NuPAGE™ MOPS SDS Buffer Kit (for Bis-Tris Gels) - FAQs

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15 product FAQs found

Can I prepare my protein sample with the reducing agent and store it for future use?

DTT is not stable, so it must be added and the reduction performed just prior to loading your samples.

Find additional tips, troubleshooting help, and resources within our Protein Gel 1D Electrophoresis Support Center.

My LDS or SDS sample buffer precipitates when stored at 4 degrees C. Can I warm it up? Can I store it at room temperature?

Precipitation of the LDS or SDS at 4 degrees C is normal. Bring the buffer to room temperature and mix until the LDS/SDS goes into solution. If you do not want to wait for it to dissolve, you can store the sample buffer at room temperature.

Find additional tips, troubleshooting help, and resources within our Protein Gel 1D Electrophoresis Support Center.

How are Bolt gels different than NuPAGE gels?

While they are both Bis-Tris based gels, the chemistries are very different since Bolt gels are optimized for western blotting. Another key difference is the wedge well design of the Bolt gels, which allows larger sample volumes to be loaded.

Find additional tips, troubleshooting help, and resources within our Protein Gel 1D Electrophoresis Support Center.

What is the advantage of NuPAGE Gels over regular Tris-Glycine gels?

The neutral operating pH of the NuPAGE Gels and buffers provides following advantages over the Laemmli system:
-Longer shelf life of 8-12 months due to improved gel stability
-Improved protein stability during electrophoresis at neutral pH resulting in sharper band resolution and accurate results (Moos et al, 1998)
-Complete reduction of disulfides under mild heating conditions (70 degrees C for 10 min) and absence of cleavage of asp-pro bonds using the NuPAGE LDS Sample buffer (pH > 7.0 at 70 degrees C)
-Reduced state of the proteins maintained during electrophoresis and blotting of the proteins by the NuPAGE Antioxidant
Please refer to the following paper: Moos M Jr, Nguyen NY, Liu TY (1988) Reproducible High Yield Sequencing of Proteins Electrophoretically Separated and Transferred to an Inert Support. J Biol Chem 263:6005-6008.

Find additional tips, troubleshooting help, and resources within our Protein Gel 1D Electrophoresis Support Center.

Can beta-mercaptoethanol (BME) be used rather than DTT as the reducing agent in the NuPAGE LDS Sample Buffer?

Either BME or DTT can be used in the NuPAGE LDS Sample Buffer.

Make sure that a fresh solution of BME is used. FINAL concentration:

DTT 50-100 mM

BME 2-5%

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Can I use CTAB rather than SDS in my sample buffer?

No, CTAB will not work with any of our gels except for the NuPAGE Tris-Acetate gels. To use CTAB, you would need to use a running buffer of 50 mM acetic acid and 50 mM beta-alanine in equal concentrations. You would also need to switch the electrodes. Since CTAB is a cationic detergent, this would establish conditions for running a basic protein towards the anode (into the gel).

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Is there a reasonable replacement for the NuPAGE antioxidant for gel electrophoresis?

One can use 0.002% thioglycolic acid in the upper buffer reservoir. This is a good scavenger of free radicals. The reference to this is described by Hunkapiller et al, Methods of Enzymology, (91), 399, 1983. Caution should be taken when using this method since this compound is both toxic and expensive. In addition, the TGA must be fresh as it tends to become oxidized itself over time. Oxidized TGA will actually promote sample re-oxidation.

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Do you have recommended protocols for copper or zinc staining of NuPAGE gels?

Copper or zinc staining is a rapid, sensitive method for detection of protein bands . ~10 ng reduced BSA on NuPAGE Bis-Tris gels can be detected with both the copper and zinc stain.

Copper Stain: Staining solution - 0.3 M CuCl2
After electrophoresis, remove the gel from the cassette and equilibrate the gel in 100 mL of 1X running buffer* for 15 minutes. Immerse the gel in 100 ml of 0.3 M CuCl2 solution for about 5 minutes (the protein band will appear as a negative stain with a blue background).

Zinc stain: Staining solution - 0.2 M Imidazole and 10 mM ZnCl2
After electrophoresis, remove the gel from the cassette and equilibrate the gel in 100 mL of 1X running buffer* for 15 minutes. Place the gel in 100 ml of 0.2M Imidazole solution for 10 minutes. Next immerse the gel in 100 ml of 10 mM ZnCl2 solution for about 5 minutes (the protein will appear as a transparent band with a white background).

