Separation of transcobalamin II isoproteins by means of chromatofocusing.

Transcobalamin II, the principal cobalamin-binding protein in human plasma, expresses a genetic polymorphism. Four more or less common alleles, denoted by X, S, M and F, have been defined earlier by means of gel electrophoretic techniques followed by autoradiography. This technique is less suitable for the analysis of individual samples and requires long exposure times. This paper describes the analysis of transcobalamin II phenotypes by means of fast protein liquid chromatofocusing. This technique has the advantage that the results of the analysis of several samples can be obtained within a day, and it also seems applicable to the preparative separation of transcobalamin II isoproteins. The sequence of elution of the isoproteins was in complete accordance with the banding pattern obtained by electrophoretic separation. The characteristic doublet bands found with polyacrylamide gel electrophoresis were less obvious in the chromatofocusing elution pattern.