Unusually viscous samples - Protein Sample Preparation (Jun/29/2009 )

Hi, All of a sudden my protein samples have become very viscous even after sonication. I add 2X loading buffer to the protein sample and the resulting protein sample is so viscous it gives me a very hard time when loading. I have been isolating and preparing the protein the same way and never had such viscous samples before, so this sudden problem is strange. Any help or ideas would be appreciated.

Have you tried DNase treatment?

I assume you got your protein from sonication of cells? The sample is usually viscous due to DNA as DNA is sticky. Try DNase treatment.