The influence of the underlying surface on the cataphoretic mobility of adsorbed proteins

Abstract

Measurements have been made of the electrokinetic properties, in aqueous soln., of proteins adsorbed on different surfaces. In gelatine, the cataphoretic mobility was independent of the nature of the underlying surface, which is in agreement with the results of other workers. Exps. made on the rate of adsorption showed that surface equilibrium of the protein was reached in a few seconds in strong solutions (10-1 gm./l.), but took several hours in dilute sols. Oxy- and carboxy-hemoglobin showed a sharp adsorption maximum (indicating that the surface was saturated), but the cataphoretic mobility and apparent isoelectric point depended to a marked degree on the nature of the underlying surface. The reason for this is discussed. Both the oxyhemoglobin and the carboxy-hemoglobin had identical electrokinetic properties when adsorbed, and no evidence was found for two forms of hemoglobin possessing different isoelectric points.