The effect of denaturants on protein thermal stability analyzed through a theoretical model considering multiple binding sites.

BURGOS, M. INES; SERGIO A. DASSIE; GERARDO D. FIDELIO

BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2023 vol. 1871 p. 140920 - 140928

1570-9639

A novel mathematical development applied to protein ligand binding thermodynamicsis proposed, which allows the simulation, and therefore the analysis of the effects ofmultiple and independent binding sites to the Native and/or Unfolded proteinconformations, with different binding constant values. Protein stability is affected whenit binds to a small number of high affinity ligands or to a high number of low affinityligands. Differential scanning calorimetry (DSC) measures released or absorbedenergy of thermally induced structural transitions of biomolecules. This paper presentsthe general theoretical development for the analysis of thermograms of proteinsobtained for n-ligands bound to the native protein and m-ligands bound to theirunfolded form. In particular, the effect of ligands with low affinity and with a highnumber of binding sites (n and / or m> 50) is analyzed. If the interaction with the nativeform of the protein is the one that predominates, they are considered stabilizers and ifthe binding with the unfolded species predominates, it is expected a destabilizingeffect. The formalism presented here can be adapted to fitting routines in order tosimultaneously obtain the unfolding energy and ligand binding energy of theprotein. The effect of guanidinium chloride on bovine serum albumin thermal stability,was successfully analyzed with the model considering low number of middle affinitybinding sites to the native state and a high number of weak binding sites to theunfolded state.