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A monoclonal antibody that triggers deacylation of an intermediate thrombin-antithrombin III complex.

Authors
  • Asakura, S
  • Matsuda, M
  • Yoshida, N
  • Terukina, S
  • Kihara, H
Type
Published Article
Journal
The Journal of biological chemistry
Publication Date
Aug 15, 1989
Volume
264
Issue
23
Pages
13736–13739
Identifiers
PMID: 2474535
Source
Medline
License
Unknown

Abstract

Upon incubation of antithrombin III with thrombin in the presence of a monoclonal antibody recognizing an epitope exposed on the heavy chain part of thrombin-cleaved two-chain antithrombin III, antithrombin III was preferentially cleaved by the enzyme as a substrate, rather than covalently complexed with the enzyme to form an equimolar, stable acyl complex. Once the stable acyl complex was formed between the enzyme and antithrombin III, however, no further liberation of two-chain antithrombin III was observed. Kinetic studies showed that heparin does not affect this reaction, although generation of thrombin-cleaved two-chain antithrombin III is apparently accelerated in accordance with the rate constant for heparin-enhanced thrombin-antithrombin III complex formation. Here we propose the term "switching antibody" for an antibody that triggers deacylation of an intermediate enzyme-inhibitor complex by switching the enzyme-inhibitor reaction from the major pathway of stable acyl complex formation to an alternative pathway of cleavage of the inhibitor as a substrate.

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