title: A heterogeneous enzymatic assay for quantification of Plasmepsin II activity and the evaluation of its inhibitors.
abstract: The emergence and worldwide spreading of Plasmodium falciparum strains that shown to be resistant to traditional drugs is considered a very serious health problem, given the high mortality and morbidity rate of Malaria. In the search for new drugs against this parasite, Hb hydrolyzing enzymes, such as Plasmepsin II (Plm II), have been classified as very promising targets for therapeutic attacks. In this work, it is developed a cheap and high-throughput heterogeneous enzymatic assay for measuring Plasmepsin II activity in order to use it as a tool in the discovery of new inhibitors of this enzyme. In this assay, Plasmepsin II acts upon a solid-phase bound synthetic peptide (DU2) whose sequence comprises the cleavage site F(33)-L(34) present in Hb alpha-chain. The peptide surface density is quantified by means of a classical ELISA-based procedure. In order to estimate the kinetic constants of the system and to quantify both, enzymatic and inhibitory activity, it was used a model for the kinetics of enzyme quasi-saturable systems previously developed by our group, that fitted very well to the experimental data. It was used Pepstatin as a model inhibitor of Plasmepsin II and the resulting dose-response relation agreed with the expected behavior for the Pepstatin-Plasmepsin II pair under the employed experimental conditions.
authors.affiliation: Centro de Estudio de Proteínas, Facultad de Biología, Universidad de la Habana, Calle 25 # 455 Entre J e I, Vedado, CP 10400, Havana City, Cuba. esalas@fbio.uh.cu
authors.forename: Emir
authors.initials: E
authors.lastname: Salas
authors.forename: Angel
authors.initials: A
authors.lastname: Ramírez
authors.forename: Anabel
authors.initials: A
authors.lastname: Otero-Bilbao
authors.forename: Rayner
authors.initials: R
authors.lastname: Vázquez
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Reyes
authors.forename: Judith
authors.initials: J
authors.lastname: Mendiola
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Duarte
authors.forename: Anselmo
authors.initials: A
authors.lastname: Otero-González
authors.forename: Omar A
authors.initials: OA
authors.lastname: Gutiérrez
authors.forename: María A
authors.initials: MA
authors.lastname: Chávez
mesh_terms: D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D002384:Catalysis; D004796:Clinical Enzyme Tests / Q000191:economics / Q000379:methods*; D003462:Cuba; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005069:Evaluation Studies as Topic; D006454:Hemoglobins / Q000187:drug effects / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010436:Pepstatins / Q000494:pharmacology; D010446:Peptide Fragments / Q000138:chemical synthesis; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology; D011480:Protease Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D015800:Protozoan Proteins
chemical_list: D006454:Hemoglobins; D010436:Pepstatins; D010446:Peptide Fragments; D011480:Protease Inhibitors; D015800:Protozoan Proteins; D016282:Aspartic Acid Endopeptidases; C100637:plasmepsin II; C031375:pepstatin