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molecular weight markers for SDS-PAGE

Curt Ashendel ashendel at aclcb.purdue.edu
Wed Dec 20 17:40:47 EST 1995

On 19 Dec 1995 16:04:20 GMT, 
Annette C. Hollmann  <ah690549 at bcm.tmc.edu > wrote:

>Are there any decent prestained molecular weight markers for SDS-PAGE
>available? Right now I am using markers from Sigma, and the bands are
>always 1/4 inch wide and very faint. My samples run ok, so the problem
>is definitely the markers and not the gel. I have to use prestained
>markers because I'm using the gels for Western blots. If I were staining
>the gels I'd just use a mix of purified proteins for a "homemade"
>set of markers. I need the size range of 20 to 90 kDa, which should


In addition to endorsing Amersham's rainbow markers as very good (but 
very expensive), here are two other suggestions: either (1) make you 
own prestained markers with your "homemade" set (easily and cheaply 
done using a reactive dye, and several different colors of reactive 
dyes are available from Sigma - look under "Reactive" in the 
catalog. Pool your set for one color or react separately with 
different colors for homemade rainbow. Just react protein with dy in 
phosphate buffer at 37 degrees or higher overnight and then dialyze 
until all unreacted dye is out), or (2) considering that dye-stained 
proteins do not run at their normal MW, consider staining your blot 
rather than using prestained markers. Sure, staining in methanol-based 
solvents shinks the blot a little, but there is not that much more 
error involved that when using prestained markers. We do this all the 
time. Even when staining the blot after blocking and probing the MW 
standards are relatively easily seen (certain tricks help, such as 
short stain times - 10 seconds, and loading at least 2 ug of each 
standard per lane).  BTW, our biggest use of prestained markers 
(homemade of course) is to mark a lane for cutting a blot to probe 
parts separately. The cut is always in the right place.

Curt Ashendel
Purdue University, West Lafayette, IN
ashendel at aclcb.purdue.edu

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