SDS-PAGE Staining - (Jan/28/2006 )

Can the stain b added to the sample (protein)
before loading it to the (PAGE)gel??

What is the molecular weight of coommassie blue-250

Plz help to get rid of staining stuff
someday it stains excess or else it goes off before
documenting

thanks

What I do is to stain after electrophoresis, never heard about putting coomasie blue to the sample before loading but i imagine that it could interfere with migration
I use 30 ml methanol, 10 ml coomasie ble, 10 ml water and live the gel ON slowly agitating. next day i put the gel on a plastic bag after drying it a bit

CAn silver staining be done

silver staining can be done, its a far mor sensitive stain so you will pick up a lot more bands. It is however more laborious, and you have to make the solutions fresh. Generally you load about 100 times less protein than you would for a coomassie stained gel. You can destain gels if you overstain. I use solution containing 30 % methanol and 10 % acetic acid. Its quite potent and will destain your gel quite quickly (over an hour) so keep an eye on it. You will need to change the solution as it destains.

if the gel comes white (too dried, this is reversible.

This is probably too late for you as your post is old, but you cannot prestain your proteins passively with Coomassie Blue and then run them in SDSPAGE.
This is because the stain binds by charge and the SDS will interfere.
You would need to covalently attach a dye to the protein (like companies do for prestained markers).
I can only imagine that this method will be far more tedious and will affect your mobiliities compared with just staining with Coomassie or silver after the run.