Kinetic benefits and thermal stability of orotate phosphoribosyltransferase and orotidine 5′-monophosphate decarboxylase enzyme complex in human malaria parasite Plasmodium falciparum

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• 作者：Panan Kanchanaphum ; Jerapan Krungkrai
• 关键词：Orotate phosphoribosyltransferase ; Orotidine 5′ ; -monophosphate decarboxylase ; Enzyme complex ; Malaria ; Plasmodium falciparum
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2009
• 出版时间：11 December 2009
• 年：2009
• 卷：390
• 期：2
• 页码：337-341
• 全文大小：332 K

文摘

We have previously shown that orotate phosphoribosyltransferase (OPRT) and orotidine 5′-monophosphate decarboxylase (OMPDC) in human malaria parasite Plasmodium falciparum form an enzyme complex, containing two subunits each of OPRT and OMPDC. To enable further characterization, we expressed and purified P. falciparum OPRT–OMPDC enzyme complex in Escherichia coli. The OPRT and OMPDC activities of the enzyme complex co-eluted in the chromatographic columns used during purification. Kinetic parameters (K_m, k_cat and k_cat/K_m) of the enzyme complex were 5- to 125-folds higher compared to the monofunctional enzyme. Interestingly, pyrophosphate was a potent inhibitor to the enzyme complex, but had a slightly inhibitory effect for the monofunctional enzyme. The enzyme complex resisted thermal inactivation at higher temperature than the monofunctional OPRT and OMPDC. The result suggests that the OPRT–OMPDC enzyme complex might have kinetic benefits and thermal stability significantly different from the monofunctional enzyme.