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

Volumetric Properties of Tripeptides with Polar Side-Chains: Partial Molar Volumes at (288.15 to 313.15) K and Partial Molar Expansions at 298.15 K of Some Peptides of Sequence Gly-X-Gly in Aqueous Solution

“…It is clear from these E °(R) results that the side-chain contributions to E 2 ° of a peptide derived using tripeptides as model compounds differ significantly from those based on the N -acetyl amino acid amides. These N -acetyl amino acid amides were shown in previous work to be a realistic set of model compounds that gave side-chain volumes that are in good agreement with those obtained using the tripeptides. In other words, the group contributions recommended for use in the additivity scheme to calculate partial molar volumes of polypeptides are not model dependent .…”

“…These E °(R) results are given in Table . Included in Table are the side-chain contributions derived using E 2 ° values reported , for some N -acetyl amino acid amides (AcXNH 2 ) and for N -acetylglycinamide (AcglyNH 2 ) . It is clear from these E °(R) results that the side-chain contributions to E 2 ° of a peptide derived using tripeptides as model compounds differ significantly from those based on the N -acetyl amino acid amides.…”

“… a E 2 ° values for AcXNH 2 were derived using V 2 ° ( T ) data from ref . b E 2 ° values for AcXNH 2 from ref . …”

Partial Molar Isentropic Compressions of Some Tetra- and Pentapeptides in Aqueous Solution: Implications for Group Additivity Schemes for Unfolded Proteins

“…These differences are considerably larger than those obtained using the gly-X-gly peptides as side-chain model compounds. Although AcXNH 2 compounds can be used successfully as side-chain models in group additivity schemes for the partial molar volumes and heat capacities of polypeptides [30,31], it is clear from the results presented in Table 5 that this is not the case for K • S,2 . The results of this study suggest that additivity schemes in which side-chains are modeled using the gly-X-gly tripeptides are more likely to achieve quantitative success in the prediction of K • S,2 for polypeptides and unfolded proteins than are those with K • S (R) values based on data for the AcXNH 2 compounds.…”

Partial Molar Heat Capacities at Chosen Temperatures in the Range (298.15 to 328.15) K and Partial Molar Volumes at 298.15 K of N-Acetyl-N′-methyl-l-α-amino Acid Amides in Aqueous Solution

“…In many research centers, studies have been carried out to determine the contributions of particular functional groups of the amino acid side chain of model molecules to thermodynamic parameters such as standard partial molar volume and standard partial molar heat capacity. , Based on the said chain contributions, some workers expected that it can be used to calculate C o p of protein in a hypothetical extended state in water . That is why it is important to determine the precise value of amino acid side chain contributions to examine properties like heat capacity or volume.…”