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 [Makhatadzes, 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, V   2 0 , in aqueous solution at 25°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 V   2 0data for amino acids. It is concluded that side‐chain partial molar volumes calculated using V   2 0data for the tripeptides are better estimates of side‐chain partial molar volumes in proteins than are those determined using V   2 0data for amino acids.