Leishmaniasis is considered by the World Health Organization to be the second most important disease caused by a protozoan parasite. Biochemical and molecular biology studies can help in the understanding of the biology of the Leishmania parasite.  All protozoan parasites, including Leishmania, are unable to synthesize purines de novo, and nucleoside diphosphate kinases are involved in the salvage pathway by which free purines are converted to nucleosides and subsequentely to nucleotides. The nucleoside diphosphate kinase (EC 2.7.4.6; NDK) catalyses the transfer of the g-phosphoryl group from a nucleoside triphosphate to a nucleoside diphosphate by a ping-pong mechanism involving a phosphohistidine intermediate state.  The region containing the NDK coding sequence was amplified from L. major genomic DNA by PCR and cloned into the pT7T3 and pET28a vectors.  The pET28aNDK construct were used for protein expression in E. coli BL21(DE3)pLysS and the recombinant NDK (rNDK) containing a His₆-tag was expressed as soluble form and subsequently purified from the cell lysate by affinity chromatography using a Ni-NTA resin.  The secondary and tertiary structure of the rNDK was evaluated by circular dichroism and intrinsic tryptophan fluorescence spectroscopy respectively.  The presence of rNDK phosphotransferase activity was detected by the chromatographic separation of donor (ATP), acceptor (GDP) and produced (GTP) nucleotides.  The activity of the rNDK was further evaluated using a pyruvate kinase/lactate dehydrogenase-coupled method that detects ADP as product of the phosphotransfer reaction between ATP to dTDP nucleotides.  The purification yield showed that 47,2% of total activity was retained by the Ni-NTA column, yielding a final activity purification of 82 fold.