Identification of the site of binding of sulfated, low molecular weight lignins on thrombin

► Sulfated LMWLs are novel allosteric inhibitors of human thrombin. ► Site-directed thrombin mutants were used to identify the site of binding of sulfated LMWLs. ► Arg93 and Arg175 were found to be key residues for recognizing sulfated LMWLs. ► The identification of this novel allosteric site on thrombin will greatly assist the design of new anticoagulants.