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Arch Biochem Biophys. 2015 Mar 15;570:66-74. doi: 10.1016/j.abb.2015.02.021. Epub 2015 Feb 21.

Effects of osmolytes on protein-solvent interactions in crowded environment: Analyzing the effect of TMAO on proteins in crowded solutions.

Author information

1
Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA; Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
2
Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA; Department of Morphology and Animal Physiology, Federal Rural University of Pernambuco, 52171-900 Recife, PE, Brazil.
3
Analiza, Inc., 3516 Superior Ave., Suite 4407B, Cleveland, USA.
4
Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia.
5
Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA.
6
Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA; Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia; Department of Biological Science, Faculty of Science, King Abdulaziz University, PO Box 80203, Jeddah 21589, Saudi Arabia; Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia. Electronic address: vuversky@health.usf.edu.

Abstract

We analyzed the effect of a natural osmolyte, trimethylamine N-oxide (TMAO), on structural properties and conformational stabilities of several proteins under macromolecular crowding conditions by a set of biophysical techniques. We also used the solvent interaction analysis method to look at the peculiarities of the TMAO-protein interactions under crowded conditions. To this end, we analyzed the partitioning of these proteins in TMAO-free and TMAO-containing aqueous two-phase systems (ATPSs). These ATPSs had the same polymer composition of 6.0 wt.% PEG-8000 and 12.0 wt.% dextran-75, and same ionic composition of 0.01 M K/NaPB, pH 7.4. These analyses revealed that there is no direct interaction of TMAO with proteins, suggesting that the TMAO effects on the protein structure in crowded solutions occur via the effects of this osmolyte on solvent properties of aqueous media. The effects of TMAO on protein structure in the presence of polymers were rather complex and protein-specific. Curiously, our study revealed that in highly concentrated polymer solutions, TMAO does not always act to promote further protein folding.

KEYWORDS:

Aqueous two-phase system; Macromolecular crowding; Partitioning; Protein stability; Protein structure; Solvent interaction analysis; Structural changes

PMID:
25712220
DOI:
10.1016/j.abb.2015.02.021
[Indexed for MEDLINE]

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