Thermodynamic Properties of Peptide Solutions. Part 17. Partial Molar Volumes and Heat Capacities of the Tripeptides GlyAspGly and GlyGluGly, and Their Salts K[GlyAspGly] and Na[GlyGluGly] in Aqueous Solution at 25 °C

Partial molar volumes and heat capacities of the N-acetyl amide derivatives of the amino acids asparagine, glutamine, tyrosine, and lysine monohydrochloride in aqueous solution at temperatures from T=288.15K to T=328.15K

“…method. This agreement suggests that maybe the peptide-based V (lysH + ) result at T = 298.15 K obtained using density data determined isothermally [11] is unreliable.…”

“…The values of V 2 ðHClÞ at the temperatures used in this work were those calculated using a polynomial in temperature that was derived [31] from an analysis of the most reliable V 2 ðT Þ data for HCl taken from the literature. The V (lysH + ) results calculated using equation (11), along with their estimated uncertainties, are given in table 7.…”

“…The V (R) results given in table 7 are compared in figure 3 with those calculated using V 2 data for tripeptides of sequence gly-X-gly and expressions analogous to equations (10) and (11). The solid curves given in the figure represent the side-chain volumes calculated from solution density data determined using a scanning densimetric method (d.s.d.)…”

“…The determination of various partial molar properties at infinite dilution for aqueous solutions of solutes that model specific structural features of globular proteins has been the focus of our research for many years [1][2][3][4][5][6][7][8][9][10][11]. The main objective of our recent work has been to establish reliable group additivity methods that can be used to calculate the partial molar heat capacities [8,9] and volumes [9,10] of completely unfolded, random coil, proteins in aqueous solution over a wide temperature range.…”

“…Partial molar volumes of the side-chains as a function of temperature: d, this work; h, V 2 data for the gly-X-gly tripeptides from[2,4,11]; --, V 2 data for the gly-X-gly tripeptides from[9,10], d.s.d. method.…”