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Mapping the Binding Site of an Aptamer on ATP Using MicroScale Thermophoresis
08:09

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RNA aptamer to thrombin binds anion-binding exosite-2 and alters protease inhibition by heparin-binding serpins

Martha L Jeter1, Linda V Ly, Yolanda M Fortenberry

  • 1Department of Pathology and Laboratory Medicine, Carolina Cardiovascular Biology Center, The University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599-7035, USA.

FEBS Letters
|June 16, 2004
PubMed

We studied the RNA aptamer Toggle-25/thrombin interaction during inhibition by antithrombin (AT), heparin cofactor II (HCII) and protein C inhibitor (PCI). Thrombin inhibition was reduced 3-fold by Toggle-25 for AT and HCII, but it was slightly enhanced for PCI. In the presence of glycosaminoglycans, AT and PCI had significantly reduced thrombin inhibition with Toggle-25, but it was only reduced 3-fold for HCII. This suggested that the primary effect of aptamer binding was through the heparin-binding site of thrombin, anion-binding exosite-2 (exosite-2). We localized the Toggle-25 binding site to Arg 98, Glu 169, Lys 174, Asp 175, Arg 245, and Lys 248 of exosite-2. We conclude that a RNA aptamer to thrombin exosite-2 might provide an effective clinical reagent to control heparin's anticoagulant action.

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