[Evidence of type-specific microheterogeneity of thyroxine-binding globulin by isoelectric focusing (author's transl)].

A rapid method for the isolation of the thyroxine-binding globulin from only 150 ml plasma is described. The preparation of a high-activity thyroxine-sepharose is essential; this contained L-thyroxine bound exclusively by covalent linkage. Furthermore, the elution of the protein was performed under specifically hydrophobic conditions. Using isoelectric focusing on 15 individual preparations of thyroxine-binding globulin, and densitometric analysis of the polyacrylamide gels, it was possible to show three protein bands in different proportions according to the individual. Three distribution-types were found in the tested volunteers. The results of this investigation show that these types are individual-specific, whereas there are no apparent sex-specific differences.