Partial specific volumes and interactions with solvent components of alpha-globulin from Sesmum indicum L. in urea and guanidine hydrochloride.

The interaction of α-globulin with urea/guanidine hydrochloride was
investigated by determining the apparent partial specific volumes of the protein in these
solvents. The apparent partial specific volumes were determined both under isomolal and
isopotential conditions. The preferential interaction parameter with solvent components
calculated were 0.08 and 0.1 g of urea and guanidine hydrochloride respectively per g protein.
In both the cases the interaction was not preferential with water. The total binding of
denaturant to α-globulin was calculated both for urea and guanidine hydrochloride and the
correlation between experimentally determined number of mol of denaturant bound per mol
of protein and the total number of peptide bonds and aromatic amino acids were found to be in
excellent agreement with each other. The changes in volume upon transferring α-globulin
from a salt solution to 8 Μ urea and 6 Μ guanidine hydrochloride were also calculated.