One reason can be found here:

http://www.bcp.fu-berlin.de/en/chemie/chemie/forschung/OrgChem/koksch/Research/aggregation/index.html

Well you could selectively precipitate the protein (a particular one) by gradually adding an organic solvent to water I guess.

Hi Sujessh,

This sort of method is already commonly used in drug design to test how hydrophobic or hydrophilic a prospective drug is. In these scenarios, you would test to see how a molecule partitions between an aqueous solution and an organic solvent, like 1-octanol, to get a measure of hydrophobicity. If you are interested you can read more about that here: https://en.wikipedia.org/wiki/Partition_coefficient

Anyway, what I'm thinking is that people might be using a similar sort of technique for proteins, to try and measure protein hydrophobicity by measuring their solubility in an organic solvent or perhaps they are trying to look at folding.

I hope this helps,

Mark

Protein aggregation is important for cell physiology: 

http://vladimirmatveev.ru/protoreaction.html

http://vladimirmatveev.ru/nativeaggregation.html

Protein aggregation in organic solvents allows us to understand the role of solvent polarity on protein-protein interactions.

Dear Sujeesh,

Thank you for your good and timely question. There can be various reason to use organic solvents while studying the protein aggregation. I am not sure whether you wish to know the purpose of use of alcohol in protein precipitation or use of organic solvents in the study related with protein aggregation that subsequently leads to amyloid formation. Whatever might be your intention, I will try to clarify your points based on my understanding.

The use ethanol or any other alcohol in protein solution leads to de[pletion of surface water and therefore it facilitate the precipitation of protein from bulk solution. This is a well established phenomenon and I am sure that you might be well aware of it.

Coming back to the second point, the principle behind using the organic solvents in protein aggregation is based on my personal research experience. For example, we use 1,1,1,1,1,1-Hexafluoroisopropanol (HFIP) to dissolve A beta peptide and then it is diluted with aqueous buffer to initiate aggregation. In HFIP the peptide remains in monomeric state and the peptide remains as alpha helical structure. The moment polarity of solution is changed from non-polar to polar it acquire beta-sheet structure and start inter-molecular aggregation. . Morover, even after dilution with aqueous buffer the presence of HFIP (> 10% V/V) significantly reduce rate of amyloid fibril formation and helps in stabilization of oligomeric state (Ref. http://www.ncbi.nlm.nih.gov/pubmed/22234970). Most of the time you will find that the use of organic solvents is mostly related with the basic studies dealing with structural transitions.

Please let me know if you have any further question.

Best wishes,

Jay

The strong interactive property of cosolvents itself invites scientists to investigate the introduction of various types of conformation alteration in proteins. The conformation alteration cause by cosolvents (Fluorinated and Non-fluorinated) includes : Molten globule state induction, unfolding, conformational stabilization, protein precipitation and aggregation as mentioned by you. All the effects are accordance with the concentration of cosolvents type of protein. Such properties of cosolvents depend on the polarity, relative dielectric constant etc. Since cosolvents are involved in the selective precipitation and purification of proteins, providing conformational induction, it is important to characterize the characteristic interaction  particular cosolvent with specific protein. The experiment performed by us indicated that even close value of  relative  dielectric constant show quite dissimilar effect for same protein.

My latest published paper can help you by giving detail answer asked by you

REGARDS............