The Protein Man's Blog | A Discussion of Protein Research

The aim of this blog is to highlight some of the routine problems that occur with Western blotting and suggest possible solutions.  The 7 common problems are:

Last week we reviewed some key factors to consider when coupling a label (biotin) to a protein.  The main factors considered were:

Biotin, a 244 Dalton vitamin (Vitamin H) molecule, exhibits an extraordinary binding affinity for avidin (Ka=10¹⁵M^-1) and streptavidin. Biotin and avidin interaction is rapid and once the bond is established it can survive up to 3M guanidine-hydrochloride and extremes of pH.

Question

How can I prevent my protein samples precipitating when loading on to a polyacrylamide gel (SDS-PAGE)?