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Methods of quantum chemistry have been applied to double-charged complexes involving the transition metals Ni(2+), Cu(2+) and Zn(2+) with the aromatic amino acids (AAA) phenylalanine, tyrosine and tryptophan. The effect of hydration on the relative stability and geometry of the individual species studied has been evaluated within the supermolecule approach.(More)
The geometries and energies of factor Xa inhibitors edoxaban, eribaxaban, fidexaban, darexaban, letaxaban, and the dual factor Xa and thrombin inhibitors tanogitran and SAR107375 in both the gas-phase and aqueous solution were studied using the Becke3LYP/6-31++G(d,p) or Grimme's B97D/6-31++G(d,p) method. The fully optimized conformers of these(More)
Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor) and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p) level of(More)
Density functional theory methods with the B3LYP functional have been used to letter the acidity of car-boxyl, O-sulfo and N-sulfo groups in six basic monomeric structural units of heparin (The predicted gas-phase acidity of the acidic functional groups in the monomeric structural units of hep-arin is: O-sulfo > N-sulfo > carboxyl. The computed pK a values(More)
Quantum chemistry methods have been applied to charged complexes of the alkali metals Li+, Na+, and K+ with the aromatic amino acids (AAAs) phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp). The geometries of 72 different complexes (Phe·M, Tyr·M, Trp·M, M is Li+, Na+, or K+) were completely optimized at the B3LYP/6-311+G(d,p) level of density(More)
The IdoA2S structural unit of heparin (subunit G) may oscillate among the three conformations (4C1, 1C4, and 2So). Only the twisted boat conformation allowed the biologically active pentasaccharide unit of heparin (DEFGH) to bind to antithrombin. Our work reports, in detail, the results of systematic large-scale theoretical investigations of the three basic(More)
The molecular structure of four dimeric units (D-E, E-F, F-G, and G-H) of the DEFGH structural unit of heparin, their anionic forms, and their sodium salts have been studied using the B3LYP/6-31+G(d) method. The optimized geometries indicate that the most stable structure of these dimeric units in neutral state is stabilized via "bifurcated" sodium bonds.(More)
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