The Microscopic and Tautomeric Protonation Constants of Some α-Amino Acids in Dioxane–Water Mixtures

Temperature dependence studies and microscopic protonation constants of L-alanine and β-alanine in acetonitrile – water mixtures

“…Nevertheless, recent works argue that solvents-water mixtures is fairly suitable [2,17]. Nonaqueous media and water -solvent mixtures are recommended because of express better model for in vivo reactions [8]. Generally, only water and methanol, ethanol, dioxane, acetonitrile and tetrahydrofuran-water mixtures have examined [2,5,8,10,13,17,18].…”

“…Nonaqueous media and water -solvent mixtures are recommended because of express better model for in vivo reactions [8]. Generally, only water and methanol, ethanol, dioxane, acetonitrile and tetrahydrofuran-water mixtures have examined [2,5,8,10,13,17,18]. We intend to contribute to the literature with an acetonitrile-water mixture that has been underutilized.…”

“…Amino acids methyl esters have alkylated cite and according to literature, amino acids methyl esters pka values assumed to be equal pk21 values because of the alkylated cite of the molecule has relatively same influence on molecule [2,3,8,9]. Micro protonation constants pk11, pk12, and pk22 values are calculated with potentiometrically observed macro protonation constants with and below mentioned expressions:…”

“…β-alanine is a non-proteinogenic amino acid and have role in carnosine metabolism [7]. Amino acids' zwitterionic structure reveal macroscopic (K1, K2) and microscopic (k11, k12, k21, k22) constants as acid-base interactions [8,9]. Macroscopic and microscopic protonation constants of amino acids have fundamental importance; besides they are beneficial to explain the biological activity of proteins as a function of pH [2,10,11].…”

“…Macroscopic and microscopic protonation constants of amino acids have fundamental importance; besides they are beneficial to explain the biological activity of proteins as a function of pH [2,10,11]. In individual pH, protonated and unprotonated forms of molecules determined microscopic protonation constant values are useful for calculating the pH-dependent distribution of forms and demonstrating and understanding communication between the extracellular and intracellular media in numberless biological systems [8,12]. Thermodynamic descriptions including enthalpic and entropic contributions of systems reveal us compounds physicochemical parameters such as solubility, stability, or ionization at various temperatures [13][14][15][16].…”