A competitive assay for rapid screening for His-tagged proteins.

• A semi-quantitative screening assay to detect His-tagged proteins from cell lysates or affinity column fractions
• An alternative to SDS-PAGE for testing affinity column fractions
• Assay 26 samples in triplicate or 39 samples in duplicate
• Rapid assay; get results in under three hours

Recombinant proteins are routinely labeled with affinity tags, such as hexahistidine (6X-His), GST and FLAG, to facilitate both their detection and purification. 6X-His tags are often the tag of choice due to their small size, less potential to interfere in protein folding, weak immunogenicity, and high affinity for Ni2+. Cell lysates and samples at different stages of purification are generally analyzed by SDS-PAGE, a process which can add several days to the purification and analysis protocol. A semi-quantitative screening assay provides the ability to rapidly assess the levels His-tagged proteins at each stage of the expression and purification process. This permits the user to quickly monitor expression efforts, as well as follow protein loss or enrichment at each purification step. Cayman’s His-Tag Detection ELISA Kit is competitive assay designed for the rapid, semi-quantitative screening of cell lysates and affinity column fractions for His-tagged proteins. It is intended to serve as a substitute for SDS-PAGE, thereby expediting the screening of affinity column fractions.