Isothermal Microcalorimetry to Investigate Non Specific Interactions in Biophysical Chemistry

Abstract

Isothermal titration microcalorimetry (ITC) is mostly used to investigate the thermodynamics of “specific” host-guest interactions in biology as well as in supramolecular chemistry. The aim of this review is to demonstrate that ITC can also provide useful information about non-specific interactions, like electrostatic or hydrophobic interactions. More attention will be given in the use of ITC to investigate polyelectrolyte-polyelectrolyte (in particular DNA-polycation), polyelectrolyte-protein as well as protein-lipid interactions. We will emphasize that in most cases these “non specific” interactions, as their definition will indicate, are favoured or even driven by an increase in the entropy of the system. The origin of this entropy increase will be discussed for some particular systems. We will also show that in many cases entropy-enthalpy compensation phenomena occur.

Interactions of pectins with cellulose during its synthesis in the absence of calcium

“…All the de-binding data were fitted to the predicted kinetics of release for the limiting cases of pure diffusion control and surface resistance control. The results showed that the coefficient of internal diffusion and surface permeability both increased with increasing temperature, suggesting that the de-binding process involved an increase in entropy, as expected for non-specific interactions (Ball & Maechling, 2009). The data showed that pectin transfer from inside to outside of composites was dominated by the surface permeability, similar to the previous study of de-binding behaviour of arabinan/galactan (Lin et al, 2015).…”

Impact of molecular weight and degree of conjugation on the thermodynamics of DNA complexation and stability of polyethylenimine-graft-poly(ethylene glycol) copolymers

“…Supportive of this assignment is how this event was demonstrated to be entropy driven (Fig. 7a) as are most polyelectrolyte interactions, which are driven by the release of bound counterions and water upon complexation [54,[56][57][58][59][60]. The binding constant we determined for unconjugated PEI (7.6 × 10 8 M −1 ) is larger than that reported by Utsuno et al (1 × 10 6 M −1 ), but that study investigated a much smaller 600 Da branched PEI and linear, salmon testes DNA [46].…”

Physicochemical nature of interfaces controlling ferredoxin NADP+ reductase activity through its interprotein interactions with ferredoxin

“…3 and 4). ITC is one of the most powerful approaches for elucidating the physical, mechanical, and energetic natures of binding systems including molecular association mechanisms, binding modes, and driving forces for complexation [2,3,39].…”