Back to Search
Start Over
Bisphosphonates as inhibitors of Trypanosoma cruzi hexokinase: kinetic and metabolic studies.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2007 Apr 27; Vol. 282 (17), pp. 12377-87. Date of Electronic Publication: 2007 Feb 28. - Publication Year :
- 2007
-
Abstract
- Trypanosoma cruzi, the etiologic agent of Chagas disease, has an unusual ATP-dependent hexokinase (TcHK) that is not affected by D-glucose 6-phosphate, but is non-competitively inhibited by inorganic pyrophosphate (PP(i)), suggesting a heterotropic modulator effect. In a previous study we identified a novel family of bisphosphonates, metabolically stable analogs of PP(i), which are potent and selective inhibitors of TcHK as well as the proliferation of the clinically relevant intracellular amastigote form of the parasite in vitro (Hudock, M. P., Sanz-Rodriguez, C. E., Song, Y., Chan, J. M., Zhang, Y., Odeh, S., Kosztowski, T., Leon-Rossell, A., Concepcion, J. L., Yardley, V., Croft, S. L., Urbina, J. A., and Oldfield, E. (2006) J. Med. Chem. 49, 215-223). In this work, we report a detailed kinetic analysis of the effects of three of these bisphosphonates on homogeneous TcHK, as well as on the enzyme in purified intact glycosomes, peroxisome-like organelles that contain most of the glycolytic pathway enzymes in this organism. We also investigated the effects of the same compounds on glucose consumption by intact and digitonin-permeabilized T. cruzi epimastigotes, and on the growth of such cells in liver-infusion tryptose medium. The bisphosphonates investigated were several orders of magnitude more active than PP(i) as non-competitive or mixed inhibitors of TcHK and blocked the use of glucose by the epimastigotes, inducing a metabolic shift toward the use of amino acids as carbon and energy sources. Furthermore, there was a significant correlation between the IC(50) values for TcHK inhibition and those for epimastigote growth inhibition for the 12 most potent compounds of this series. Finally, these bisphosphonates did not affect the sterol composition of the treated cells, indicating that they do not act as inhibitors of farnesyl diphosphate synthase. Taken together, our results suggest that these novel bisphosphonates act primarily as specific inhibitors of TcHK and may represent a novel class of selective anti-T. cruzi agents.
- Subjects :
- Animals
Chagas Disease drug therapy
Chagas Disease enzymology
Diphosphates metabolism
Diphosphonates therapeutic use
Enzyme Inhibitors therapeutic use
Geranyltranstransferase metabolism
Glucose-6-Phosphate metabolism
Hexokinase metabolism
Humans
Kinetics
Organelles enzymology
Protozoan Proteins metabolism
Sterols metabolism
Trypanosoma cruzi growth & development
Diphosphonates pharmacology
Enzyme Inhibitors pharmacology
Hexokinase antagonists & inhibitors
Protozoan Proteins antagonists & inhibitors
Trypanosoma cruzi enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 282
- Issue :
- 17
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 17329254
- Full Text :
- https://doi.org/10.1074/jbc.M607286200