title: Kinetics and mechanistic study of competitive inhibition of thymidine phosphorylase by 5-fluoruracil derivatives.
abstract: In a previous investigation, cationic liposomes formulated with new 5-FU derivatives, differing for the length of the polyoxyethylenic spacer that links the N(3) position of 5-FU to an alkyl chain of 12 carbon atoms, showed a higher cytotoxicity compared to free 5-FU, the cytotoxic effect being directly related to the length of the spacer. To better understand the correlation of the spacer length with toxicity, we carried out initial rate studies to determine inhibition, equilibrium and kinetic constants (KI, KM, kcat), and get inside inhibition activity of the 5-FU derivatives and their mechanism of action, a crucial information to design structural variations for improving the anticancer activity. The experimental investigation was supported by docking simulations based on the X-ray structure of thymidine phosphorylase (TP) from Escherichia coli complexed with 3'-azido-2'-fluoro-dideoxyuridin. Theoretical and experimental results showed that all the derivatives exert the same inhibition activity of 5-FU either as monomer and when embedded in lipid bilayer.
authors.affiliation: Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell'Aquila, Via Vetoio, 67100 Coppito (Aq), Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Petaccia
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Gentili
authors.affiliation: CINECA, SCAI-Super Computing Applications and Innovation Department, Via dei Tizii, 6, 00185 Rome, Italy.
authors.forename: Neva
authors.initials: N
authors.lastname: Bešker
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: D'Abramo
authors.affiliation: Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell'Aquila, Via Vetoio, 67100 Coppito (Aq), Italy. Electronic address: luisa.giansanti@univaq.it.
authors.forename: Luisa
authors.initials: L
authors.lastname: Giansanti
authors.affiliation: Dipartimento di Biologia Ambientale, Università degli Studi di Roma "La Sapienza", P.le Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Leonelli
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: La Bella
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Denise
authors.initials: D
authors.lastname: Gradella Villalva
authors.affiliation: CNR-Istituto di Metodologie Chimiche, Via Salaria km 29.300, Monterotondo Scalo, 00016 Rome, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Mancini
mesh_terms: D000963:Antimetabolites / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D001667:Binding, Competitive; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D005472:Fluorouracil / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D062105:Molecular Docking Simulation; D015394:Molecular Structure; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013936:Thymidine / Q000737:chemistry / Q000378:metabolism*; D013939:Thymidine Phosphorylase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000963:Antimetabolites; D029968:Escherichia coli Proteins; D008081:Liposomes; D013939:Thymidine Phosphorylase; D005472:Fluorouracil; D004134:Dimyristoylphosphatidylcholine; D013936:Thymidine
keywords: 5-Fluorouracil; Enzymatic inhibition; Liposomes; Polyoxyethylenic spacer