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

Abstract

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.

• Authors: Panan Kanchanaphum, Jerapan Krungkrai
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 390 Issue 2 Pg. 337-41 (Dec 11 2009) ISSN: 1090-2104 [Electronic] United States
• PMID: 19800871 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Multienzyme Complexes
• orotidylic acid
• Uridine Monophosphate
• Orotate Phosphoribosyltransferase
• Orotidine-5'-Phosphate Decarboxylase

Topics

• Animals
• Enzyme Stability
• Hot Temperature
• Humans
• Kinetics
• Malaria, Falciparum (parasitology)
• Multienzyme Complexes (antagonists & inhibitors, chemistry, genetics)
• Orotate Phosphoribosyltransferase (antagonists & inhibitors, chemistry, genetics)
• Orotidine-5'-Phosphate Decarboxylase (antagonists & inhibitors, chemistry, genetics)
• Plasmodium falciparum (enzymology)
• Uridine Monophosphate (analogs & derivatives, metabolism)