![]() ![]() After electrophoresis, the PAGE gel is incubated in zymogram renaturing buffer. Proteins are separated on the gels under denaturing, nonreducing conditions. Zymogram PAGE gels detect proteins that have proteases that can use gelatin or casein as a substrate. Additionally, for samples that have been electrophoresed in immobilized pH gradient (IPG) strips for 2-D electrophoresis, mini and midi precast gels are available with wells that accommodate the strips for the second-dimension electrophoresis. Precast gels are available with both broad and narrow pH gradients. An IEF PAGE gel can be used to separate native proteins or proteins with charged post-translational modifications (such as phosphorylation). In a pH gradient, proteins migrate until they have no net charge - when the pH equals the isoelectric point (pI) of the protein. IEF PAGE gels are used to separate proteins by charge. Specialized PAGE Gels for Protein Analysis The slower mobility of proteins in Tris/tricine gels than in Tris/glycine gels results in better separation of low molecular weight polypeptides away from SDS micelles running close to the migration front. Tris/tricine PAGE gels are formulated to separate proteins and peptides with molecular weights of 10 kDa and below. Due to the lower pH, Bis-Tris gels have a longer shelf life than standard Laemmli gels. MOPS buffer is usually preferred for midsized proteins, whereas MES is used for smaller proteins. Either MES or MOPS running buffers can be used with Bis-Tris gels. This PAGE gel system has a discontinuous buffer system like Laemmli, but is run at a lower pH. Migration patterns under native conditions differ from those in denaturing gels, and molecular weight cannot be determined with accuracy.īis-Tris PAGE gels can also be used for the separation of either native or denatured proteins. Proteins separated in the absence of SDS (and usually also reducing agent) are used in protocols where proteins need to remain in a native configuration. Presence of SDS in the sample and running buffer creates denaturing conditions with separation comparable to Laemmli SDS-PAGE gels. This gives the flexibility of using a single type of gel for either separation of native or SDS-denatured proteins. Tris-HCl and Tris-acetate PAGE gels are formulated without SDS. Precast TGX and TGX Stain-Free Gels are available in the same wide range of percentages and well configurations in mini and midi formats. The ability to directly view the quality of a PAGE gel and a blot prior to further processing saves time and resources. After blotting transfer, blots can be instantly visualized to assess the efficiency of transfer and the quality of the blot. With stain-free technology, a PAGE gel can be visualized immediately after electrophoresis to confirm that sample loading is in the right range and run quality is satisfactory with no artifacts such as smiling or vertical streaking bands can be identified and excised for further analysis such as mass spectrometry. TGX Stain-Free PAGE Gels are a recent innovation providing the ability to do quality control after both electrophoresis and blotting or when locating bands for spot cutting. Precast TGX gels are available in a range of percentages, including gradient gels, with different well configurations and volumes in both mini and midi sizes. This novel SDS-PAGE gel chemistry uses the same sample separation profiles as Laemmli gels and the same sample and running buffers. These gels enable very fast run times without distortion and have a longer shelf life than standard Laemmli gels, retaining their performance and reproducibility for up to a year. TGX (Tris/Glycine eXtended) PAGE Gels are based on a modification of the Laemmli system. PAGE Gel Chemistries for Protein Separation ![]()
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