At 12:01 PM -0500 7/7/09, Jacob Keller wrote:
does anybody know of a simple, fast way to determine whether a protein sample contains lipid, and roughly to determine the quantity? As corollary, does anybody know of a quick way to extract/remove the putative lipid? In my case, I am working with an extremely robust/stable soluble protein which may contain bacterial lipids.
Here is a reference describing an extremely robust/stable soluble protein (perhaps the same?) that when expressed as a recombinant protein in E. coli and purified will contain bacterial lipids. We used a chromatography resin that we called "Lipidex VI" to extract the lipids from this and related proteins without resorting to solvents that could denature the protein.
McDonnell P.A. et al., Journal of Medicinal Chemistry 2006 49 (16), 5013-5017.
Proteins treated with Lipidex in this way were fully competent for binding hydrophobic ligands in binding assays and in NMR and X-ray structural studies.
I believe that Lipidex VI can now be obtained from Sigma (#H6258), but they really jacked up the price in recent years. You need to treat all of your columns, tubing, and tubes with ethanol to remove trace lipids that could get sucked back into/onto your freshly de-lipidated protein. You may also need to do several de-lipidation cycles to get rid of most of the lipid, depending upon the strength with which your protein binds them.
Regards, - John --
