The field of biochemistry, molecular biology, and biotechnology often employs Polyacrylamide gel electrophoresis (PAGE) as a tool for separating biological molecules. This method separates molecules like proteins and nucleic acids based on factors such as shape, size, mass, and charge.
The polymer polyacrylamide forms soft gels when interlinked, providing consistent pore size and higher resolving power than agarose. Two gel techniques utilize this polymer: Sodium-dodecyl sulfate (SDS) PAGE and Native PAGE, which use denature and non-denatured gels, respectively, for separation.
An Overview of SDS PAGE
Sodium-dodecyl sulfate polyacrylamide gel electrophoresis, or SDS PAGE, separates protein molecules ranging from 5 to 250 kDa. The basis for this separation is the molecular weight of the proteins.
The anionic surfactant, sodium dodecyl sulfate, is added during gel preparation to mask the proteins' intrinsic charges and standardize their charge to mass ratio. Essentially, this process denatures the
proteins
and assigns them a negative charge.
Exploring Native PAGE
Native PAGE, on the other hand, uses non-denatured gels to separate proteins. Unlike SDS PAGE, no denaturing agent is added during gel preparation. This allows proteins to separate based on their charge and size.
The separation in Native PAGE relies on the proteins' conformation, folding, and
amino acid
chains. The proteins remain undamaged in this process and can be extracted after separation.
Comparing SDS PAGE and Native PAGE
SDS PAGE
Native PAGE
Brief Overview
SDS PAGE separates proteins based on their mass.
Native PAGE separates proteins based on their size and charge.
Gel State
The gel is denatured in SDS PAGE.
The gel remains non-denatured in Native PAGE.
Denaturation Process
SDS is added to give the protein samples a negative charge.
No denaturing agent is used.
Separation Criteria
Proteins in SDS PAGE are separated based on their mass.
Proteins in Native PAGE are separated based on their size and charge.
Protein Stability and Retrieval
Proteins in SDS PAGE are unstable and cannot be retrieved post-separation.
Proteins in Native PAGE remain stable and can be retrieved after separation.