Ni-NTA Spin Kit (50)

QIAGEN offers a microspin-format system for fast, small-scale purification of His-tagged proteins. Each spin column can purify up to 300 µg of His-tagged protein, with bead sizes of 16–24 µm and approximately 25 mg of Ni-NTA silica per column. Ni-NTA silica combines Ni-NTA with a macroporous silica support material optimized to suppress nonspecific hydrophobic interactions.

The system delivers up to 95% homogeneity in one step and supports one-step purification under native or denaturing conditions. Up to 600 µl of a cell lysate is loaded onto a Ni-NTA spin column, with a quick 2-minute spin binding the tagged protein to Ni-NTA silica while most untagged proteins flow through. After a wash step, purified protein is eluted under mild conditions, such as pH reduction to 5.9, or addition of 100–500 mM imidazole, in a volume of 100–300 µl. Proteins can be purified from multiple small-scale expression cultures in around 30 minutes manually or approximately 60 minutes on the automated QIAcube Connect.

The technology relies on the selectivity of patented Ni-NTA resin for proteins containing an affinity tag of six or more histidine residues. NTA, which has four chelation sites for nickel ions, binds nickel more tightly than metal-chelating systems that have three sites available for interaction with metal ions, preventing nickel-ion leaching. The system can be used with baculovirus, mammalian cells, yeast, and bacteria, and the His tag rarely requires removal since it is small and poorly immunogenic.