Abstract
We present a Molecular Dynamics simulation study of the effect of trehalose concentration on the structure and dynamics of individual proteins immersed in trehalose/water mixtures. Hen egg-white Lysozyme is used in this study and trehalose concentrations of 0%, 10%, 20%, 30% and 100% by weight are explored. Surprisingly, we have found that changes in trehalose concentration do not change the global structural characteristics of the protein as measured by standard quantities like the mean square deviation, radius of gyration, solvent accessible surface area, inertia tensor and asphericity. Only in the limit of pure trehalose these metrics change significantly. Specifically, we found that the protein is compressed by 2% when immersed in pure trehalose. At the amino acid level there is noticeable rearrangement of the surface residues due to the change in polarity of the surrounding environment with the addition of trehalose. From a dynamic perspective, our computation of the Incoherent Intermediate Scattering Function shows that the protein slows down with increasing trehalose concentration; however, this slowdown is not monotonic. Finally, we also report in-depth results for the hydration layer around the protein including its structure, hydrogen-bonding characteristics and dynamic behavior at different length scales.
Highlights
It has been established that trehalose is one of the most effective substances for increasing the stability of proteins [1,2,3,4,5,6,7]
The study we present in this paper contributes to this field by investigating the effect of trehalose concentration on the structure and dynamics of globular proteins
The first step in quantifying the effect of complex solvents on the structure of proteins involves the evaluation of the root mean-squared deviation (RMSD) of the protein atoms with respect to their positions in the crystal configuration
Summary
It has been established that trehalose is one of the most effective substances (biopreservants) for increasing the stability of proteins [1,2,3,4,5,6,7]. The presence of four hydroxyl groups on each ring allows for the formation of a large number of hydrogen bonds with the surrounding water [8] and protein surface. Water molecules usually form a spanning hydrogen-bonded network around the protein [9]. This network is destructured by the presence of trehalose [8]. The destructuring [8, 12] effect of trehalose leads to a decrease in the hydration water rendering the protein inactive. The presence of trehalose hinders the formation of ice, protecting the protein from liquid-water-to-ice transition induced damage
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