Thermodynamic Studies of Trans-4-Hydroxy-L-Proline at Different Ionic Medium, Ionic Strength and Temperature

Determine the solubility as well as the acidic constants of trans-4-hydroxy-L-proline in 0.16 and 3.5 Mol.kg-1 NaClO4 and in 0.16 and 3.18 Mol.kg-1 NaCl at two different temperature, i.e. 298.15 and 310.15 K. trans-4-Hydroxy-L-proline, HL, is one of the most abundant amino acids present in collagen. As a major part of this protein, the measurement of hydroxyproline levels can be used as an indicator of collagen content. The protonation constants of ligand, K1 and K2, combined with the salting effects on the ligand in the ionic media were treated by the specific ion interaction theory, SIT, to give equilibrium constants at the infinite dilution reference state at 298.15 K and at 310.15 K, as well as specific interaction coefficients of the cation and anion of trans-4-hydroxy-L-proline with the media ions at the standard temperature, i.e. 298.15 K.