Ethylene glycol-mediated reduction

Since solubility in water is generally mediated by the polar groups on the protein surface, it follows that any reduction in solvent polarity might tend to reduce protein solubility. This is generally the case. Addition of non-polar solutes such as ethanol, methanol or polymers such as poly(ethylene glycol) ( PEG ) usually lowers the protein solubility (Figure 5.18). 

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