Partial molar volumes of the amino acid side-chains of proteins in aqueous solution: some comments on their estimation using partial molar volumes of amino acids and small peptides.

The partial molar volumes of some amino acid side-chains were determined in two recent studies [Makhatadze, G.I., et al. (1990) Biopolymers 30, 1001, and Reading, J.F. & Hedwig, G.R. (1990) J. Chem. Soc. Faraday Trans. 86, 3117] using partial molar volume data, V02, in aqueous solution at 25 degrees C for some peptides of sequence Gly-X-Gly, where X is an amino acid. These side-chain partial molar volumes are critically compared with those obtained using V02 data for amino acids. It is concluded that side-chain partial molar volumes calculated using V02 data for the tripeptides are better estimates of side-chain partial molar volumes in proteins than are those determined using V02 data for amino acids.