Coomassie Blue G-250 staining

[Paul N Hengen]

 In article <17015FC15S86.DCRCEP at mizzou1.missouri.edu>
 DCRCEP at mizzou1.missouri.edu (Elmer M. Price) writes:

>> THANKS FOR THE REFERENCE, BUT CAN ANYONE SIMPLY SAY WHAT THE DIFFERENCE
>> BETWEEN COOMASSIE G AND R IS?  ALSO, WHY IS THE METHANOL CONCENTRATION SO
>> CRITICAL?? PLEASE DON'T JUST SAY "BETTER FIXING".
> 
> I am not sure of the actual structural differences between G250 and R250
> (maybe in the Merck Index).  However, I am sure that R250 is the best stuff
> for staining SDS-PAGE gels, and I think that the G250 is used in protein
> quantitation assays (read "Bradford Assay").

CBB R-250 lacks two methyl groups on the phenyl rings (6 phenyl rings all
together). The structures are otherwise nearly identical. I found them in
the Fluka Catalog (pg. 381). CBB R-250 is said to be nearly 10 fold more
sensitive when used for staining proteins separated by SDS-PAGE. I have
used both and prefer CBB R-250.

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