Several lines of evidence demonstrating that Plasmodium falciparum, a parasitic organism, has distinct enzymes for the phosphorylation of choline and ethanolamine

Publisher Website
Google Scholar
Abstract
In Plasmodium falciparum-infected erythrocyte homogenates, the specific activity of ethanolamine kinase (7.6 ± 1.4 nmol phosphethanolamine/107 infected cells per h) was higher than choline kinase specific activity (1.9 ± 0.2 nmol phosphocholine/107 infected cells per h). The K m of choline kinase for choline was 79 ± 20 μM, and ethanolamine was a weak competitive inhibitor of the reaction (K i = 92 mM). Ethanolamine kinase had a K m for ethanolamine of 188 ± 19 μM, and choline was a competitive inhibitor of ethanolamine kinase with a very high K m of 268 mM. Hemicholinium 3 inhibited choline kinase activity, but had no effect on ethanolamine kinase activity. In contrast, D-2-amino-1-butanol selectively inhibited ethanolamine kinase activity. Furthermore, when the two enzymes were subjected to heat inactivation, 85% of the choline kinase activity was destroyed after 5 min at 50°C, whereas ethanolamine kinase activity was not altered. Our results indicate that the phosphorylation of choline and ethanolamine was catalyzed by two distinct enzymes. The presence of a de novo phosphatidylethanolamine Kennedy pathway in P. falciparum contributes to the bewildering variety of phospholipid biosynthetic pathways in this parasitic organism.

This publication has 31 references indexed in Scilit: