Protein Solubility - How to determine? (Apr/01/2007 )

I have a question during one of my presentations.
She asked me whether my protein is soluble or not?

I don't really get the question. My understanding is that when I lyse the cells and release it out. I solubilise with strong denaturants such as urea or imidazole.

Is she asking me whether in the cells itself, the protein is in soluble form or insoluble form?

If so, how can I determine such feature?

Thanks alot, guys...

-timjim-

QUOTE (timjim @ Apr 2 2007, 04:14 PM)

I think that is the question that was meant. The fact that you have solubilised with urea etc suggests the protein isn't soluble. I presume you have done the expt of collecting some cells, lysing, pelleting the debris and running an SDS-PAGE. If the bulk of the protein is in the insoluble fraction, it's insoluble, if it's in the S/N, it is soluble.

-swanny-

Oh..then I get it. Since it present in supernatant after lysed with urea, the protein should be in insoluble form. Thanks for clarifying.

-timjim-