Unfolding of a protein molecule in solution with ageing and thermal denaturation as determined by a reverse dye partition technique

Abstract

A chloroform solution of an anionic dye bound to polymethyl methacrylate having an amino endgroup is partitioned with an extremely dilute solution (< 0.001 per cent) of a protein at a suitable pH. The amount of dye which gets transferred to the aqueous layer is a measure of the available excess of carboxyl over amino group of the protein. This value increases considerably with age and also with heat denaturation of the protein and so this gives an insight into conformational change or unfolding of the protein molecule as due to thermal denaturation and ageing characteristics. The same method has also been applied with success to determine, the carboxyl content of polyacrylamide (partially hydrolysed), carboxymethyl cellulose, gum arabie, copolymers containing acrylic, methacrylic and crotonic acids, and graft polymers containing acrylic acid.