Studies on the macroscopic protonation constants of some alpha-amino acids in ethanol-water mixtures |
| |
Authors: | Dogan Alev Köseoglu Fitnat Kiliç Esma |
| |
Affiliation: | Department of Chemistry, Faculty of Gazi Education, University of Gazi, Ankara, Turkey. adogan@gef.gazi.edu.tr |
| |
Abstract: | Both to demonstrate whether the predominant species are dipolar ion or the neutral form and to predict the change of dipolar form to neutral form ratio in ethanol-water mixtures, the macroscopic protonation constants of eight alpha-amino acid (glycine, L-alanine, L-valine, L-leucine, L-phenylalanine, L-serine, L-methionine, and L-isoleucine) were determined potentiometrically in 20-80% (v/v) ethanol-water mixtures at 25 degrees C with an ionic strength of 0.10 M. The calculation of the constants was carried out using a PKAS computer program. The effect of solvent composition on the protonation constants and the dipolar ionic to neutral form ratio of these acids in the mixed solvents are discussed. One can conclude that the dipolar form of amino acids, HA(+/-), dominates in ethanol-water mixtures. |
| |
Keywords: | α-Amino acid Ethanol-water mixture Potentiometry Macroscopic protonation constants Solvent effect |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|