Why SDS-PAGE Can Be Used for Protein Purification
SDS-PAGE electrophoresis is a commonly used technique for protein separation and purification. Its principle relies on the properties of SDS (sodium dodecyl sulfate) and polyacrylamide gel to separate protein samples into different-sized bands, thus achieving protein purification.
1. Role of SDS
SDS is a surfactant that interacts with hydrogen bonds and hydrophobic interactions within protein molecules, unfolding them into linear structures. SDS also imparts a negative charge to proteins, causing them to move towards the anode in an electric field. In this way, SDS enables the separation of proteins by molecular weight during gel electrophoresis.
2. Role of Polyacrylamide Gel
Polyacrylamide is a polymer that forms a gel with a mesh-like structure. This gel has a certain porosity, allowing protein molecules to pass through in the electric field. The pore size of polyacrylamide gel can be adjusted by varying its concentration and crosslinking, thus facilitating protein separation.
3. Separation Process
In SDS-PAGE, the protein sample is first mixed with SDS, unfolding the proteins into linear structures and imparting a negative charge. The mixture is then loaded onto the polyacrylamide gel, and an electric field is applied, causing proteins to migrate towards the anode. Proteins with different molecular weights move at different speeds through the gel. Smaller proteins move faster, while larger ones move more slowly. Ultimately, the protein sample forms a series of bands on the gel, each representing a protein of a specific molecular weight.
4. Purification Process
In SDS-PAGE, target protein bands on the gel can be cut out for purification. After cutting the target protein bands, further processing steps like elution, concentration, and re-dissolution can be carried out to obtain the purified protein sample.
MtoZ Biolabs, an integrated chromatography and mass spectrometry (MS) services provider.
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