Bendy bands and what to do with them

6 minute read

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If you’ve worked with SDS-PAGE and Western blotting for a while, you’ll undoubtedly have seen bendy bands, or fuzzy bands, or both! This blog post will help you achieve those perfect razor-sharp rectangles shown on your antibody datasheet. While unattractive in their own right, these bendy bands make determining the molecular weight difficult and can interfere with band densitometry analysis, especially when using automated programs or when working with proteins that produce tight duplexes.

Fear not, here are five extremely simple steps you can take to cure the vast majority of band bending, and make your blots presentable again.

An example of some bendy bands in a precast gel from a ResearchGate post.
An example of some bendy bands in a precast gel from a ResearchGate post

Steps to Getting Rid of Bendy Bands SDS-PAGE

STEP 1: Clean your kit

You’ve spent weeks growing your rare cells, treated them with your incredibly expensive novel compound, carefully harvested and lysed your sample and then cast your gel in between two dirty smeared plates.

QUICK TIP: Clean your plates and combs! Making sure they are spotlessly clean before casting ensures your perfect gels and perfect blots.

STEP 2: Shaken, stirred...

…and left to rest! A major issue with gel casting is improper mixing of reagents, in particular the acrylamide. In order to ensure a smooth separation of proteins across your resolving gel you want to ensure a constant acrylamide percentage throughout. But equally you want to get your gels cast and on with your experiment as quickly as possible. Here, as with many things in life, more haste equals less speed.

QUICK TIP: A thorough mixing of gel reagents, followed by the equally important degassing step, will give you pristine gels first time, every time.

STEP 3: Fresh is best

We often have breaks in our Western blotting, and whilst it’s tempting to reach for that 6 month old bottle of running buffer, which has been sitting in the sun, it probably makes more sense to throw it out and start again. At the very least checking the pH of your stacking and resolving gel reagents is a must as this plays a fundamental role in how your proteins migrate through the gel.

QUICK TIP: It’s worth keeping on top of your buffers and ensuring they’re fresh. This guaranties they have the correct pH.

Bendy bands SDS Page
Oddly shaped bands from ResearchGate

STEP 4: Slow and steady

We know you want to get your exciting results ASAP, but running your gels with a high voltage might leave you having to cast and re-run your samples again.

QUICK TIP: Forcing your samples through the stack too quickly can mean they hit the resolving gel spread out, rather than in a nice tight line. The same is true in the resolving gel, by running your gels at too high a voltage the buffers and your gels become hot, and this is a major contributor to warping and bending in your gel.

STEP 5: More isn’t always better

Less about bending and more about blotting, this step is vital in ensuring you get the most accurate results possible from your blotting. While it’s tempting to load the maximum concentration of protein in the maximal volume, sometimes it’s worth reducing the load to ensure you get a nice sharp band rather than an unintelligible blot. 

QUICK TIP: With new antibodies, and even new antibody batches, it’s always worth running a test with a standard curve of total protein. This simple step can save you sample, and time as it makes your analysis quicker and easier too.

Following these five steps will help you keep your bands razor sharp. They’ll be the pride of your lab-book, rather than something to leave tucked away in the back of your drawer. While you’re here, watch out for these assumptions about SDS-PAGE from our friends at NanoTemper.

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