Why is sds used in gel electrophoresis

Pour acrylamide solution for a separating gel. Overlay with water to prevent contact with air oxygen , which inhibits polymerization. Allow acrylamide to polymerize for minutes to form a gel. Remove the overlaid water. Proteins migrate at different rate depending on the concentration of the separating gel. Use an appropriate gel concentration for your target protein. Using a higher acrylamide concentration produces a gel with a smaller mesh size suitable for the separation of small proteins.

Gels with an acrylamide concentration gradient gradient gels are also used. Pour acrylamide solution for a stacking gel; insert a comb and allow the acrylamide to polymerize. Proteins are highly concentrated when they migrate through a stacking gel prior to entering a separating gel. The strength of the gel allows easy handling.

Polyacrylamide gel electrophoresis of SDS-treated proteins allows researchers to separate proteins based on their length in an easy, inexpensive, and relatively accurate manner.

By continuing to browse the site you are agreeing to our use of cookies. Due to these structural features detergents tend to aggregate into structures called micelles at high enough concentration; arranging themselves with their hydrophobic tails pointed inwards and their hydrophilic heads pointed outwards.

Detergents come in three types: ionic cationic and anionic and non-ionic. Ionic detergents such as anionic SDS are used for gel electrophoresis as they are highly useful for protein solubilization, linearization and for establishing a uniform charge in preparation for gel electrophoresis. Proteins consist of stretches of hydrophilic and hydrophobic amino acids which generally fold in such a way that hydrophobic amino acids are buried in the interior of the protein and hydrophilic amino acids are on the exterior of the protein.

This tendency of proteins allows for cytoplasmic proteins to dissolve into the aqueous environment of the cell, but membrane proteins which typically have exposed hydrophobic sites that allow them to bind to or integrate into the lipid bilayer of the cell, are not typically readily soluble.

The hydrophobic tail of a detergent stabilizes any hydrophobic amino acids present in the protein and the hydrophilic head disrupts any non-covalent bonds between amino acids to unfold the protein. Macromolecules will be differentiated according to their electrophoresis mobility, which is a function of the length, conformation, and charge of the molecule. In general, macromolecules may be run in their native state or in denatured forms. To separate molecules based on their lengths, samples are run in denaturing conditions.

The binding of SDS to the polypeptide chain imparts an even distribution of charge per unit mass.