Studies on the macroscopic protonation constants of some alpha-amino acids in ethanol-water mixtures.

Dogan A., Koseoglu F., Kilic E.

Analytical biochemistry, cilt.309, sa.1, ss.75-8, 2002 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 309 Sayı: 1
  • Basım Tarihi: 2002
  • Doi Numarası: 10.1016/s0003-2697(02)00254-3
  • Dergi Adı: Analytical biochemistry
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.75-8
  • Gazi Üniversitesi Adresli: Evet

Özet

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 25degreesC 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. (C) 2002 Elsevier Science (USA). All rights reserved.