The HIS-Select iLAP (Integrated Lysis and Affinity Purification) Columns combine cell lysis and protein purification steps into one. These single-use, disposable columns are designed for the one-step purification of histidine-tagged proteins directly from a 5 mL bacterial culture. The single-step method uses Sigma's patented iLAP technology, which allows quick and simple histidine-tagged protein purification from recombinant clones. Each column contains nickel chelate resin for the purification, as well as five lysis reagent tablets, which include all the necessary detergents and enzymes needed for efficient cell lysis and protein extraction while eliminating the need to harvest the cells from culture. Each column is capable of purifying at least 1 mg of histidine-tagged protein directly from 5 mL of bacterial culture in less than one hour. The procedure provided can be used to extract soluble proteins directly from growing cells and results in a nearly pure fusion protein preparation following elution from the column. This makes these columns ideal for confirming expression of a histidine-tagged target protein, for performing protein-protein interaction assays, or for rapidly screening colonies or multiple constructs (cultures). The resulting purified protein is compatible with protein assays, SDS-PAGE, Western blotting, and MALDI.