For purification of His-tagged proteins by gravity-flow chromatography
Ni-NTA Agarose is an affinity chromatography matrix for purifying recombinant proteins carrying a His tag. Histidine residues in the His tag bind to the vacant positions in the coordination sphere of the immobilized nickel ions with high specificity and affinity. Cleared cell lysates are loaded onto the matrices. His-tagged proteins are bound, and other proteins pass through the matrix. After washing, His-tagged proteins are eluted in buffer under native or denaturing conditions.
Ni-NTA Agarose provides Ni-NTA coupled to a Sepharose CL-6B support and offers high binding capacity and minimal nonspecific binding (see figure One-step purification under native conditions). This material has excellent handling properties for most scales of batch and column purification. Ni-NTA Agarose is available separately or as a component of QIAexpress Kits, which are complete kits for efficient expression and purification of His-tagged proteins from E. coli .
The QIAexpress Ni-NTA Protein Purification System is based on the remarkable selectivity of patented Ni-NTA (nickel-nitrilotriacetic acid) resin for proteins which contain an affinity tag of six or more histidine residues (consecutive or alternating) — the His tag. This technology allows one-step purification of almost any His-tagged protein from any expression system under native or denaturing conditions. NTA, which has four chelation sites for nickel ions, binds nickel more tightly than metal-chelating purification systems that only have three sites available for interaction with metal ions. The extra chelation site prevents nickel-ion leaching and results in a greater binding capacity and protein preparations with higher purity than those obtained using other metal-chelating purification systems. The QIAexpress system can be used to purify His-tagged proteins from any expression system, including baculovirus, mammalian cells, yeast, and bacteria.
Ni-NTA matrices provide reliable, one-step purification of His-tagged proteins suitable for any application, including: