THERMODYNAMIC PROPERTIES OF PEPTIDE SOLUTIONS .10. PARTIAL MOLAR HEAT-CAPACITIES AND VOLUMES OF AQUEOUS-SOLUTIONS OF SOME PEPTIDES THAT MODEL SIDE-CHAINS OF PROTEINS

The partial molar volumes, V-2(infinity) and partial molar heat capacities, C-p(infinity), C-2(infinity), at infinite dilution have been determined for the tripeptides glycyl-L-isoleucylglycine, glycyl-DL-threonylglycine, glycyl-L-asparagylglycine, glycylhistidylglycine, glycylmethionylglycine and glycylphenylalanylglycine in aqueous solution at 25-degrees-C. These results, in conjunction with those for glycylglycylglycine, were used to estimate the amino acid side-chain contributions to V-2(infinity) and C-p(infinity), C-2(infinity). The side-chain contributions are compared with those determined using other model compounds. For some side-chains the heat capacities were found to correlate well with the side-chain non-polar surface areas.