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Polyethylene glycol behaves like weak organic solvent.
MedLine Citation:
PMID:  21858782     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Effect of polyethylene glycol (PEG) on protein solubility has been primarily ascribed to its large hydrodynamic size and thereby molecular crowding effect. However, PEG also shows characteristics of organic solvents. Here, we have examined the solubility of glycine and aliphatic and aromatic amino acids in PEG solutions. PEG400, PEG4000 and PEG20000 decreased the solubility of glycine, though to a much smaller magnitude than the level achieved by typical organic solvents, including ethanol and dimethyl sulfoxide. PEG4000 showed varying degree of interactions with amino acid side chains. The free energy of aliphatic side chains marginally increased by the addition of PEG4000, indicating their weak unfavorable interactions. However, it significantly decreased the free energy of the aromatic side chains and hence stabilized them. Thus, it was concluded that PEG behaves like weak organic solvents; namely PEG destabilized (interacted unfavorably with) polar and charged groups and stabilized (interacted favorably with) aromatic groups. Interestingly, the interaction of PEG20000, but neither PEG400 nor PEG4000, with glycine resulted in phase separation under the saturated concentration of glycine. © 2011 Wiley Periodicals, Inc. Biopolymers, 2011.
Authors:
Atsushi Hirano; Kentaro Shiraki; Tsutomu Arakawa
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-8-19
Journal Detail:
Title:  Biopolymers     Volume:  -     ISSN:  0006-3525     ISO Abbreviation:  -     Publication Date:  2011 Aug 
Date Detail:
Created Date:  2011-8-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372525     Medline TA:  Biopolymers     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Wiley Periodicals, Inc.
Affiliation:
Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.
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