In a paper published online August 22 in the journal Nature, Ryan Jensen, Ph.D., postdoctoral researcher at the University of California, Davis, and his colleagues reported the first purification of full-length BRCA2 protein. The protein, mutations of which lead to breast and ovarian cancers, has eluded research groups for years due to challenges preventing its purification.
Like many researchers, Dr. Jensen used his own handcast polyacrylamide gels to monitor the purification of BRCA2. During many of these attempts, the higher molecular weight proteins—including BRCA2—were undetectable.
When Dr. Jensen began using Bio-Rad Laboratories’ Mini-Protean TGX long shelf life gels, he consistently observed “tight, crisp” bands corresponding to BRCA2. “When I hand poured my gels to analyze the purification of BRCA2, I wasn’t always confident that it would show up,” Dr. Jensen said. “With Bio-Rad’s TGX gels, I can count on the fact that BRCA2 will show up every time.”
Since the late 1960s, the SDS-PAGE workflow has become a widely used tool for analyzing protein mixtures. Within that workflow, the Laemmli system is regarded as the gold standard for SDS-PAGE techniques. Utilizing a Tris-glycine-SDS buffer system, the Laemmli system has the ability to clearly resolve and provide accurate molecular weight estimation of proteins in complex samples from a wide variety of sources.
Researchers looking to use the Laemmli system have two options for gels: handcast gels and precast gels. Handcasting polyacrylamide gels is time-consuming and often leads to inconsistent results. Handcast gels must also be used immediately. In their favor, handcast gels run on the standard Laemmli buffer system and serve as an inexpensive option for cost-conscious labs.
Commercially available precast gels, on the other hand, save researchers from the time and hassle of handcasting. However, precast gels with longer shelf lives typically require the use of alternative buffer systems such as MOPS or MES that present different electrophoretic patterns, affecting both the resolution and banding patterns of proteins in complex mixtures.
Specialized buffer systems also usually cost more per run, so given the widespread use of SDS-PAGE, this can have a significant adverse impact on a laboratory’s budget.
Precast gels that utilize standard buffers face the disadvantage of the traditional Laemmli systems’ loss of gel matrix stability, resulting in a shelf life of only a few months. Gel performance steadily degrades over time, reducing resolution and sensitivity, and increasing time-to-results.
In response to these and other challenges, Bio-Rad introduced Mini-Protean TGX long shelf life gels. These long shelf life gels are based on a novel modification of the Laemmli system, and offer advantages over both handcast and other precast gels in terms of consistency, speed, and reproducibility.