Partial molar heat capacities and volumes of aqueous solutions of some peptides that model side-chains of proteins

Abstract

The partial molar volumes, V^∞₂, and partial molar heat capacities, C^∞_{p, 2}, at infinite dilution have been determined for the tripeptides glycyl-L-isoleucylglycine, glycyl-DL-threonylglycine, glycyl-L-asparagylglycine, glycyl-histidylglycine, glycylmethionylglycine and glycylphenylalanylglycine in aqueous solution at 25 °C. These results, in conjunction with those for glycylglycylglycine, were used to estimate the amino acid side-chain contributions to V^∞₂ and C^∞_{p, 2}. 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.