SDS-PAGE

SDS-PAGE Electrophoresis of Proteins

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

SDS-PAGE Buffers — gel casting, running buffers, sample buffers, transfer buffers
Gel Casting Reagents & Accessories — polyacrylamide, TEMED, gel cassettes and combs
Precast SDS-PAGE Protein Gels — a wide selection of formulations and formats
Electrophoresis Instruments — power supplies, electrophoresis chamber systems
Protein Ladders and Standards — for multiple platforms and different protein molecular weights
Protein Gel Stains — for all imaging platform and detection system
Protein Gel Transfer Systems — for Western blot analysis and protein detection

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

NuPAGE® SDS PAGE Gel System

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.

SDS-PAGE Workflow

Sample Preparation		SDS-PAGE Gel Electrophoresis		Protein Blotting		Protein Detection

Affinity Protein Isolation	Convenient Protein Separation	7-Minute Efficient Western Blotting	Accurate Protein Identification

Dynabeads® Nickel-Chelating Resin Proteases Antibodies	Precast Gels Ready-to-Dilute Buffers Protein Standards Power Supplies	iBlot™ Transfer Device Pre-cut Blotting Membranes	Total-Protein Stains Multiplexable Stains Sensitive Immunodetection System