We have the reagents, instruments and accessories you need to carry out SDS-PAGE electrophoresis of your protein samples. These include:

What is SDS-PAGE electrophoresis?

Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is a technique for separating proteins based on their ability to move within an electrical current, which is a function of the length of their polypeptide chains or of their molecular weight. This is achieved by adding SDS detergent to remove secondary and tertiary protein structures and to maintain the proteins as polypeptide chains. The SDS coats the proteins, mostly proportional to their molecular weight, and confers the same negative electrical charge across all proteins in the sample. Glycosylated proteins may not migrate at their expected molecular weight since their migration is based more on the mass of their polypeptide chains, not the sugars that are attached (Sambrook, etal, 1989). 

The most widely used gel system for separating a broad range of proteins by SDS-PAGE is the Laemmli system (1970) which uses tris-glycine gels comprised of a stacking gel component (which is used to help focus the proteins into sharp bands at the beginning of the electrophoretic run) and the resolving gel where varying acrylamide gel percentages are used to separate the proteins based on their mass weight.  This classic system uses a discontinuous buffer system where the pH and ionic strength of the buffer used for running the gel (Tris pH 8.3) is different from the buffers used in the stacking gel (Tris, pH 6.8) and resolving gel (Tris, pH 8.8).

The highly alkaline operating pH of the Laemmli system may cause band distortion, loss of resolution, or artifact bands. The major causes of poor band resolution with the Laemmli system are:

  • Hydrolysis of polyacrylamide at the high gel casting pH, resulting in a short shelf life of 4–6 weeks
  • Chemical modifications such as deamination and alkylation of proteins due to the high pH of the separating gel
  • Reoxidation of reduced disulfides from cysteine containing proteins as the redox state of the gel is not constant
  • Cleavage of Asp-Pro bond of the proteins when heated at 100°C in the Laemmli sample buffer, pH 5.2


The NuPAGE® SDS PAGE Gel System is a revolutionary neutral pH, precast, discontinuous SDS-PAGE mini-gel system providing maximum stability of both proteins and gel matrix during electrophoresis, and better band resolution than other gel systems.  Advantages of this system include:

  • Superior protein band resolution and stability
  • Faster sample run times—35–50 minutes
  • Longer product shelf life—1 year
  • More efficient western blot transfer

Learn more about the NuPAGE® SDS PAGE Gel System

Read about the exceptional performance of NuPAGE® SDS-PAGE Gel System.

Download the application note—Novex® NuPAGE® Bis-Tris Electrophoresis System: Performance comparison with the Bio-Rad® Mini-PROTEAN® TGX™ System.

View the citation—Models of Protein Modification in Tris-glycine and Neutral pH Bis-Tris Gels During Electrophoresis: Effect of Gel pH

SDS-PAGE workflow



Protein blotting
Protein detection

Affinity protein isolation

Convenient protein separation

Efficient, 7-minute western blotting

Accurate protein identification


  1. Laemmli, UK (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227:680.
  2. Sambrook, J, Fritsch, EF, Maniatis, T (1989) Molecular Cloning: A Laboratory Manual, 2nd Edition. Cold Spring Harbor Press NY pp18.47-18.59.

For Research Use Only.  Not intended for any animal or human therapeutic or diagnostic use.