PURIFICATION AND CRYSTALLIZATION OF RECOMBINANT LACTATE DEHYDROGENASE OF PLASMODIUM FALCIPARUM. Debasish Chattopadhyay, Dwight Moore, Patrick Campbell, David Bzik* , Barabara A. Fox*, Lawrence J. DeLucas & Sthanam V. L. Narayana. Center for Macromolecular Crystallography, University of Alabama at Birmingham, 1918 University Blvd. Birmingham, AL 35294; *Department of Microbiology, Dartmouth-Hitchcock Medical Center, Hanover, NH 03755.

Infection with the malaria parasites is one of the major infectious causes of mortality in worldwide. Management of the infection is increasingly compromised by the incessant spread of drug resistance. It is necessary to identify new exploitable therapeutic targets and discover potential inhibitors for these targets. Lactate dehyrogenase enzyme of malaria parasite plays an important role in regulating glycolysis. The enzyme possesses distinctive features in its physicochemical and biochemical properties as compared to the host enzyme. We have purified a recombinant lactate dehydrogenase (LDH) of Plasmodium falciparum to explore the possibility of using this enzyme as a target for structure based drug design. Protein is purified from the soluble extract of Escherichia coli using anion exchange chromatography on Q-Sepharose followed by chromatography on Blue Sepharose and HPLC gel filtration. Purified protein is active in an NADH dependent LDH assay. The protein is crystallized using hanging drop vapor diffusion technique with PEG 20,000 as precipitant at pH 6.3 -6.7 and 10% (v/v) glycerol as an additive.