Gravimetric study of the sorption of water vapour by bovine serum albumin

Abstract

The sorption of water vapour in the relative vapour pressure range 0.05 to 0.95 by bovine serum albumin isolated at pH values of 2.0, 4.0, 7.5 and 10.2 has been studied using a vacuum microbalance. Water vapour sorption was dependent on the number of ionic sites, particularly charged carboxylate groups, present in the protein. The existence of intramolecular ion pair bonds between charged side chain groups inhibited the sorption of water. Water was also sorbed onto peptide groups in the main protein chain at high relative vapour pressures.