Reactivation of diethyl p-nitrophenyl phosphate inhibited human serum cholinesterase by pyridine-Z-aldoxime methiodide and isonitrosoacetophenone has been investigated as a function of reactivator concentration, pH, and temperature in boric acid-borax buffer and in salt solution. Constants shown were the dissociation constants of the diethylphosphoryl cholinesterase reactivator complex for the ...

Stepwise formation constants of folic acid, N[p[ [ (2-amino-4-hydroxy-6-pteridyl) methyl] ami­ no] benzyl] glutamic acid, with the carcinogenic metal ions, aluminium (III) , chromium (III) , beryl­ lium (II) , lead (II) and uranium (VI) have been determined at 30 °C, and at various ionic strengths, viz. 0.01 m, 0.05 M, 0.10 m, maintained by potassium nitrate solution. The formation of the chela...

The acid-base chemistry of a tetraprotic, ampholyte ACE inhibitor, lisinopril, was studied by different methods. Potentiometry in aqueous medium and a co-solvent technique in methanol-water mixtures as well as 1 H NMR-pH titration were applied for the highly precise measurement of protonation macroconstants. The log K values of lisinopril (at 25.0°C and 0.15 M ionic strength) were found: log K1...

The acid dissociation constants of long-chain esters of carnitine (5-hydroxy-~,trimethylammonium-butyrate) above the critical micelle concentration were determined potentiometrieally at several concentrations of added KC1. As the degree of protonation 5 increases the apparent pK values decrease owing to the increased positive charge on the micelle. The difference in pK between the neutral (zwit...

A series of charge ladders of bovine carbonic anhydrase II were synthesized and the relative abundances of the rungs analyzed by capillary electrophoresis as a function of the quantity of acylating agent used. A simulation that models the kinetics of formation of the members of the charge ladders is described. The observed rate constants decreased as the extent of acylation increased. These rat...

Central to Alzheimer's disease (AD) is the assembly of amyloid-beta peptide (Aβ) into fibrils. A reduction in pH accompanying inflammation or subcellular compartments, may accelerate fibril formation as approaches Aβ’s isoelectric point (pI). Using global fitting kinetics over a range pHs, we identify impact net charge has on individual microscopic rate constants. We show that primary nucleatio...

New potentiometric experiments have been performed in NaCl and in (CH3)4NCl media, to determine the protonation constants, the protonation enthalpy changes and the solubility of six natural α-amino acids, namely Glycine (Gly), Alanine (Ala), Valine (Val), Leucine (Leu), Serine (Ser) and Phenylalanine (Phe). The aim of the work is the rationalization of the protonation thermodynamics (log [Formu...

Equilibrium constants of Cadmium Oxide (CdO) nanoparticles complexes in human cancer cells with DNA/RNA ligands have been studied with biospectroscopic methods such as 1HNMR, 13CNMR, 31PNMR, Attenuated Total Reflectance Fourier Transform Infrared (ATR–FTIR) and FT–Raman spectroscopies in cosolvent systems at 10, 20, 30°C ± 0.5 and 1 mol.dm–3 ionic strength, was maintained using Sodium Chloride ...

Three new Schiff bases derived from the condensation reaction of thiophene-2-carbaldehyde and DL-alanine, DL-valine and DL-phenylalanine have been synthesized and their Co(II), Ni(II) and Cu(II) complexes have been prepared. The Schiff bases and the complexes have been characterized by their analytical and spectral data. The protonation constants of the Schiff bases and stability constants of t...

Surfactant molecules are used as interesting tools to study the structure, function and stability of proteins. Protonation states of amino acids may be changed in the presence of surfactants. In this work, using experimental observations and molecular dynamic simulation, the effects of sodium dodecyl sulfate on the acid dissociation constants of tryptophan was examined. The acid–base equilibriu...