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

Area of Science:

• Biochemistry
• Proteomics

Background:

• Antithrombin III (AT-III) is a critical plasma protein regulating coagulation.
• Understanding AT-III's structural characteristics is essential for diagnosing related deficiencies.

Purpose of the Study:

• To investigate the microheterogeneity of purified antithrombin III (AT-III).
• To compare the isoelectric focusing patterns of AT-III in purified preparations, normal plasma, and serum.
• To identify potential alterations in AT-III patterns in congenital deficiency.

Main Methods:

• Isoelectrofocusing (IEF) using polyacrylamide gel slabs with pH 4-6.5 carrier ampholines.
• Analysis of purified AT-III, normal plasma, and serum specimens.
• Crossed immunoelectrofocusing (CIEF) for confirmation of microheterogeneity.

Main Results:

• Purified AT-III demonstrated microheterogeneity, separating into at least six bands across a pH range of 4.55-5.2.
• IEF patterns of purified AT-III, normal plasma, and serum were largely similar, with minor quantitative variations.
• Plasma from a patient with congenital AT-III deficiency displayed an aberrant isoelectric focusing pattern.

Conclusions:

• Antithrombin III exhibits significant microheterogeneity, observable in purified forms and biological fluids.
• Crossed immunoelectrofocusing confirms the microheterogeneity of AT-III.
• Aberrant AT-III patterns in IEF may indicate congenital deficiencies.