[In vitro decrease of the cytolytic effect of E. histolytica by inhibition of its phosphofructokinase].
The C14 radioactive label of PPi analogues was incorporated to E. histolytica after 24 hours of incubation at 37 degrees C; more than 90% of trophozoites remained viable. The PPi dependent phosphofructokinase was isolated in order to determine its kinetic parameters. With PPi, the Km was 18.06 +/- 0.91 micromol/mL-1. Using three different PPi analogues (tetrasodium salts) of (I) 1,1 hydroxy-methyl diphosphonate; (II) 1,1 hydroxy ethylene diphosphonate; (III) 1,1 hydroxy-nonano diphosphonate, KiI was 35.19 +/- 1.74; KiII was 42.65 +/- 0.65, and KiIII 2as 62.81 +/- 0.27 micromol/mL-1. The graphic expression of these results shows that the enzyme was competitively inhibited by the three analogues. When trophozoites were incubated with each one of the three inhibitors, a correlation was observed between the concentration and the cytolytic inhibition with an r = 0.98. Nevertheless, the slope obtained was different for each one of them. The smallest concentration of inhibitor to achieve a 50% lysis inhibition of trophozoites was that of inhibitor III. In addition, it was demonstrated that the incubation of the trophozoites with this inhibitor increased the time needed to destroy CHO cells. We conclude that enzymatic inhibition of the PPi dependent phosphofructokinase caused by the PPi analogues was responsible for the modification of the lytic capacity of trophozoites, possibly by altering the metabolic pathway of carbohydrates.
Jiménez Cardoso
E
E
Laboratorio de Investigación en Parasitología, Hospital Infantil de México Federico Gómez, México D.F.
Cuevas Rosas
E
E
Jiménez Cardoso
J M
JM
Ortiz
B
B
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004164:Diphosphonates / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects; D004748:Entamoeba histolytica / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D012968:Etidronic Acid; D010274:Parasitology / Q000379:methods; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors*; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors*
D004164:Diphosphonates; D015800:Protozoan Proteins; C029285:hydroxymethanediphosphonic acid; C087308:1,1-hydroxyoctanodiphosphonate; D010732:Phosphofructokinase-1; D012968:Etidronic Acid
Disminución in vitro del efecto citolítico de E. histolytica por inhibición de su fosfofructocinasa.