Characterisation of the antitrypanosomal activity of peptidyl α-aminoalkyl phosphonate diphenyl esters
Section snippets
Parasites and enzymes
T. b. brucei strain ILTat 1.1 was employed throughout. The history of this strain, originally isolated in Utembo, Kenya, is described in Ref. 17. Parasites were grown in adult male Wistar rats prior to passage in mice or were cultured as described previously [11]. For OP-Tb purification, parasites were purified from infected rat blood by a combination of Percoll® isopycnic gradient centrifugation [18] and anion-exchange chromatography on DEAE–cellulose [19]. OP-Tb was purified as described
Antitrypanosomal activity of peptidase inhibitors
A number of commercially available inhibitors of cysteine and serine peptidases were evaluated for activity against bloodstream-form T. b. brucei in a standard in vitro screen. With the exception of high molecular mass (protein) peptidase inhibitors, both classes of peptidase inhibitors were antitrypanosomal to varying degrees (Fig. 1). Of particular relevance to this study, three mechanism-based inhibitors of serine peptidases, without documented activity against cysteine peptidases, were
Discussion
The antitrypanosomal activity of cysteine peptidase inhibitors has been well documented in South American (for example, Ref. 15) and African (for example Ref. 16) trypanosomes. Indeed, the cysteine peptidase inhibitor E-64 exhibited antitrypanosomal activity in our in vitro screen (Fig. 1). Similarly, a number of thiol-reactive agents including iodoacetamide, iodoacetate, N-ethylmaleimide, and p-chloromercuribenzoate were potently antitrypanosomal. Although these compounds are inhibitors of
Acknowledgements
The study was supported by grants from the South African Foundation for Research Development and the University of Natal Research Fund. The authors wish to thank Lizette Moolman and Jonathan Edwards for assistance with experimental animals, and two anonymous reviewers for their comments. Rory E. Morty is a recipient of a Fellowship from the South African Foundation for Research Development.
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2012, Molecular and Biochemical ParasitologyCitation Excerpt :The T. b. brucei Lister 427 strain shows a preferential tropism for mouse testes [33] where parasites are not readily cleared by drugs after crossing microvascular endothelial cells into the interstitial tissue between the seminiferous tubules. Studies into the function of TbOPB during infection have so far been based on experiments using inhibitors, trypanocidal agents and neutralising antibodies [16,17,34–36]. To fully understand what role TbOPB plays in parasite physiology and host pathogenesis, oligopeptidase B null mutants (Δopb) were generated in the T. b. brucei Lister 427 strain and TbOPB was found not to be necessary for the survival of trypanosome parasites in vitro and during infection in mice.
Oligopeptidase B deficient mutants of Leishmania major
2011, Molecular and Biochemical ParasitologyCrystal structure of Leishmania major oligopeptidase B gives insight into the enzymatic properties of a trypanosomatid virulence factor
2010, Journal of Biological ChemistryCitation Excerpt :It is thought to degrade the regulatory peptide hormone, atrial natriuretic factor, reducing its levels (11, 15) and consequently affect the control of blood volume, leading to the circulatory system lesions observed in trypanosome infections (7). In these trypanosomes, OPB has been identified as a target of several drugs (pentamidine, diminazene, and suramin) (16) and irreversible inhibitors of the enzyme exhibit anti-trypanosomal activity in vitro and in vivo (14). Consequently, OPB is regarded as a potential target for the development of therapeutic drugs and an in-depth structural characterization of the enzyme is important in understanding its substrate specificity and as an aid to any prospective drug development process.
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Present address: Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Ave., New Haven, CT 06536, U.S.A.
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Present address: Department of Molecular Biology, Cambridge University, 80 Tennis Court Road, Cambridge, CB2 1QW, United Kingdom.
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Present address: Department of Chemical & Biochemical Engineering, Toyama University, Toyama 930, Japan.