Ni-NTA Fast Start Kit (6)

Designed by QIAGEN for the purification and detection of recombinant His-tagged proteins from E. coli lysates, this kit relies on Ni-NTA (nickel-nitrilotriacetic acid) resin to deliver reliable, one-step purification of 6xHis-tagged proteins under native or denaturing conditions. The NTA moiety binds nickel through four chelation sites, preventing nickel-ion leaching and yielding protein preparations of higher purity than metal-chelating systems with fewer chelation sites. The kit is suitable for any downstream application and includes Penta·His Antibody, which recognizes the His tag as its epitope.

Ni-NTA matrix is the support, processing is manual, and the format is gravity flow, with a binding capacity of 5–20 mg/ml and a yield of less than 10 mg protein per column. The interaction between the 6xHis tag and Ni-NTA matrices is conformation independent, and binding, washing, and elution are highly reproducible with no effect on protein structure, so eluted proteins are ready for direct use in downstream applications. The 6xHis tag is small, uncharged at physiological pH, and poorly immunogenic, allowing the recombinant protein to be used as an antigen without prior tag cleavage; Factor Xa Protease can also be used to remove the tag where removal is preferred, for example for crystallographical or NMR studies.

The elution buffer supplied with the kit is 50 mM Na-phosphate, 300 mM NaCl and 250 mM imidazole at pH 8.0. The kit's buffers are based on the recipes in the QIAexpressionist handbook, with specific components added for optimized performance; the exact composition is confidential, although the buffers listed in the QIAexpressionist appendix are compatible.