Thermal unfolding of calreticulin. Structural and thermodynamic characterization of the transition

HALLAK MARTA E.

BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018

1570-9639

alreticulin (CRT) is a calcium-binding protein that participates in several cellular processes including the control of protein folding and homeostasis of Ca2+. Its folding, stability and functions are strongly controlled bythe presence of Ca2+. The oligomerization state of CRT is also relevant for its functions. We studied the thermal transitions of monomers and oligomers of CRT by differential scanning calorimetry (DSC), circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR) in the presence and absence of Ca2+. We found three and two components for the calorimetric transition in the presence and absence of Ca2+ respectively. The presence of several components was also supported by CD and FTIR spectra acquired as a function of the temperature. The difference between the heat capacity of the native and the unfolded state strongly suggests that interactions between protein domains also contribute to the heat uptake in a calorimetry experiment. We found that once unf