| Abstract: | The densities at 298.15 K of aqueous solutions containing some terminally substituted amino acids and peptides containing the glycyl, L -and D -alanyl, L -leucyl, sarcosyl, and L -prolyl residues have been dertermined and standard state partial molar volumes and volumetric pairwise virial coefficients obtained. It is shown that the partial molar volumes can be represented using group volume contributions, but this approach is only approximate, and significant effects of N-terminal substitution and sequence dependence are observed. The volumetric virial coefficients for the amino acid amides have been expressed using a group-additivity approach, and the results obtained indicate that the dominant contributions come from peptide group interactions with other peptide groups and with hydrophobic groups. There is also some evidence of both sequence and chiral effects on the volumetric virial coefficients for proline-containing dipeptides. |
