Ni-NTA Superflow 96 BioRobot Kit

• Fully automated purification of up to 2 mg protein per well
• High-purity protein free from cross-contamination
• Purification under native or denaturing conditions

The Ni-NTA Superflow 96 BioRobot Kit provides automated purification of up to 300 µg recombinant protein from 96 samples in parallel (standard protocol, 5 ml culture volume per sample). Cleared bacterial cell lysates flow onto a filter plate preloaded with Ni-NTA Superflow by the BioRobot workstation. This unique 96-well metal-chelate affinity-chromatography module strongly and selectively binds His-tagged proteins. Ready-to-run protocols are provided for purification under native or denaturing conditions.

In response to customers’ needs for larger amounts of protein from automated procedures, QIAGEN has adapted the Ni-NTA Superflow 96 BioRobot protocol to enable processing of larger culture volumes and purification of up to 2 mg amounts of His-tagged protein per well. Increasing the amount of Ni-NTA Superflow resin used in the procedure to 200 µl per well and an optimized lysis buffer formulation enables up to 25 ml (purification under native conditions) or 15 ml (purification under denaturing conditions) cultures to be processed (high-yield protocols). Cell cultures are transferred to 24-well blocks for processing. The corresponding increase in biomass can deliver an increased yield of pure His-tagged protein per well (see table and figure  Milligram amounts of His-tagged proteins per well) allowing multiple assays to be carried out on the same batch of protein and reducing the total number of protein preps required, see also figure  Automated expression clone screening. The single-step purification provides highly pure proteins over a wide range of yields, and purification of large protein complexes is possible.

The QIAexpress Ni-NTA Protein Purification System, including the Ni-NTA Superflow 96 BioRobot Kit, is based on the remarkable selectivity of patented Ni-NTA (nickel-nitrilotriacetic acid) resin for proteins containing an affinity tag of six or more histidine residues — 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. (See figure  Protein purification with the Ni-NTA protein purification system).

The purification of His-tagged proteins consists of 4 stages: cell lysis, binding, washing, and elution anfd is the basis of the Ni-NTA Superflow BioRobot Kit (see figure  Ni-NTA Superflow 96 BioRobot Kit). Purification of recombinant proteins using the QIAexpress system does not depend on the 3-dimensional structure of the protein or 6xHis tag. This allows one-step protein purification under either native or denaturing conditions, from dilute solutions and crude lysates. Strong denaturants and detergents can be used for efficient solubilization and purification of receptors, membrane proteins, and proteins that form inclusion bodies. Reagents that allow efficient removal of nonspecifically binding contaminants can be included in wash buffers (see table). Purified proteins are eluted under mild conditions by adding 100–250 mM imidazole as competitor or by a reduction in pH.

The Ni-NTA Superflow 96 BioRobot Kit is for use with BioRobot 3000, 8000, or 9600 workstations. 

The QIAexpress Ni-NTA Protein Purification System provides reliable, one-step purification of proteins suitable for many application, including:

• Structural and functional investigations
• Crystallization for determination of three-dimensional structure
• Assays involving protein–protein and protein–DNA interactions
• Immunization to produce antibodies