Human antithrombin III heterogeneity: a study by isoelectrofocusing and crossed immunoelectrofocusing.

Isoelectrofocusing was carried out in the LKB Multiphor apparatus with pH 4-6.5 carrier ampholines using polyacrylamide gel slabs. Specimens of purified antithrombin III (AT-III), normal plasma and serum were isoelectrofocused. Microheterogeneity was shown by three preparations of purified AT; the protein was separated in at least six bands, three large bands were located in the pH range 4.9-5.2, one intermediate band at pH 4.85, other thinner bands were located in the pH range 4.55-4.80. The microheterogeneity of AT-III was confirmed in purified preparations as well as in plasma and in serum by crossed immunoelectrofocusing. The pattern of purified preparations, normal plasma and serum were very similar; only minor, quantitative differences were noticed. Plasma from a patient with congenital AT-III deficiency showed an abnormal pattern.