Partial molar volumes of proteins: amino acid side-chain contributions derived from the partial molar volumes of some tripeptides over the temperature range 10-90 degrees C

The partial molar volumes of tripeptides of sequence glycyl-X-glycine, wher e X is one of the amino acids alanine, leucine, threonine, glutamine, pheny lalanine, histidine, cysteine, proline, glutamic acid, and arginine, have b een determined in aqueous solution over the temperature range 10-90 degrees C using differential scanning densimetry. These data, together with those reported previously, have been used to derive the partial molar volumes of the side-chains of all 20 amino acids. The side-chain volumes are criticall y compared with literature values derived using partial molar volumes for a lternative model compounds. The new amino acid side-chain volumes, along wi th that for the backbone glycyl group, were used to calculate the partial s pecific volumes of several proteins in aqueous solution. The results obtain ed are compared with those observed experimentally. The new side-chain volu mes have also been used to redetermine residue volume changes upon protein folding. (C) 1999 Elsevier Science B.V. All rights reserved.