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Several lines of evidence demonstrating that Plasmodium falciparum , a parasitic organism, has distinct enzymes for the phosphorylation of choline and ethanolamine
Author(s) -
Ancelin Marie L.,
Vial Henri J.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80690-1
Subject(s) - choline kinase , ethanolamine , choline , biochemistry , kinase , biology , enzyme , phospholipid , phosphocholine , chemistry , phosphatidylcholine , membrane
In Plasmodium falciparum ‐infected erythrocyte homogenates, the specific activity of ethanolamine kinase (7.6 ± 1.4 nmol phosphethanolamine/10 7 infected cells per h) was higher than choline kinase specific activity (1.9 ± 0.2 nmol phosphocholine/10 7 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.