Some Electrophoretic Studies of Proteins in the Adsorbed State

Abstract

The electrophoretic mobility of bovine γ-globulin, haemoglobin, and insulin adsorbed upon particles of different chemical types (mostly hydrocarbon derivatives) has been studied as a function of protein concentration and of pH. On the majority of the surfaces used the isoelectric points of the bovine γ-globulin and insulin were 6.0 and 5.0 respectively. However, with certain particles, especially cetyl alcohol, a marked shift in the isoelectric point was observed and on either side of the isoelectric point the mobility depended to a certain extent upon the nature of the particle. These effects have been ascribed to two causes : (a) a specific reaction between the protein and the particle and (b) an incomplete coverage of the particle by the protein. Insulin adsorbed upon particles became more negatively charged on standing. probably due to the insulin dissociating into smaller units.