The prtnonation constant values of tryptophan were studied at 25 C. different ionic strengths. 0.1-1.0 moldm", and various ionic media of NaCIO, and N4N01, using a combination of spectrophotometrie andpotentiometric techniques. The general vend for the two protonation con Slant Vai net of tryptophan is in theorder of NaC104 > NaNO3 in different ionic media. The dependence of protonation constan...

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...

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...

When a chromophore interacts with titrable molecular sites, the modeling of its photophysical properties requires to take into account all their possible protonation states. We have developed a multi-scale protocol, based on constant-pH molecular dynamics simulations coupled to QM/MM excitation energy calculations, aimed at sampling both the phase space and protonation state space of a short po...

The protonation constant values of salicylic and 5-nitrosalicylic acid werestudied by a combinationof spectrophotometric and potentiometric methods at 25 °C in wide range of ionic strength. The ionicstrength of solutions was kept constant by sodium perchlorate as background electrolyte at 0.10 to 3.0 moldm-3. Potentiometer was calibrated according to Gran method at each of ionic strength. The p...

In this research, the protonation constant value of tannic acid was determined at 25 °C and different ionic strengths (0.1 to 0.7 mol/dm3 NaCl) using potentiometric titration technique. The dependence of protonation constant on ionic strength was modeled and discussed by a Debye-Hückel type equation. Then, based on the obtained data from experiments, the minimizing Sum o...

the protonation constant values of salicylic and 5-nitrosalicylic acid werestudied by a combinationof spectrophotometric and potentiometric methods at 25 °c in wide range of ionic strength. the ionicstrength of solutions was kept constant by sodium perchlorate as background electrolyte at 0.10 to 3.0 moldm-3. potentiometer was calibrated according to gran method at each of ionic strength. the p...

The tandem Friedel-Crafts conjugate addition/asymmetric protonation reaction between 2-substituted indoles and methyl 2-acetamidoacrylate is reported. The reaction is catalyzed by (R)-3,3'-dibromo-BINOL in the presence of stoichiometric SnCl(4), and is the first example of a tandem conjugate addition/asymmetric protonation reaction using a BINOL·SnCl(4) complex as the catalyst. A range of indol...