SDSpolyacrylamide

SDSpolyacrylamide refers to the polyacrylamide gel matrix used in SDS-PAGE, a common laboratory method for separating proteins by molecular weight. The gel is formed from polyacrylamide chains that are crosslinked with a bifunctional crosslinker, typically N,N'-methylenebisacrylamide. Gel formation is initiated by ammonium persulfate and catalyzed by TEMED, producing two regions: a stacking gel with a low acrylamide concentration and a resolving gel with a higher concentration that determines resolving power.

The polymer network provides a porous matrix through which proteins migrate under an electric field. In SDS-PAGE, proteins are denatured and coated with SDS, which imparts a relatively uniform negative charge-to-mass ratio. As a result, protein separation depends primarily on size rather than charge or shape. Smaller proteins traverse the gel pores more quickly than larger ones, producing a separation profile that can be compared to molecular weight standards.

Gels are available in various acrylamide percentages and can be cast as homogeneous or gradient matrices to optimize resolution for specific size ranges. A stacking gel concentrates samples before entry into the resolving gel, improving lane consistency and resolution. Electrophoresis is typically followed by staining or blotting to visualize or transfer separated proteins for further analysis.

Applications include estimating protein molecular weights, assessing purity, and preparing samples for Western blotting or mass spectrometry. While SDS-PAGE with SDSpolyacrylamide offers high resolving power, handling acrylamide requires safety precautions due to its neurotoxicity, and gel selection should match the expected protein size range for effective separation.