RIPA Buffer precipitation trouble - (Mar/05/2010 )

I am using the following composition of RIPA buffer: 1X RIPA (1% DOC Na+, 1% TritonX-100, 0.1% SDS, 1M Tris-Cl, pH 7.4). The buffer is precipitating few days after I add the protease inhibitors?

Does any one have an idea what could cause this?

Thanks

A0110 on Mar 5 2010, 09:28 PM said:

I am using the Protease Inhibitor Cocktail "Complete". I tried today to add only iodacetamide to RIPA buffer stock and will be adding the protease inhibitor tablets just before use.

Are you using the EDTA+ or -free complete? (just a random guess, the EDTA may be precipitating out?)

be aware that protease inhibitors only function for a few days after being put into solution (and only last approx 6 months frozen in solution).

I was using EDTA free RIPA. But I knew what was causing my problem. I used 1M Tris buffer to make up 1X RIPA. I should have used a final concentration of 0.1 Tris HCl. So, that should have been precipitating my buffer once I add anything to it.

Thank you guys.