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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Bezeaud, A. Articles by Guillin, M. C. Search for Related Content PubMed PubMed Citation Articles by Bezeaud, A. Articles by Guillin, M. C. Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Functional characterization of thrombin Salakta: an abnormal thrombin derived from a human prothrombin variant A Bezeaud, J Elion and MC Guillin Laboratoire de Recherche sur l'Hemostase et la Thrombose, Faculte Xavier Bichat, Paris, France. The genetic variant prothrombin Salakta has been described in a patient presenting with a normal level of prothrombin antigen but reduced prothrombin activity. Initial studies indicated that factor Xa- catalyzed cleavages proceed normally but lead to the production of a thrombin molecule with an altered enzymatic activity. To characterize the functional abnormality of thrombin Salakta more precisely, it was purified by chromatography on heparin-Sepharose and diethylaminoethyl- Sephadex. The purified variant does not differ from normal thrombin by size, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and is 93.1% +/- 7.6% active by titration with p- nitrophenyl-p'-guanidinobenzoate. Its activity, however, is altered to various extents toward the following substrates: H-D-phenylalanyl-L- pipecolyl-L-arginine paranitroanilide (S 2238), fibrinogen, factor V, protein C, and antithrombin III. The Michaelis constant (Km) of thrombin Salakta for S 2238 is higher (12.2 +/- 3.3 mumol/L) than normal (2.8 +/- 0.7 mumol/L), whereas the turnover number (Kcat) is normal (84.4 +/- 6.6 s-1 v 85.9 +/- 14.0 s-1 for normal thrombin). The interaction of thrombin Salakta with benzamidine is also altered as evidenced by an increased inhibition constant (Ki = 3.5 mmol/L v 0.28 mmol/L for normal thrombin). The inability of fibrinogen to act as a competitor in the inactivation of thrombin Salakta by diisopropylfluorophosphate clearly indicates that fibrinogen binding to the fibrinopeptide groove is drastically impaired. In contrast, interactions involving sites remote from the active site such as those with fibrin and thrombomodulin are only slightly impaired. These results indicate that thrombin Salakta exhibits a specific pattern of functional alterations different from those reported for other variants. The structural defect seems to affect essentially the primary substrate binding site and to a lesser extent recognition site(s) remote from the catalytic site such as those for fibrin and thrombomodulin. Volume 71, Issue 3, pp. 556-561, 03/01/1988 Copyright © 1988 by The American Society of Hematology CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: C. d'Audigier, E. Pasmant, O. Bournier, Y. Laurian, M. C. Guillin, and A. Bezeaud A natural variant with a point mutation resulting in a homozygous Arg to His substitution at position 388 in prothrombin Haematologica, May 1, 2008; 93(5): 799 - 800. [Full Text] [PDF]

	Copyright © 1988 by American Society of Hematology         Online ISSN: 1528-0020