Unfolding and aggregation of lysozyme: A thermodynamic and kinetic study by FTIR spectroscopy

Paola Sassi (1) , Alessandra Giugliarelli (1) , Marco Paolantoni (1) , Assunta Morresi (1) , Giuseppe Onori (2)

1 Dipartimento di Chimica
2 UNIPG - Università degli Studi di Perugia = University of Perugia

The unfolding of hen egg-white lysozyme dissolved both in DO and CHCHOD/DO was studied by Fourier Transform Infrared (FTIR) absorption spectroscopy at different protein concentrations. A detailed description of the local and global rearrangement of the secondary structure upon a temperature increase, in the range 295 to 365K, was obtained through the analysis of the amide I band. Thermodynamic parameters for the melting, and the effect of the co-solvent in determining a change in thermal stability of the protein were evaluated. The protein-protein interactions were also followed as a function of temperature: a strong dependence of the cluster stability and aggregation yield on the solvent composition was observed. Finally, FTIR spectra taken at successive time steps of the aggregation enabled intermolecular contacts to be monitored as a function of time, and kinetic information to be obtained showing that both unfolded and folded states of lysozyme act as reactants for the clustering event.

Mots clés: lysozyme; unfolding; aggregation; FTIR; kinetics

Domaines: Chimie-Physique [physics.chem-ph]

Paola Sassi, Alessandra Giugliarelli, Marco Paolantoni, Assunta Morresi, Giuseppe Onori. Unfolding and aggregation of lysozyme: A thermodynamic and kinetic study by FTIR spectroscopy. Biophysical Chemistry, 2011, 158 (1), pp.46. ⟨10.1016/j.bpc.2011.05.002⟩. ⟨hal-00770491⟩