The human immunodeficiency virus type-1 (HIV-1) integrase (IN) catalyzes the insertion of the retroviral genome into the chromosome of an infected host cell. HIV-1 IN was expressed as a N-terminal hexa-histidine fusion in Escherichia coli. A high-throughput purification strategy was developed using denaturing methods for the initial protein extraction, followed by a one-step nickel-chelating chromatography purification and step-wise refolding. IN was routinely greater than 90% pure with yields exceeding 14 mug of purified IN Per ml of E coli culture. In vitro 3' processing and strand transfer assays showed the enzyme preparations to be highly active. The specific activity of the purified IN was 2.65 pmol/h/mug IN, which is very similar to the activity of IN routinely produced by large-scale column chromatographic methods. This high-throughput platform should be of general utility to those interested in defining the structure-function relationship of proteins and enzymes. (C) 2003 Elsevier Inc. All rights reserved.