I am transferring a Tris-Glycine gel using constant voltage and the current reading is way over the expected starting current. Can you offer some suggestions?
The most common cause of abnormally high current is the transfer buffer. If the transfer buffer is too concentrated, this leads to increased conductivity and current. High current may also occur if Tris-HCl is accidentally substituted for the Tris base required in the transfer buffer. This will again result in low buffer pH and lead to increased conductivity and current and subsequently, overheating. We recommend checking the transfer buffer and its reagent components and re-diluting or remaking the buffer.
Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.
What are the main advantages of NuPAGE gels over Invitrogen Tris-Glycine gels?
NuPAGE gels have the following advantages over Tris-Glycine gels:
*Higher stability and longer shelf life: NuPAGE Bis-Tris gels and NuPAGE Tris-Acetate gels have a lower operating pH (pH 7 for NuPAGE Bis-Tris gels and pH 8.1 for NuPAGE Tris-Acetate gels) than Invitrogen Tris-Glycine gels (pH 9.5). At basic pH, polyacrylamide hydrolyzes to polyacrylic acid and ammonia whereas at neutral pH, this hydrolysis is slower. Hence, NuPAGE gels have higher stability and longer shelf life than Invitrogen Tris-Glycine gels (12 months at 4-25 degrees C for NuPAGE Bis-Tris gels and 8 months at 4 degrees C for NuPAGE Tris-Acetate gels vs 4-8 weeks at 4 degrees C for Tris-Glycine gels).
*Better resolution of proteins due to:
- Reduced undesired chemical modifications: Free acrylamide alkylates proteins at basic pH (8.5 to 9.0). It targets sulfhydryl cysteines and amine groups at the N-terminus and on lysines. This modification does not happen at pH below 8. Hence, proteins run on NuPAGE gels undergo fewer of these undesired chemical modifications than those run on Tris-Glycine gels.
- Reduced hydrolysis of proteins: Heating of Tris-Glycine sample buffer (pH 6.8) results in a drop in pH, causing Asp-Pro cleavage of proteins. High temperature and longer duration of heating/boiling increase the rate of this cleavage resulting in multiple peptide bands of decreased intensity. At 100 degrees C, the pH drops as low as pH 4.3. On the other hand, NuPAGE LDS sample buffer (pH 8.5) drops to pH 8.1 when heated to 70 degrees C, avoiding this cleavage.
*Faster run times: 35-50 min for NuPAGE Bis-Tris gels and 1 hour for NuPAGE Tris-Acetate gels vs 90 min for Tris-Glycine gels
Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.
How does the operating pH for Tris-Glycine gels differ from that for NuPAGE Bis Tris and NuPAGE Tris-Acetate gels?
The operating pH for Tris-Glycine gels is 9.5; the operating pH for NuPAGE Bis-Tris gels is 7 and for NuPAGE Tris-Acetate gels is 8.1.
Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.
Can I run Mini gels with 10 cm gel cassettes using a Bolt Mini Gel Tank?
To run Mini gels with 10 cm gel cassettes using a Bolt Mini Gel Tank (without replacement of 10.5 cm cassette clamp cam handles with 10 cm cassette clamp cam handles), please use the instructions provided on Page 22 of the manual (https://tools.thermofisher.com/content/sfs/manuals/mini_gel_tank_man.pdf).
Note: For optimal results, to run 10 cm cassette Mini gels with a Bolt Mini Gel Tank, one should replace the black 10.5 cm cassette clamp cam handles on the Bolt Mini Gel Tank with gray 10 cm cassette clamp cam handles (Cat. No. A26732). Instructions for replacement of the cam handles can be found on Page 20 of the manual (http://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-gel-electrophoresis/protein-gel-electrophoresis-chamber-systems/mini-gel-tank/resources-upgrading-bolt-mini-gel-tank.html) or in this video (https://www.youtube.com/watch?v=1FtiX8Skllw).
Additional resources can be found here (https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-gel-electrophoresis/protein-gel-electrophoresis-chamber-systems/mini-gel-tank/resources-upgrading-bolt-mini-gel-tank.html).
Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.
How do you recommend transferring Midi gels?
Midi gels can be transferred using:
*iBlot Dry Blotting System in conjunction with Transfer Stacks
*Invitrogen Semi-Dry Blotter for simultaneous transfer of up to 2 Midi-gels
*Thermo Scientific Power Blotter for simultaneous transfer of up to 2 Midi gels
*Thermo Scientific G2 Fast Blotter (will be discontinued as soon as we exhaust current inventory).
Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.
