title: Quantitative assessment of the glyoxalase pathway in Leishmania infantum as a therapeutic target by modelling and computer simulation.
abstract: The glyoxalase pathway of Leishmania infantum was kinetically characterized as a trypanothione-dependent system. Using time course analysis based on parameter fitting with a genetic algorithm, kinetic parameters were estimated for both enzymes, with trypanothione derived substrates. A K(m) of 0.253 mm and a V of 0.21 micromol.min(-1).mg(-1)for glyoxalase I, and a K(m) of 0.098 mm and a V of 0.18 micromol.min(-1).mg(-1) for glyoxalase II, were obtained. Modelling and computer simulation were used for evaluating the relevance of the glyoxalase pathway as a potential therapeutic target by revealing the importance of critical parameters of this pathway in Leishmania infantum. A sensitivity analysis of the pathway was performed using experimentally validated kinetic models and experimentally determined metabolite concentrations and kinetic parameters. The measurement of metabolites in L. infantum involved the identification and quantification of methylglyoxal and intracellular thiols. Methylglyoxal formation in L. infantum is nonenzymatic. The sensitivity analysis revealed that the most critical parameters for controlling the intracellular concentration of methylglyoxal are its formation rate and the concentration of trypanothione. Glyoxalase I and II activities play only a minor role in maintaining a low intracellular methylglyoxal concentration. The importance of the glyoxalase pathway as a therapeutic target is very small, compared to the much greater effects caused by decreasing trypanothione concentration or increasing methylglyoxal concentration.
authors.affiliation: Centro de Química e Bioquímica, Departmento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Portugal.
authors.forename: Marta
authors.initials: M
authors.lastname: Sousa Silva
authors.forename: António E N
authors.initials: AE
authors.lastname: Ferreira
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Tomás
authors.forename: Carlos
authors.initials: C
authors.lastname: Cordeiro
authors.forename: Ana
authors.initials: A
authors.lastname: Ponces Freire
mesh_terms: D000818:Animals; D003198:Computer Simulation; D007791:Lactoylglutathione Lyase / Q000378:metabolism*; D018314:Leishmania infantum / Q000201:enzymology*; D007896:Leishmaniasis / Q000188:drug therapy; D008433:Mathematics; D008954:Models, Biological; D015394:Molecular Structure; D015800:Protozoan Proteins / Q000378:metabolism; D011765:Pyruvaldehyde / Q000737:chemistry / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000378:metabolism*; D000099301:Hydroxyacylglutathione Hydrolase
chemical_list: D007791:Lactoylglutathione Lyase; D015800:Protozoan Proteins; D011765:Pyruvaldehyde; D013438:Sulfhydryl Compounds; D013869:Thiolester Hydrolases; D000099301:Hydroxyacylglutathione Hydrolase