Hi Emile,

I cast 15% SDS gels when working with 13KDa and 15KDa proteins. Just going by size I will advise you to go for 8% and 10% gels in the beginning to screen for optimum results. Use acrylamide/bisacrylamide mixtures for casting gels for PAGE.

You mean a SDS-PAGE, right? I would suggest 12%-15% gels for a first try. It also depends on your overall system, though. Performance is different, when using different buffers, temperatures, voltages,...

You should always use Acryl/bisacrylamid-mixtures for PAGE. The gel forms by polymerization. If you only add acrylamide you end up with linear molecules. The bisacrylamide is necessary for cross linking these linear molecules. Without bis your gels won't be stable, if they form at all. Ratio of both monomers is very important for your gel performance. (You may also read this related topic: https://www.researchgate.net/post/What_is_the_difference_between_acrylamide_and_bisacrylamide)

Hi Emile,

I cast 15% SDS gels when working with 13KDa and 15KDa proteins. Just going by size I will advise you to go for 8% and 10% gels in the beginning to screen for optimum results. Use acrylamide/bisacrylamide mixtures for casting gels for PAGE.

I use these gels: http://www.bio-rad.com/en-be/sku/3450125-4-12-criterion-xt-bis-tris-protein-gel-26-well-15-ul

(4-12% Bis Tris) with very nice results for proteins ranging from 10 to 300 kDa.

Hi there,

10% gel  in Tris-Glycine will do (see the following :

http://images.google.fr/imgres?imgurl=http://www.aesociety.org/areas/images/1d-fig6.jpg&imgrefurl=http://www.aesociety.org/areas/one_de.php&h=409&w=677&tbnid=UmyQ67DadVMGDM:&tbnh=90&tbnw=149&docid=U5d3x-fi3PEeQM&usg=__G-qMx2KeZ2zbK6dKQuIPQ88fmos=&sa=X&sqi=2&ved=0ahUKEwjzpsrd28PPAhXEXRQKHSGhAmsQ9QEILTAB).

About the second question : if your are using pure acrylamide solution for your gels it also means you are using pure bis-acrylamide solution. In the 37.5/1 solution, the mix of the 2 is already done so both stocks are different. You might adapt a recipe but you can't strictly replace one by the other without affecting the global composition of your gel. For more info about the different stocks and the use you may make of them:

http://www.bio-rad.com/webroot/web/pdf/lsr/literature/LIT492.pdf

Dear Alghoul, 

Considering the molecular weight of most ladders or markers which is up to 240-250kDa, so the molecular weight of your sample is relatively low. The higher the percent of acrylamide, the smaller pores you will find. This causes the gel more appropriate for the mobility and separation of lower molecular weight protein samples. In my idea gels with 12-15% separating gel and 4-4.5% % stacking  gel would be appropriate for your sample.

Good Luck

Yes 4% for stacking gel and 10% for resolving gel. For your second question Dominique is right I agree with him.

We use 12% gels for 25-80 Kda proteins. The stock ratio of acrylamide: bisacrylamide is 29.2:0.8