Tautomeric and microscopic protonation equilibria of some alpha-amino acids.

Dogan A., Kilic E.

Analytical biochemistry, cilt.365, sa.1, ss.7-13, 2007 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 365 Sayı: 1
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1016/j.ab.2007.02.019
  • Dergi Adı: Analytical biochemistry
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.7-13
  • Anahtar Kelimeler: amino acid, dipolar ion, microscopic/tautomeric protonation constants, solvent effect, potentiometry, DISSOCIATION-CONSTANTS, IONIZATION-CONSTANTS, SUBSTITUTED SALICYLIDENEANILINES, WATER, SOLVATION, SOLVENTS
  • Gazi Üniversitesi Adresli: Evet

Özet

The acid-base equilibria of several amino acids, namely glycine, L-alanine, L-valine, L-leucine, L-phenylalanine, L-serine, L-methionine, and L-isoleucine, have been characterized in terms of microscopic protonation constants and tautomeric ratios. In this study, the microscopic protonation constants and tautomeric ratios of eight amino acids in different ethanol-water mixtures have been determined. The variation of microscopic constants of amino acids is discussed on the basis of solute-solvent interactions, and the ratio of dipolar ionic form to neutral form is determined in ethanol-water mixtures (20/80% ethanol by volume). The dipolar ionic form still greatly predominates, even in 80% ethanol, as estimated from potentiometric titration data. (c) 2007 Elsevier Inc. All rights reserved.