the fibril.…”

Fourier transform infrared spectroscopy provides an evidence of papain denaturation and aggregation during cold storage

“…Assignment of secondary structures for all the observed peaks was done according to previously published guidelines [24][25][26][27].…”

Some physico-chemical parameters that influence proteinase K resistance and the infectivity of PrP Sc after high pressure treatment

“…It seems that the structure of PrP Sc is stabilized in strong ionic buffers probably due to local effects on charged amino acids which result in stabilizing the electrostatic interactions. Indeed, it has been reported that intermolecular ß-sheets can be stabilized by electrostatic interactions (33). Furthermore, it is already known that ionic strength highly influences the solubility of proteins and also of PrP Sc in a way that prevents total inactivation through pressure.…”