What is the difference between acrylamide and bisacrylamide?

Acrylamide and Bisacrylamide, both are very important for proper polymerization. Acrylamide forms linear polymers whereas Bisacrylamide cross links these linear polymer. More numbers of cross links means smaller pore size. So, ratio of Acrylamide and Bisacrylamide determines pore size.

Hi Rasdin,

Prem is correct, you need both (points for you Prem). Just to help out a little more, we generally use a 30% Bis-Acrylamide solution for our standard SDS-PAGE. so 87.6g Acrylamide + 2.4g Bis-Acrylamide in 300mls final water. Just remember that acrylamide is a cumulative neurotoxin and is very dangerous to inhale the powder.

Cheers

Ron 

Here is an excellent article from National Diagnostics on this topic: https://nationaldiagnostics.com/electrophoresis/article/polyacrylamide-matrix

"For discussions of the composition of polyacrylamide gels, a standard nomenclature has been widely adopted. In this nomenclature, T represents the total percentage concentration (w/v) of monomer (acrylamide plus crosslinker) in the gel. The term C refers to the percentage of the total monomer represented by the crosslinker. For example, an 8%, 19:1 (acrylamide/bisacrylamide) gel would have a T value of 8% and a C value of 5%."

Rasdin, do you intend to analyze proteins or nucleic acids on your polyacrylamide gel?

Tq Prem for the answer and Ron for the explanation...really appreciated that.

Mark, i intend to analyzes p53 and bax protein...

I'm assuming that you will also be analyzing a loading control protein within the size range of your two proteins of interest. Bax should be about 20 kDa, am I correct? You can try  starting with a 12.5%, 37.5:1 (acrylamide/bisacrylamide) gel in that case to get good separation in that molecular weight range (20-50 kDa). I hope that helps.

Relevant paragraphs from the National Diagnostics article:

Control of the pore size of a polyacrylamide gel is accomplished by changing the T and C values. With increasing T, the pore size decreases in a nearly linear relationship. Higher percentage gels (higher T), with smaller pores, are used to separate smaller molecules. The relationship of C to pore size is more complex. Generally, the minimum pore size occurs when C is about 5% (a 19:1 gel). Decreasing C results in a more open pore structure because there are fewer crosslinker molecules. Increasing C beyond 5% also increases the pore size. This appears to be because of nonhomogeneous bundling of strands in the gel.

Researchers have settled on C values of 5.0% (19:1 acrylamide/bis) for most forms of denaturing DNA and RNA electrophoresis and 3.3% (29:1) for most native DNA and RNA gels. For SDS-PAGE electrophoresis of proteins, the standard C value that has been adopted is 2.6% (37.5:1)."

By the way, acrylamide is very toxic.

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