Total synthesis of homogeneous variants of hirudin P6: A post-translationally modified anti-thrombotic leech-derived protein

Hirudin P6 is a leech-derived anti-thrombotic protein which possesses two post-translational modifications, O-glycosylation and tyrosine sulfation. In this study we report the ligation-based synthesis of a library of hirudin P6 proteins possessing homogeneous glycosylation and sulfation modifications. The nature of the modifications incorporated was shown to have a drastic effect on inhibition against both the fibrinogenolytic and amidolytic activities of thrombin and thus highlights a potential means for attenuating the biological activity of the protein. Modifications matter: Hirudin P6 is a leech-derived anti-thrombotic protein that is natively O-glycosylated and sulfated on tyrosine. Ligation chemistry was employed to assemble a library of homogeneously modified hirudin P6 proteins with variation in glycosylation at Thr-43 and sulfation at Tyr-61. The type of post-translational modification present was shown to have a dramatic effect on inhibitory activity against both the fibrinogenolytic and amidolytic activities of thrombin.