Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) is a widely used laboratory technique in biochemistry and molecular biology for the separation and analysis of proteins. It is a type of polyacrylamide gel electrophoresis in which sodium dodecyl sulfate (SDS) is used to denature proteins, making them uniformly negatively charged, and imparts a linear relationship between the protein's molecular weight and its electrophoretic mobility.
The procedure involves the preparation of a polyacrylamide gel matrix with pores of varying sizes, which act as a molecular sieve, allowing the separation of proteins based on their molecular weight. The gel is poured into a glass plate sandwiched between two glass plates, allowing the creation of wells into which samples are loaded.
Before the gel electrophoresis, the protein samples are denatured and bound to SDS detergent molecules, enabling each protein to carry a negative charge proportional to its size. An electrical current is then applied to the gel, causing the proteins to migrate through the gel matrix based on their charge and size. The smaller proteins move faster and migrate further, while the larger proteins remain closer to the loading site.
Following electrophoresis, the proteins can be visualized by different staining methods, such as Coomassie Blue or silver staining. Additionally, the separated proteins can be transferred onto a membrane for immunoblotting to analyze specific proteins using antibodies.
SDS-PAGE is an invaluable tool for the separation, identification, and quantification of proteins in various biological samples. It allows researchers to study protein composition, purity, and molecular weight, facilitating the understanding of protein structure, function, and their roles in physiological processes.
