The principle and method of SDS-polyacrylamide gel electrophoresis (SDS-PAGE)

The principle

SDS-PAGE is an analytical technique to separate proteins based on their molecular weight.

When proteins are separated by electrophoresis through a gel matrix, smaller proteins migrate faster due to less resistance from the gel matrix. Other influences on the rate of migration through the gel matrix include the structure and charge of the proteins. In SDS-PAGE, the use of sodium dodecyl sulfate (SDS, also known as sodium lauryl sulfate) and polyacrylamide gel largely eliminates the influence of the structure and charge, and proteins are separated solely based on polypeptide chain length. SDS is a detergent with a strong protein-denaturing effect and binds to the protein backbone at a constant molar ratio. In the presence of SDS and a reducing agent that cleaves disulfide bonds critical for proper folding, proteins unfold into linear chains with negative charge proportional to the polypeptide chain length.

principle

Polymerized acrylamide (polyacrylamide) forms a mesh-like matrix suitable for the separation of proteins of typical size. 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.

principle

Procedure

Preparation of polyacrylamide gel

※ An example performed at MBL

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Preparation of samples

※ An example performed at MBL

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Electrophoresis

※ An example performed at MBL

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Related Links

*Antibody

→Antibody basics

→Antibodies as a research tool

*Qualitative and quantitative measurements of proteins using antibodies

*Fractionation and purification of proteins