Comparative Structural Analysis and Kinetic Properties of Lactate Dehydrogenases from the Four Species of Human Malarial Parasites
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- 作者：W. Michael Brown ; Charles A. Yowell ; Anna Hoard ; Thomas A. Vander Jagt ; Lucy A. Hunsaker ; Lorraine M. Deck ; Robert E. Royer ; Robert C. Piper ; John B. Dame ; Michael T. Makler ; and David L. Vander Jagt
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：May 25, 2004
- 年：2004
- 卷：43
- 期：20
- 页码：6219 - 6229
- 全文大小：286K
- 年卷期：v.43,no.20(May 25, 2004)
- ISSN：1520-4995
文摘
Parasite lactate dehydrogenase (pLDH) is a potential drug target for new antimalarials owingto parasite dependence on glycolysis for ATP production. The pLDH from all four species of humanmalarial parasites were cloned, expressed, and analyzed for structural and kinetic properties that might beexploited for drug development. pLDH from Plasmodium vivax, malariae, and ovale exhibit 90-92%identity to pLDH from Plasmodium falciparum. Catalytic residues are identical. Resides I250 and T246,conserved in most LDH, are replaced by proline in all pLDH. The pLDH contain the same five-aminoacid insert (DKEWN) in the substrate specificity loops. Within the cofactor site, pLDH from P. falciparumand P. malariae are identical, while pLDH from P. vivax and P. ovale have one substitution. Homologymodeling of pLDH from P. vivax, ovale, and malariae with the crystal structure of pLDH from P.falciparum gave nearly identical structures. Nevertheless, the kinetic properties and sensitivities to inhibitorstargeted to the cofactor binding site differ significantly. Michaelis constants for pyruvate and lactate differ8-9-fold; Michaelis constants for NADH, NAD+, and the NAD+ analogue 3-acetylpyridine adeninedinucleotide differ up to 4-fold. Dissociation constants for the inhibitors differ up to 21-fold. Moleculardocking studies of the binding of the inhibitors to the cofactor sites of all four pLDH predict similarorientations, with the docked ligands positioned at the nicotinamide end of the cofactor site. pH studiesindicate that inhibitor binding is independent of pH in the pH 6-8 range, suggesting that differences indissociation constants for a specific inhibitor are not due to altered active site pK values among the fourpLDH.