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Protonation equilibria of biologically active ligands in mixed aqueous organic solvents.

El-Sherif AA, Shoukry MM, Abd Elkarim AT, Barakat MH - Bioinorg Chem Appl (2014)

Bottom Line: The review is mainly concerned with the protonation equilibria of biologically active ligands like amino acids, peptides, DNA constituents, and amino acid esters in nonaqueous media.Equilibrium concentrations of proton-ligand formation as a function of pH were investigated.Also, thermodynamics associated with protonation equilibria were also discussed.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt ; Department of Chemistry, Faculty of Arts and Science, Northern Border University, Rafha, Saudi Arabia.

ABSTRACT
The review is mainly concerned with the protonation equilibria of biologically active ligands like amino acids, peptides, DNA constituents, and amino acid esters in nonaqueous media. Equilibrium concentrations of proton-ligand formation as a function of pH were investigated. Also, thermodynamics associated with protonation equilibria were also discussed.

No MeSH data available.


The variation of protonation constants of glycine with the percentage of DMSO.
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fig12: The variation of protonation constants of glycine with the percentage of DMSO.

Mentions: The stoichiometric protonation constants of glycine, L-alanine, L-phenylalanine, L-threonine, and L-methionine in water-DMSO mixtures are given in Table 11. The protonation constants K1 and K2 are related to the protonation of the amino nitrogen and the carboxyl oxygen, respectively. When the change of log⁡10⁡K1 with the solvent composition, given in Table 11, is examined for α-amino acids, it is observed that these values increase with an increasing percent of dimethyl sulfoxide. The linear relation is given in Figure 12, for glycine as a representative example of α-amino acids. This can be explained by structural changes in the amino acids as the medium becomes more like dimethyl sulfoxide. The neutral form of the amino acids (HL) is subjected to a larger amount of solvation, compared to the anionic form (L−) in dimethyl sulfoxide rich media. In water-rich media, however, the reverse will be the case.


Protonation equilibria of biologically active ligands in mixed aqueous organic solvents.

El-Sherif AA, Shoukry MM, Abd Elkarim AT, Barakat MH - Bioinorg Chem Appl (2014)

The variation of protonation constants of glycine with the percentage of DMSO.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150405&req=5

fig12: The variation of protonation constants of glycine with the percentage of DMSO.
Mentions: The stoichiometric protonation constants of glycine, L-alanine, L-phenylalanine, L-threonine, and L-methionine in water-DMSO mixtures are given in Table 11. The protonation constants K1 and K2 are related to the protonation of the amino nitrogen and the carboxyl oxygen, respectively. When the change of log⁡10⁡K1 with the solvent composition, given in Table 11, is examined for α-amino acids, it is observed that these values increase with an increasing percent of dimethyl sulfoxide. The linear relation is given in Figure 12, for glycine as a representative example of α-amino acids. This can be explained by structural changes in the amino acids as the medium becomes more like dimethyl sulfoxide. The neutral form of the amino acids (HL) is subjected to a larger amount of solvation, compared to the anionic form (L−) in dimethyl sulfoxide rich media. In water-rich media, however, the reverse will be the case.

Bottom Line: The review is mainly concerned with the protonation equilibria of biologically active ligands like amino acids, peptides, DNA constituents, and amino acid esters in nonaqueous media.Equilibrium concentrations of proton-ligand formation as a function of pH were investigated.Also, thermodynamics associated with protonation equilibria were also discussed.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt ; Department of Chemistry, Faculty of Arts and Science, Northern Border University, Rafha, Saudi Arabia.

ABSTRACT
The review is mainly concerned with the protonation equilibria of biologically active ligands like amino acids, peptides, DNA constituents, and amino acid esters in nonaqueous media. Equilibrium concentrations of proton-ligand formation as a function of pH were investigated. Also, thermodynamics associated with protonation equilibria were also discussed.

No MeSH data available.