Electrophoresis of Thyroxine in Protein-Free Solutions and in Sera Deficient in Binding Proteins

Abstract

The electrophoretic migration of free thyroxine has been studied and compared with the behavior of thyroxine in the presence of serum. It has been found that the inherent mobility of thyroxine probably is faster than that of human albumin and possibly is faster than that of prealbumin. However, in certain electrophoretic systems an artifact is produced by adsorption of thyroxine to the supporting medium, thus retarding its true migration. The free thyroxine, however, appears in a discrete zone as a result of chromatography during electrophoretic migration. When added to serum in which thyroxine-binding proteins are weak or lacking, some thyroxine may migrate electrophoretically as the unbound hormone. Confusion between bound and unbound thyroxine in serum may be clarified by using different techniques of electrophoresis.