Coomassie: brilliant blue G or R? - (Oct/15/2007 )
Hi, I have been looking through prior posts to no avail... I am going to do a coomassie staining for the first time, and don't know whether to order brilliant blue G (which contains methanol) or brilliant blue R (which contains ethanol). I do know that the staining and destaining solutions are to contain methanol.
G for Bradford, R for CBB
The protocol I have has neither "Bradford" nor "CBB" (which I'm guessing means "coomassie brilliant blue?") written anywhere in it. As I previously stated, I'm doing this for the first time ever. I don't even know the difference between "Bradford" and "CBB."
I should have been more specific. The protocol I am to use calls for:
10x SDS running buffer
for 1 liter….
30.2 g Tris
144 g Glycine
10 g SDS
pH to 8.3; bring volume up to 1L with dH20; store at room temperature.
dilute to 1x with dH20
0.500 g Brilliant Blue
500 mL methanol
100 mL glacial acetic acid
400 mL dH20
Mix well; store at room temperature; can be reused 2-3 times
*BenchMark™ Pre-stained Protein Ladder 10748-010 Invitrogen
*Criterion Tris-HCl Gel (4-20% gradient) 345-0033 BioRad
*Laemmli sample buffer, 30 ml 161-0737 BioRad
brilliant blue g is coomassie brilliant blue g-250.
brilliant blue r is coomassie brilliant blue r-250.
g-250 is more specific in its binding properties and, hence, less sensitive than r-250.
g-250 is a greenish-blue when used for staining. it is brown and turns blue (absorbance wavelength shift) when used for the bradford protein assay.
r-250 is dark blue (with a little reddish component) when used to stain. it is not used for the bradford assay.
g-250 is also the dye of choice for modified coomassie brilliant blue staining methods (eg: colloidal, blue silver).
there are, obviously, some chemical differences between them (you can look it up if you are interested, i did, some years ago, but i don't remember anything).
we routinely use r-250 at 5x the strength of your formula (0.25%) but yours is fine.
thankx alot its really new information for me.