*The 1X running buffer can be the buffer from the electrophoresis tank after run (MES, MOPS). However, for better contrast of the band, the 1X Tris-Glycine SDS running buffer is recommended.

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Is it okay to use protein gels past their expiration date?

We do not recommend using gels past their expiration date because over time, the polyacrylamide hydrolyzes to acrylic acid and ammonia and this will affect the resolution of the proteins. Breakdown of polyacrylamide matrix is identified by:
- Ghost bands and doublets, seen first in the high molecular weight proteins
- Smiling of dye front across the gel, with bands in outer lanes becoming very slanted - proteins run slower there due to change in pH and pore size over time.


Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Can I run your protein gels overnight?

This is not really recommended, but it is always possible to increase run time by lowering the voltage of the run. In general, the relationships are linear - i.e., decreasing voltage by half will double the run time.

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Do I need to increase the voltage when I run a 1.5 mm protein gel versus a 1.0 mm gel?

If you are running the gel at constant voltage, you do not need to increase the voltage regardless of the thickness of the gel.

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Why do you recommend running your protein gels at constant voltage?

Using constant voltage allows the current and power to decrease during the run, providing a safety margin in case of a break in the system. Having lower power is a safety benefit and will also decrease the chances of experiencing an overheating of the gel. Further, the constant voltage setting does not need adjustment to account for differences in number or thickness of gels being run.

Find additional tips, troubleshooting help, and resources within ourProtein Gel 1D Electrophoresis Support Center.

How should I store the NuPAGE buffers?

NuPAGE buffers can be stored at 4-25 degrees C.

Find additional tips, troubleshooting help, and resources within our Protein Gel 1D Electrophoresis Support Center.

What are the recommended sample loading volumes and protein loading amounts for your precast protein gels?

*Tris-Glycine and Invitrogen Tricine Mini gels: see here (http://tools.thermofisher.com/content/sfs/manuals/electrophoresisguide_man.pdf), Page 8

*NuPAGE Tris-Acetate and NuPAGE Bis-Tris Mini gels: see here (http://tools.thermofisher.com/content/sfs/manuals/nupage_tech_man.pdf), Page 10

*Bolt Bis-Tris Plus Mini gels: see here (http://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-gel-electrophoresis/protein-gels/bolt-bis-tris-gels.html)

*Thermo Scientific Precise Tris-HEPES gels: see here (https://tools.thermofisher.com/content/sfs/manuals/MAN0011499_Precise_Protein_Gels_UG.pdf), Page 1

*Midi gels (Invitrogen Tris-Glycine, NuPAGE Bis-Tris and NuPAGE Tris-Acetate): see here (https://assets.thermofisher.com/TFS-Assets/LSG/manuals/novex_midigel_man.pdf), Page 4

*Thermo Scientific Precise Tris-Glycine gels: see here (https://tools.thermofisher.com/content/sfs/manuals/D25MAN0011814_Precise_TrisGlycine_Gels_UG.pdf), Page 1

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Do your precast protein gels contain SDS?

Our precast protein gels do not contain SDS but they can be run under denaturing conditions when used with the appropriate denaturing running buffer.
Note: NuPAGE Bis-Tris gels, Bolt Bis-Tris Plus gels, and Thermo Scientific Precise Tris-HEPES gels cannot be run under native conditions; they can only be run under denaturing conditions.

*Invitrogen Tris-Glycine gels: For Native electrophoresis, use Invitrogen Tris-Glycine Native Running Buffer. For Denaturing electrophoresis, use Invitrogen Tris-Glycine SDS Running Buffer

*NuPAGE Tris-Acetate gels: For Native electrophoresis, use Invitrogen Tris-Glycine Native Running Buffer. For Denaturing electrophoresis, use NuPAGE Tris-Acetate SDS Running Buffer

*NuPAGE Bis-Tris gels: For Denaturing electrophoresis, use NuPAGE MOPS-SDS Running Buffer or NuPAGE MES-SDS Running Buffer

*Bolt Bis-Tris Plus gels: For Denaturing electrophoresis, use Bolt MOPS SDS Running Buffer or Bolt MES SDS Running Buffer

*Thermo Scientific Precise Tris-Glycine gels: For Native electrophoresis, use Tris-Glycine SDS Running Buffer without SDS added. For Denaturing electrophoresis, use Tris-Glycine SDS Running Buffer.

*Thermo Scientific Precise Tris-HEPES gels: For Denaturing electrophoresis, use Tris-HEPES SDS Running Buffer.

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.