Effect of PEG End-Group Hydrophobicity on Lysozyme Interactions in Solution Characterized by Light Scattering

We compare protein–protein and protein–polymer osmotic virial coefficients measured by static light scattering for aqueous solutions of lysozyme with low-molecular-weight, hydroxy-terminated (hPEG) and methyl-terminated (mPEG) poly(ethylene glycol) at two solution conditions: pH 7.0 and 0.01 M ionic...

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Bibliographic Details
Published in:Langmuir 2011-11, Vol.27 (22), p.13713-13718
Main Authors: Priya, M. Hamsa, Pratt, L. R, Paulaitis, M. E
Format: Article
Language:English
Subjects:
Animals
Biological Interfaces: Biocolloids, Biomolecular and Biomimetic Materials
Chemistry
Chickens
Exact sciences and technology
General and physical chemistry
Light
Muramidase - chemistry
Polyethylene Glycols - chemistry
Protein Binding
Scattering, Radiation
Solutions
Spectrophotometry, Ultraviolet
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Summary:We compare protein–protein and protein–polymer osmotic virial coefficients measured by static light scattering for aqueous solutions of lysozyme with low-molecular-weight, hydroxy-terminated (hPEG) and methyl-terminated (mPEG) poly(ethylene glycol) at two solution conditions: pH 7.0 and 0.01 M ionic strength, and pH 6.2 and 0.8 M ionic strength. We find that adding PEG to aqueous lysozyme solutions makes a net repulsive contribution to lysozyme–lysozyme interactions, independent of ionic strength and PEG end-group hydrophobicity. PEG end-group hydrophobicity has a profound effect on the magnitude of this contribution, however, at low ionic strength where mPEG-lysozyme attractive interactions become significant. The enhanced attractions promote mPEG–lysozyme preferential interactions at the expense of lysozyme self-interactions, which leads to lysozyme–lysozyme interactions that are more repulsive in the presence of mPEG. These preferential interactions also lead to the preferential exclusion of diffusable ions locally around the protein, which results in a pronounced ionic strength dependence of mPEG-mediated lysozyme–lysozyme interactions.
ISSN:0743-7463
1520-5827
DOI:10.1021/la203138k