Bio-Rad’s New 4x Laemmli Sample Buffer for SDS-PAGE

Detecting proteins in dilute samples can be problematic. Approaches that allow higher sample loads on SDS-PAGE gels are valuable for detection.

The newly introduced 4x Laemmli sample buffer enables the detection of dilute samples by effectively increasing the sample load volume by 50%. For example, in a 50 μl-well gel the sample load increases to 37.5 μl vs. 25 μl when used with the 2x sample buffer. This enables the visualization of dilute samples that otherwise cannot be detected by standard protein gel stains.

An additional method of enabling increased sample capacity on gels is to use an increased well size from the standard 30 μl-well format. Bio-Rad^® offers Mini-PROTEAN^® gels in 10 well, 50-μl formats and Criterion™ gels in the 12+2 well, 45-μl formats. The 4x Laemmli sample buffer, in combination with these gels, allows a larger amount of protein to be loaded than when using smaller well types and more dilute sample buffers, which improves detection of low-abundance targets.

The new 4x Laemmli sample buffer can be used directly for nonreducing conditions or with the addition of reducing agent for reducing conditions. The 4x Laemmli sample buffer is optimized for use with Laemmli gels, which includes Mini-PROTEAN^® TGX™ and Mini-PROTEAN^® TGX Stain-Free™ precast gels, Criterion™ TGX™ and Criterion™ TGX Stain-Free™ precast gels, Criterion Tris-HCI precast gels, Ready Gel^® Tris-HCI precast gels as well as traditional handcast Tris-HCI gels.

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