title: Kinetics and docking studies of two potential new inhibitors of the nucleoside hydrolase from Leishmania donovani.
abstract: In this study the recombinant enzyme nucleoside hydrolase of Leishmania donovani (rLdNH) was expressed in Escherichia coli in connection with maltose binding protein (MBP). The rLdNH-MBP showed efficient a significant in vitro activity with inosine as substrate. From the coupled reaction with xanthine oxidase (XO) it was possible to determine the kinetic constants of rLdNH-MBP as K(M) (434 ± 109 μM) and V(max) (0.20 ± 0.02 μM). In addition, two nucleoside analogs (compounds 1 and 2) were tested as prototypes of rLdNH inhibitors. These compounds presented high affinity for the enzyme with K(i) values of 1.6 ± 0.2 and 17.0 ± 2.1 μM, respectively, as well as 271 and 26 folds higher than the affinity constant found for inosine. We also determined the type of enzyme inhibition, using double-reciprocal plot for these two compounds and the results confirmed a competitive inhibition. Additional docking studies showed the binding manner of compounds 1 and 2 inside the active site of LdNH revealing the essential residues for an effective inhibition. These results confirm that compounds 1 and 2 are strong rLdNH-MBP inhibitors.
authors.affiliation: Departamento de Química, Instituto Militar de Engenharia, Praça General Tibúrcio 80, 22290-270 Rio de Janeiro, RJ, Brazil.
authors.forename: Magdalena Nascimento
authors.initials: MN
authors.lastname: Rennó
authors.forename: Tanos Celmar Costa
authors.initials: TC
authors.lastname: França
authors.forename: Dirlei
authors.initials: D
authors.lastname: Nico
authors.forename: Clarisa B
authors.initials: CB
authors.lastname: Palatnik-de-Sousa
authors.forename: Luzineide Wanderley
authors.initials: LW
authors.lastname: Tinoco
authors.forename: José Daniel
authors.initials: JD
authors.lastname: Figueroa-Villar
mesh_terms: D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D007700:Kinetics; D007893:Leishmania donovani / Q000201:enzymology*; D058619:Maltose-Binding Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D009699:N-Glycosyl Hydrolases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism; D009705:Nucleosides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D058619:Maltose-Binding Proteins; D009705:Nucleosides; D011994:Recombinant Proteins; D009699:N-Glycosyl Hydrolases