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dc.contributor.authorBronckaers, A.
dc.contributor.authorAguado, L.
dc.contributor.authorNegri Martínez, Ana 
dc.contributor.authorCamarasa Rius, María José 
dc.contributor.authorBalzarini, Jan
dc.contributor.authorPérez Pérez, María Jesús
dc.contributor.authorGago Badenas, Federico 
dc.contributor.authorLiekens, S.
dc.date.accessioned2009-11-25T13:27:45Z
dc.date.available2009-11-25T13:27:45Z
dc.date.issued2009
dc.identifier.bibliographicCitationBiochemical Pharmacology 78 (2009) 231-240en_US
dc.identifier.urihttp://hdl.handle.net/10017/5046
dc.description.abstractThymidine phosphorylase (TP) is a catabolic enzyme in thymidine metabolism that is frequently upregulated in many solid tumors. Elevated TP levels are associated with tumor angiogenesis, metastasis and poor prognosis. Therefore, the use of TP inhibitors might offer a promising strategy for cancer treatment. The tritylated inosine derivative 5'-O-tritylinosine (previously designated KIN59) is a noncompetitive inhibitor of TP which was previously found to be instrumental for the crystallization of human TP. A combination of computational studies including normal mode analysis, automated ligand docking and molecular dynamics simulations were performed to define a plausible binding site for 5'-O-tritylinosine on human TP. A cavity in which 5'-O-tritylinosine could fit was identified in the vicinity of the Gly405-WI419 loop at a distance of about 11 angstrom from the substrate-binding site. In the X-ray crystal structure, this pocket is characterized by an intricate hydrogen-bonding network in which Asp203 was found to play an important role to afford the loop stabilization that is required for efficient enzyme catalysis. Site-directed mutagenesis of this amino acid residue afforded a mutant enzyme with a severely compromised catalytic efficiency (V-max /K-m of mutant enzyme similar to 50-fold lower than for wild-type TP) and pronounced resistance to the inhibitory effect of 5'-O-tritylinosine. In contrast, the D203A mutant enzyme kept full sensitivity to the competitive inhibitors 6-aminothymine and 6-amino-5-bromouracil, which is in line with the kinetic properties of these inhibitors. Our findings reveal the existence of a previously unrecognized site in TP that can be targeted by small molecules to inhibit the catalytic activity of TP. (C) 2009 Elsevier Inc. All rights reserved.en_US
dc.format.mimetypeapplication/pdfen
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.titleIdentification of aspartic acid-203 in human thymidine phosphorylase as an important residue for both catalysis and non-competitive inhibition by the small molecule "crystallization chaperone" 5'-O-tritylinosine (KIN59)en_US
dc.typeinfo:eu-repo/semantics/articleen
dc.subject.ecienciaCienciaes_ES
dc.subject.ecienciaFarmacologíaes_ES
dc.subject.ecienciaScienceen
dc.subject.ecienciaPharmacologyen
dc.contributor.affiliationUniversidad de Alcalá. Departamento de Farmacología
dc.relation.publisherversionhttp://dx.doi.org/10.1016/j.bcp.2009.04.011
dc.type.versioninfo:eu-repo/semantics/publishedVersionen_US
dc.identifier.doi10.1016/j.bcp.2009.04.011
dc.rights.accessRightsinfo:eu-repo/semantics/openAccessen


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