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

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)?

Question

I am looking for a stain to use on a Tris-Tricine polyacrylamide gel that will stain a small peptide (~3kDa) that has no positively-charged amino acids. It's a very acidic peptide consisting only of neutral and negatively-charged amino acids. Coomassie does not work. Thank you.