Proteins in amorphous saccharide matrices: Structural and dynamical insights on bioprotection

Abstract

Abstract. Bioprotection by sugars, and in particular trehalose peculiarity, is a relevant topic due to the implications in several fields. The underlying mechanisms are not yet clearly elucidated, and remain the focus of current investigations. Here we revisit data obtained at our lab on binary sugar/water and ternary protein/sugar/water systems, in wide ranges of water content and temperature, in the light of the current literature. The data here discussed come from complementary techniques (Infrared Spectroscopy, Molecular Dynamics simulations, Small Angle X-ray Scattering and Calorimetry), which provided a consistent description of the bioprotection by sugars from the atomistic to the macroscopic level. We present a picture, which suggests that protein bioprotection can be explained in terms of a strong coupling of the biomolecule surface to the matrix via extended hydrogen-bond networks, whose properties are defined by all components of the systems, and are strongly dependent on water content. Furthermore, the data show how carbohydrates having similar hydrogen-bonding capabilities exhibit different efficiency in preserving biostructures.

Proteins in Saccharides Matrices and the Trehalose Peculiarity: Biochemical and Biophysical Properties

“…Trehalose systems lay between these two extremes. The presence of a major perturbation of the system in trehalose or maltose ternary matrices well agrees with the FTIR results, which show that in trehalose and maltose, but not in sucrose, protein addition sizably alters the WAB shape [148]. The model above presented depicts, for ternary systems, the presence of domains lacking in protein within a background where protein is more concentrated.…”

“…In this case, the proteins could try to make HB with other partners in the system; this could led to protein clusters, in which the protein are kept together via inter-protein HBs connections, trapped in structures distorted and with a dangerous aggregation potential following rehydration [101]. This different behavior of sucrose and trehalose formulations at very low water content is also in agreement with the observations that in sucrose systems the WAB is scarcely altered by the insertion of the protein, while it is significantly red shifted in ternary trehalose-protein-water compared to binary trehalose-water systems [148].…”

“…FTIR measurements were performed also in the homologue disaccharides sucrose and maltose, in raffinose, and in glucose matrices, at various hydration levels in the range 20-300 K; results were compared with those obtained in the trehalose matrices [54,148]. With the aim to rationalize the trehalose peculiarity with a model based on the characteristics of the HB network present in the system, ternary (protein-saccharide-water) system were also compared with corresponding binary systems (saccharide-water).…”

“…In what follows, we focus once again on the comparison among the three homologue disaccharides trehalose, sucrose, maltose (Fig. 1) [148].…”

Editorial on the Topical Issue “Neutron Biological Physics”

“…A molecular dynamics simulation study discusses macromolecular resilience as was defined from neutron spectroscopy experiments. The underlying mechanisms of bioprotection by sugars were explored by using data from Infrared Spectroscopy, Molecular Dynamics simulations, Small Angle X-ray Scattering and Calorimetry [11]. Time resolved small angle X-ray scattering in combination with other biophysical methods can contribute immensely to the study of protein dynamics and a paper presents a new set-up, including a microfluidic continuous-flow mixer, which provided results on unfolding dynamics.…”