Probing plasma clearance of the thrombin–antithrombin complex with a monoclonal antibody against the putative serpin–enzyme complex receptor‐binding site

• Published in: European journal of biochemistry Vol. 270; no. 20; pp. 4059 - 4069
• Main Authors: Long, George L., Kjellberg, Margareta, Villoutreix, Bruno O., Stenflo, Johan
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.10.2003
• Subjects: Animals; Antibodies, Monoclonal - immunology; antithrombin; Antithrombin III - immunology; Antithrombin III - metabolism; Basic Medicine; Blotting, Western; Cattle; Epitopes; Humans; Läkemedelskemi; Medical and Health Sciences; Medicin och hälsovetenskap; Medicinal Chemistry; Medicinska och farmaceutiska grundvetenskaper; monoclonal antibody; Peptide Hydrolases - blood; Peptide Hydrolases - immunology; Peptide Hydrolases - metabolism; Rabbits; Serpins - immunology; serpin–enzyme complex receptor; thrombin; Thrombin - antagonists & inhibitors; thrombin–antithrombin complex; Time Factors
• ISSN: 0014-2956; 1432-1033
• DOI: 10.1046/j.1432-1033.2003.03793.x

A high‐affinity monoclonal antibody (M27), raised against the human thrombin–antithrombin complex, has been identified and characterized. The epitope recognized by M27 was located to the linear sequence FIREVP (residues 411–416), located in the C‐terminal cleavage peptide of antithrombin. This region overlaps, by two residues, the putative binding site of antithrombin for the serpin–enzyme complex receptor. Studies in rats and with HepG2 cells in culture indicated that the Fab fragment of M27 does not block binding and uptake of the thrombin–antithrombin complex, suggesting that this region does not play a major role in the recognition and clearance of the thrombin–antithrombin complex. M27 blocked the ability of antithrombin to inhibit thrombin as well as antithrombin cleavage, both in the presence and absence of heparin.