Heparin mechanism of action: Difference between revisions
Jump to navigation
Jump to search
Created page with "{{SI}} {{CMG}} ==Overview== ==Mechanism of action== * Heparin is an indirect thrombin inhibitor. * It forms a complexes with antithrombin / AT III (predominantly) and other fa..." |
|||
| Line 5: | Line 5: | ||
==Mechanism of action== | ==Mechanism of action== | ||
* Heparin is an indirect thrombin inhibitor. | * [[Heparin]] is an [[indirect thrombin inhibitor]]. | ||
* It forms a complexes with antithrombin / AT III (predominantly) and other factors like factor Xa, factors XIIa, XIa, and IXa, that results in a conformational change in | * It forms a complexes with [[antithrombin]] / AT III (predominantly) and other factors like factor Xa, factors XIIa, XIa, and IXa, that results in a conformational change in [[antithrombin]], converting it from a slow to a rapid inactivator of [[thrombin]]. | ||
* Antithrombin has two active sites: | * Antithrombin has two active sites: | ||
** Reactive center, Arg393-Ser394 | ** Reactive center, Arg393-Ser394 | ||
** Heparin binding sites | ** Heparin binding sites | ||
The unfractionated heparins have long saccharide units that are lacking in in the low molecular weight (LMW) heparins, and fondaparinux. These long chains of polysaccharides are required for heparins to bind to both AT and to a binding site on thrombin and formation of a tenary complex. Accordingly, LMW heparins and fondaparinux have less antithrombin activity than does unfractionated heparin [8,9]. | |||
* Direct binding to platelets | |||
* Binding to heparin cofactor II (high concentrations) . | |||
{{WH}} | {{WH}} | ||
{{WS}} | {{WS}} | ||
Revision as of 16:11, 3 December 2011
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Mechanism of action
- It forms a complexes with antithrombin / AT III (predominantly) and other factors like factor Xa, factors XIIa, XIa, and IXa, that results in a conformational change in antithrombin, converting it from a slow to a rapid inactivator of thrombin.
- Antithrombin has two active sites:
- Reactive center, Arg393-Ser394
- Heparin binding sites
The unfractionated heparins have long saccharide units that are lacking in in the low molecular weight (LMW) heparins, and fondaparinux. These long chains of polysaccharides are required for heparins to bind to both AT and to a binding site on thrombin and formation of a tenary complex. Accordingly, LMW heparins and fondaparinux have less antithrombin activity than does unfractionated heparin [8,9].
- Direct binding to platelets
- Binding to heparin cofactor II (high concentrations) .