tailieunhanh - Báo cáo khoa học: An a-proteobacterial type malate dehydrogenase may complement LDH function in Plasmodium falciparum Cloning and biochemical characterization of the enzyme

Malate dehydrogenase (MDH) may be important in car-bohydrate and energymetabolism inmalarial parasites. The cDNA corresponding to the MDHgene, identified on chromosome 6 of thePlasmodium falciparumgenome, was amplified by RT-PCR, cloned and overexpressed in Escherichia coli. The recombinant PfMDH was purified to homogeneity and biochemically characterized as an NAD + (H)-specific MDH, which catalysed reversible inter-conversion of malate to oxaloacetate. | Eur. J. Biochem. 271 3488-3502 2004 FEBS 2004 doi An a-proteobacterial type malate dehydrogenase may complement LDH function in Plasmodium falciparum Cloning and biochemical characterization of the enzyme Abhai K. Tripathi1 Prashant V. Desai2 Anupam Pradhan1 Shabana I. Khan1 Mitchell A. Avery1 2 Larry A. Walker1 3 and Babu L. Tekwani1 National Center for Natural Product Research Research Institute of Pharmacological Sciences department of Medicinal Chemistry and 3Department of Pharmacology School of Pharmacy University of Mississippi MS USA Malate dehydrogenase MDH may be important in carbohydrate and energy metabolism in malarial parasites. The cDNA corresponding to the MDH gene identified on chromosome 6 of the Plasmodium falciparum genome was amplified by RT-PCR cloned and overexpressed in Escherichia coli. The recombinant Pf MDH was purified to homogeneity and biochemically characterized as an NAD H -specific MDH which catalysed reversible interconversion of malate to oxaloacetate. Pf MDH could not use NADP NADPH as a cofactor but used acetylpyridine adenine dinucleoide an analogue of NAD. The enzyme exhibited strict substrate and cofactor specificity. The highest levels of Pf MDH transcripts were detected in trophozoites while the Pf MDH protein level remained high in trophozoites as well as schizonts. A highly refined model of Pf MDH revealed distinct structural characteristics of substrate and cofactor binding sites and important amino acid residues lining these pockets. The active site amino acid residues involved in substrate binding were conserved in Pf MDH but the N-terminal glycine motif which is involved in nucleotide binding was similar to the GXGXXG signature sequence found in Pf LDH and also in a-proteobacterial MDHs. Oxamic acid did not inhibit PfMDH while gossy-pol which interacts at the nucleotide binding site of oxido-reductases and shows antimalarial activity inhibited PfMDH also. Treatment of a synchronized .