Question

What are the two main functions of SDS (sodium dodecyl sulfate) in an SDS-PAGE experiment? Explain each function.

Answer 1

SDS-PAGE experiment is used for the rough analysis of protein quantity and identification.

The two main functions of SDS(sodium dodecyl sulfate) in this process is to break down the di-sulphide bonds in multi chain proteins and give a negative charge to those linearized proteins.

In this process, the sample is prepared by boiling the SDS buffer sample for about 10-15 minutes. The sample buffer contains a reagent which colours the solution bright blue and can also contain mercaptoethanol. The mercaptoethanol is a chemical which breaks down the di-sulphide bonds in multi-chain proteins to release the separate fragments. So the primary function of SDS is to breakdown the complicated structure of sample proteins to leave them in thier primary structures.

After then, the SDS molecules can attach to these primary chains and give a uniform, negative charge to the linearized proteins.This allows the prepared proteins to be attracted towards the positive cathode and pass through the pores of the gel when an electric current is passed through it. This results in the identification of protein quantity.