Trehalose Effect on Low Temperature Protein Dynamics: Fluctuation and Relaxation Phenomena

Abstract

We performed spectral diffusion experiments in trehalose-enriched glycerol/buffer-glass on horseradish peroxidase where the heme was replaced by metal-free mesoporphyrin IX, and compared them with the respective behavior in a pure glycerol/buffer-glass (Schlichter et al., J. Chem. Phys. 2000, 112:3045-3050). Trehalose has a significant influence: spectral diffusion broadening speeds up compared to the trehalose-free glass. This speeding up is attributed to a shortening of the correlation time of the frequency fluctuations most probably by preventing water molecules from leaving the protein interior. Superimposed to the frequency fluctuation dynamics is a relaxation dynamics that manifests itself as an aging process in the spectral diffusion broadening. Although the trehalose environment speeds up the fluctuations, it does not have any influence on the relaxation. Both relaxation and fluctuations are governed by power laws in time. The respective exponents do not seem to change with the protein environment. From the spectral dynamics, the mean square displacement in conformation space can be determined. It is governed by anomalous diffusion. The associated frequency correlation time is incredibly long, demonstrating that proteins at low temperatures are truly nonergodic systems.

Moving boundary problems governed by anomalous diffusion

“…Eaves & Reichman (2008) explored subdiffusive exit-time behaviour within biomolecular enzyme kinetics. Additional biological studies include that of anomalous electrodiffusion by Langlands et al (2009), anomalous *Author for correspondence (chris.j.vogl@gmail.com). diffusion of morphogens by Yuste et al (2010) and anomalous diffusion of proteins through trehalose-water solutions by Schlichter et al (2001). In addition to proteins, Conrad & de Pablo (1998) find that water molecules follow anomalous diffusion in trehalose-water solutions, albeit only for short periods of time.…”

The Effect of Methanol on Lipid Bilayers: An Atomistic Investigation

“…To investigate the characteristics of the membranes and to obtain the intriguing physicochemical aspects of membranes systems many experiments have been performed. 13,16,[24][25][26]35,38 Although experimental approach is still the corner stone of membrane research, it is often difficult or even impossible to obtain a thorough understanding of the phenomena taking place in lipid bilayers by experiments only. Recent development of new algorithms 23 and revolutionary advances in the computational power available to scientists has permitted computer simulations of biological membranes to advance at a comparable pace with that of experiments.…”

Structural fluctuations and aging processes in deeply frozen proteins

“…To learn something about this interesting question, we dissolved HRP in a trehalose-enriched water/glycerol solution [7]. (In addition, as will be presented in the next chapter, the behavior of cytochrome c in a dry trehalose-film was investigated.)…”

“…We compared the spectral diffusion behavior of a sample, where the proteins were dissolved in a water-glycerol mixture with the respective one in a trehalose-water-glycerol solution. (For experimental details, see [7].) Shown are masterplots, i.e., the data have already been scaled with their aging time dependence as explained above.…”

“…To do so, one needs to know how structural rearrangements are connected with the frequency fluctuations of the chromophore. This can be achieved by a simple model [7]: we consider a chromophore inside a protein, which is separated from the various aminoacid-residues by distances R i . The interaction with them gives rise to a frequency shift, which is simply the sum over the contributions of all residues:…”