The ingenious combination of lactate and diethylenetriamine-N,N,N’,N”,N”pentaacetic acid (DTPA) as an aqueous actinide-complexing medium forms the basis of the successful separation of americium and curium from lanthanides known as the TALSPEAK process. While numerous reports in the prior literature have focused on the optimization of this solvent extraction system, considerably less attention ...

A chemical model of the acid-base properties is optimized for each white wine under study, together with the calculation of their ionic strength, taking into account the contributions of all significant ionic species (strong electrolytes and weak one sensitive to the chemical equilibria). Coupling the HPLC-IEC and HPLC-RP methods, we are able to quantify up to 12 carboxylic acids, the most rele...

When individual titratable sites in a molecule interact with each other, their pH titration can be considerably more complex than that of an independent site described by the classical Henderson-Hasselbalch equation. We propose a novel framework that decomposes any complex titration behavior into simple standard components. The approach maps the set of N interacting sites in the molecule onto a...

The protonation of the ligand molecule and the protein binding site has a significant influence on the results obtained by protein-ligand docking. Due to the inability of X-ray crystallography to resolve the hydrogen atom in protein and protein complex structures, the correct protonation for the protein and the ligand has to be assigned on a theoretical basis before the structures can be used. ...

The photo-oxidation of purine nucleotides adenosine-5'-monophosphate (AMP) and guanosine-5'-monophosphate (GMP) by 3,3',4,4'-benzophenone tetracarboxylic acid (TCBP) has been investigated in aqueous solutions using nanosecond laser flash photolysis (LFP) and time-resolved chemically induced dynamic nuclear polarization (CIDNP). The pH dependences of quenching rate constants and of geminate pola...

We studied the irreversible thermal denaturation of chymopapain, a papain-related cysteine proteinase. It was found that this process follows simple first-order kinetics under all conditions tested. Rate constants determined by monitoring ellipticity changes at 220 or 279 nm are essentially identical, indicating that denaturation involves global unfolding of the protein. Enthalpies (DeltaH(doub...

To determine the effect of the redox state of the Rieske protein on ligand binding to the quinol oxidation site of the bc(1) complex, we measured the binding rate constants (k(1)) for stigmatellin and myxothiazol, at different concentrations of decylbenzoquinone or decylbenzoquinol, in the bovine bc(1) complex with the Rieske protein in the oxidized or reduced state. Stigmatellin and myxothiazo...

The electric field gradient (EFG) has been calculated in zeolite clusters at the aluminium site surrounded by four SiO4 tetrahedra. Density functional theory (DFT) with the 6-31G** basis set has been employed. Formation of a Brønsted acid site by protonation of one oxygen atom of the AlO4 tetrahedron perturbs the coordination of aluminium, i.e., the corresponding Al-O bond is considerably weake...