Invitrogen’s precast NuPAGE electrophoresis system is a windfall for anyone that has poured their own gels and buffers for traditional PAGE systems. NuPAGE eliminates all the problems with uneven or incomplete polymerization, leakage, and reproducibility that occur when making your own buffers and gels. NuPAGE gels also come in a range of formulations, that when combined with preoptimized buffers, can be used to separate any size range of proteins.
The NuPAGE Novex system has several components that can be tricky to sort out when first setting up this system. You will need to purchase the XCell Surelock™ Mini- or Midi-cell to run the gels. Optional equipment includes the XCell II™ Blot module for the transfer and the Powerease 500 power programmable power supply. We do not use the X-Cell blot module. Instead we use our old Bio-Rad transfer apparatus with the NuPAGE transfer buffer. It works perfectly well for transferring all the Bis-Tris gels types. We do use the Powerease 500, but just as often use our other power supplies to run the gels with comparable results. The programmable feature is nice, because it offers auto shut-off if you need to attend a seminar or class while your gel is running or transferring.
Once the running/blotting system is set up, you will need to choose a gel and buffer system. Gels come as Bi-Tris (7%, 10%, 3-8% discontinuous or 4-12% discontinuous) or Tricine (10% or 4-12% discontinous) with many months of shelf life. The Invitrogen website has a handy chart to show you which gels you need depending on what percentage of Tris-Gly or Tricine gel you currently use. Alternatively, if you are just starting, the website also shows the separation of standard molecular weights for each type of gel in the preoptimized MES or MOPS running buffers. In our lab we get better resolution of bands with NuPAGE gels than homemade gels. You can also make your own MES, MOPS, or NuPAGE transfer buffer, but we have priced out the components and it is less expensive as well as more convenient to purchase these buffers premade through our Invitrogen representative. The gels on the other hand, are more expensive to buy premade than buying the components to make your own. However, they save you hours of time and are 100% reliable. We have only ever had one problem running a NuPAGE gel, and later found out it was an expired gel.
Luckily, the only other component you need to purchase from Invitrogen is the NuPage Antioxidant. You can actually make this yourself. This is added to the buffer in the top chamber of the gel. We also like to purchase the LDS sample loading buffer and stabilized NuPAGE Sample Reducing Agent, again for the reproducibility. However, our homemade Laemmli sample buffer also works with these gels. The samples just run slightly differently relative to the ladder.
Overall, this system is worth every penny to our lab for its reliability and reproducibility. If you are setting up a new lab or doing Western blotting on a regular basis, seriously consider investing in this system for smoother operations and long term cost effectiveness.