Thrombin allosteric modulation revisited: a molecular dynamics study.
Research article published in Journal of molecular modeling (2009)
Abstract
The regulatory properties of thrombin are derived predominantly from its capacity to produce different functional conformations. Functional studies have revealed that two antagonistic thrombin conformations exist in equilibrium: the fast (procoagulant) and slow (anticoagulant) forms. The mechanisms whereby thrombin activity is regulated by the binding of different effectors remain among the most enigmatic and controversial subjects in the field of protein function. In order to obtain more detailed information on the dynamic events originating from the interaction with the Na(+) effector and ligand binding at the active site and anion binding exosite 1 (ABE1), we carried out molecular dynamics simulations of thrombin in different bound states. The results indicated that Na(+) release results in a more closed conformation of thrombin, which can be compared to the slow form. The conformational changes induced by displacement of the sodium ion from the Na-binding site include: (1) distortion of the 220- and 186-loops that constitute the Na-binding site; (2) folding back of the Trp148 loop towards the body of the protein, (3) a 180 degrees rotation of the Asp189 side-chain, and (4) projection of the Trp60D loop toward the solvent accompanied by the rearrangement of the Trp215 side chain toward the 95-100 loop. Our findings correlate well with the known structural and recognition properties of the slow and fast forms of thrombin, and are in accordance with the hypothesis that there is communication between the diverse functional domains of thrombin. The theoretical models generated from our MD simulations complement and advance the structural information currently available, leading to a more detailed understanding of thrombin structure and function.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
The regulatory properties of thrombin are derived predominantly from its capacity to produce different functional conformations. Functional studies have revealed that two antagonistic thrombin conformations exist in equilibrium: the fast (procoagulant) and slow (anticoagulant) forms.
Why This Matters for Hirudotherapy
This study utilized molecular dynamics simulations to explore the allosteric regulation of thrombin, specifically the conformational changes triggered by sodium ion release and ligand binding at the active site and anion binding exosite 1 (ABE1). The findings map the dynamic structural shifts between the procoagulant 'fast' and anticoagulant 'slow' forms of thrombin. This computational work matters to the ASH domain because ABE1 and the active site are prime targets for leech-derived anticoagulants, such as hirudin. Detailed models of thrombin's functional domains and communication pathways help elucidate the molecular environment in which leech secretions exert their therapeutic effects. The limitation is that this is a purely theoretical, computational study with no leeches, biological assays, or clinical data involved; its connection to hirudotherapy is entirely indirect and mechanistic.
Citation
Thrombin allosteric modulation revisited: a molecular dynamics study.
de Amorim et al. · Journal of molecular modeling, 2009
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