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Fluorescent labels are often attachedto proteins to monitor binding and adsorption processes. Docking simulations for native henegg white lysozyme (HEWL) and HEWL labeled with fluorescein isothiocyanateshow that these adsorb differently on charged surfaces. Attachmentof even a small label can significantly change the interaction propertiesof a protein. Thus, the results of experiments with fluorescentlylabeled proteins should be interpreted by modeling the structuresand computing the interaction properties of both labeled and unlabeledspecies. [ABSTRACT FROM AUTHOR]

Enzyme kinetic parameters can differ between different species and isoenzymes for the same catalysed reaction. Computational approaches to calculate enzymatic kinetic parameters from the three-dimensional structures of proteins will be reviewed briefly here. Enzyme kinetic parameters may be derived by modelling and simulating the rate-determining process. An alternative, approximate, but more computationally efficient approach is the comparison of molecular interaction fields for experimentally characterized enzymes and those for which parameters should be determined. A correlation between differences in interaction fields and experimentally determined kinetic parameters can be used to determine parameters for orthologous enzymes from other species. The estimation of enzymatic kinetic parameters is an important step in setting up mathematical models of biochemical pathways in systems biology. [ABSTRACT FROM AUTHOR]

Folate analogue inhibitors of Leishmania majorpteridine reductase (PTR1) are potential antiparasitic drug candidates for combined therapy with dihydrofolate reductase (DHFR) inhibitors. To identify new molecules with specificity for PTR1, we carried out a virtual screening of the Available Chemicals Directory (ACD) database to select compounds that could interact with L. majorPTR1 but not with human DHFR. Through two rounds of drug discovery, we successfully identified eighteen drug-like molecules with low micromolar affinities and high in vitro specificity profiles. Their efficacy against Leishmaniaspecies was studied in cultured cells of the promastigote stage, using the compounds both alone and in combination with 1(pyrimethamine; 5-(4-chlorophenyl)-6-ethylpyrimidine-2,4-diamine). Six compounds showed efficacy only in combination. In toxicity tests against human fibroblasts, several compounds showed low toxicity. One compound, 5c(riluzole; 6-(trifluoromethoxy)-1,3-benzothiazol-2-ylamine), a known drug approved for CNS pathologies, was active in combination and is suitable for early preclinical evaluation of its potential for label extension as a PTR1 inhibitor and antiparasitic drug candidate. [ABSTRACT FROM AUTHOR]