molecular weight markers - to use prestained or not (Mar/07/2005 )

I was told to use unstained molecular weight markers for my western blot instead of prestained ones. Reason- the prestained ones do not resolved accurately in the gel. Any other reasons or feedback would be much appreciated.

hi
i've never use the prestained and the unprestained markers on the same gel, but my experiments did not reveal a significative difference.

Fred

I've used two different prestained MW on the same gel (one from Sigma and the other from Bio-Rad), and they didn't make complete sense: the 90 kD band on one of them was above the 110 kD band on the other, and things like that. Quite a bit of difference. I must say that I didn't have the specific information sheet for that batch of Bio-Rad markers, only the general information on the catalog, and the MW can change a bit from batch to batch depending on how the dye-coupling reaction goes, but this was >20 kD difference. Anyway, I'm still using pre-stained weights, for convenience. It is not much of a problem is you're doing a western and you get only a band on the approximate size range, but if you want to do something more specific, maybe is better you use unstained markers.
Cheers!

Hi
there is actually a marker special for western blots, it from invitrogen and called the magic marker. it works fine for me , try it , it might work for you
cheers