title: Insights into the Interactions of Fasciola hepatica Cathepsin L3 with a Substrate and Potential Novel Inhibitors through In Silico Approaches.
abstract: BACKGROUND
  Fasciola hepatica is the causative agent of fascioliasis, a disease affecting grazing animals, causing economic losses in global agriculture and currently being an important human zoonosis. Overuse of chemotherapeutics against fascioliasis has increased the populations of drug resistant parasites. F. hepatica cathepsin L3 is a protease that plays important roles during the life cycle of fluke. Due to its particular collagenolytic activity it is considered an attractive target against the infective phase of F. hepatica.
  
  
  RESULTS
  Starting with a three dimensional model of FhCL3 we performed a structure-based design of novel inhibitors through a computational study that combined virtual screening, molecular dynamics simulations, and binding free energy (ΔGbind) calculations. Virtual screening was carried out by docking inhibitors obtained from the MYBRIDGE-HitFinder database inside FhCL3 and human cathepsin L substrate-binding sites. On the basis of dock-scores, five compounds were predicted as selective inhibitors of FhCL3. Molecular dynamic simulations were performed and, subsequently, an end-point method was employed to predict ΔGbind values. Two compounds with the best ΔGbind values (-10.68 kcal/mol and -7.16 kcal/mol), comparable to that of the positive control (-10.55 kcal/mol), were identified. A similar approach was followed to structurally and energetically characterize the interface of FhCL3 in complex with a peptidic substrate. Finally, through pair-wise and per-residue free energy decomposition we identified residues that are critical for the substrate/ligand binding and for the enzyme specificity.
  
  
  CONCLUSIONS
  The present study is the first computer-aided drug design approach against F. hepatica cathepsins. Here we predict the principal determinants of binding of FhCL3 in complex with a natural substrate by detailed energetic characterization of protease interaction surface. We also propose novel compounds as FhCL3 inhibitors. Overall, these results will foster the future rational design of new inhibitors against FhCL3, as well as other F. hepatica cathepsins.
authors.affiliation: Departamento de Biología Molecular, Centro Nacional de Sanidad Agropecuaria de Cuba (CENSA), San José de las Lajas, Mayabeque, Cuba.
authors.forename: Lilian
authors.initials: L
authors.lastname: Hernández Alvarez
authors.affiliation: Departamento de Biología Molecular, Centro Nacional de Sanidad Agropecuaria de Cuba (CENSA), San José de las Lajas, Mayabeque, Cuba.
authors.forename: Dany
authors.initials: D
authors.lastname: Naranjo Feliciano
authors.affiliation: Centro de Estudios de Proteínas (CEP), Facultad de Biología, Universidad de la Habana, La Habana, Cuba.
authors.forename: Jorge Enrique
authors.initials: JE
authors.lastname: Hernández González
authors.forename: R O
authors.initials: RO
authors.lastname: Soares
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil; Diretoria de Metrologia Aplicada às Ciências da Vida (DIMAV), Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Rio de Janeiro, Brazil.
authors.forename: Rosemberg de Oliveira
authors.initials: Rde O
authors.lastname: Soares
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil; Diretoria de Metrologia Aplicada às Ciências da Vida (DIMAV), Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Rio de Janeiro, Brazil.
authors.forename: Diego Enry
authors.initials: DE
authors.lastname: Barreto Gomes
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.
authors.forename: Pedro Geraldo
authors.initials: PG
authors.lastname: Pascutti
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D056668:Cathepsin L / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017076:Computer-Aided Design; D055808:Drug Discovery / Q000379:methods*; D005210:Fasciola hepatica / Q000187:drug effects* / Q000201:enzymology; D005211:Fascioliasis / Q000175:diagnosis / Q000188:drug therapy / Q000469:parasitology; D006801:Humans; D008018:Life Cycle Stages; D056004:Molecular Dynamics Simulation; D021261:Parasitic Sensitivity Tests; D015047:Zoonoses / Q000188:drug therapy / Q000469:parasitology
chemical_list: D056668:Cathepsin L