title: Characterization and metal affinity of Tirofiban, a pharmaceutical compound used in acute coronary syndromes.
abstract: The crystal and molecular structure of Tirofiban [N-(n-butanesulfonyl)-O-(4-(4-piperidinyl)-butyl)-(S)-tyrosine] is here reported. In the solid state the carboxylic group is in the anionic form while the piperidine molecule appear in the protonated form. By H NMR spectroscopy and potentiometric study three pKa are found: pKa(COOH) = 3.1 (1), pKa(NHPIP) = 11.6(1) and pKa(NHSO2) = 13.8(1). The complexing ability of Tirofiban towards various metal ions (Cu(II), Ni(II), Co(II), Cd(II), Pb(II), Zn(II) and Ca(II)) is also determined by means of potentiometric studies. The prevailing species are [M(TirH)2]2+ where the ligand coordinates the metal ion through carboxylic group, while the piperidine nitrogen is still protonated. The great stability of these complexes may be due to the presence of hydrogen bond interactions, as well as the formation of stacking interactions involving the phenyl ring of the tyrosine residue.
authors.affiliation: Università degli Studi di Modena e Reggio Emilia, Dipartimento di Chimica, Via Campi, 183 41100 Modena, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Ferrari
authors.forename: L
authors.initials: L
authors.lastname: Menabue
authors.forename: M
authors.initials: M
authors.lastname: Saladini
mesh_terms: D003327:Coronary Disease / Q000188:drug therapy; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000378:metabolism*; D008958:Models, Molecular; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D011199:Potentiometry; D013055:Spectrophotometry, Infrared; D000077466:Tirofiban; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D008024:Ligands; D008670:Metals; D010975:Platelet Aggregation Inhibitors; D014443:Tyrosine; D000077466:Tirofiban