Stability of globular proteins in H₂O and D₂O

Abstract

In several experimental techniques D2O rather then H2O is often used as a solvent for proteins. Concerning the influence of the solvent on the stability of the proteins, contradicting results have been reported in literature. In this paper the influence of H2O-D2O solvent substitution on the stability of globular protein structure is determined in a systematic way. The differential scanning calorimetry technique is applied to allow for a thermodynamic analysis of two types of globular proteins: hen's egg lysozyme (LSZ) with relatively strong internal cohesion ("hard" globular protein) and bovine serum albumin (BSA), which is known for its conformational adaptability ("soft" globular protein). Both proteins tend to be more stable in D2O compared to H2O. We explain the increase of protein stability in D2O by the observation that D2O is a poorer solvent for nonpolar amino acids than H2O, implying that the hydrophobic effect is larger in D2O. In case of BSA the transitions between different isomeric forms, at low pH values the Nm and F forms, and at higher pH values Nm and B, were observed by the presence of a supplementary peak in the DSC thermogram. It appears that the pH-range for which the Nm form is the preferred one is wider in D2O than in H2O.

The effect of deuterium oxide on the stability of the collagen model peptides H‐(Pro‐Pro‐Gly)10‐OH, H‐(Gly‐Pro‐4(R)Hyp)9‐OH, and Type I collagen

“…39 This exchange strengthens the hydrogen bond and this could be partially responsible for the increase in the observed stability. Gough and Bhatnagar 33 reported the transition enthalpy of (Pro-Pro-Gly) 10 32 In contrast, Makhatadze et al 38 claimed that the transition enthalpy of RNase and lysozyme decrease from H 2 O to D 2 O. They claimed that almost all the changes in the enthalpy of unfolding due to water isotopic substitution can be rationalized by changes in hydration of the buried nonpolar groups.…”

Structural Analysis of Kinetic Folding Intermediates for a TIM Barrel Protein, Indole-3-glycerol Phosphate Synthase, by Hydrogen Exchange Mass Spectrometry and Gō Model Simulation

“…The stabilization of sIGPS in 2 H 2 O could result in the appearance of a small fraction of the native state and uniform protection of all peptides at 5 M urea. 30,31 Thus, the product of the burst-phase folding reaction is an off-pathway misfolded form that represents a thermodynamic state distinct from the unfolded state (Scheme 2). However, the burst-phase intermediate is not the on-pathway equilibrium intermediate, I a , as previously concluded.…”

X-ray structure of perdeuterated diisopropyl fluorophosphatase (DFPase): perdeuteration of proteins for neutron diffraction

“…This is coupled with a slightly longer distance between the heavy atoms of the donor-acceptor pair. The resolution of the structure is not sufficient to ascertain these differences and can be further analyzed using higher resolution data (Efimova et al, 2007).…”