The present invention relates to a chimeric hirudin protein comprising a carrier attached to the N-terminus of hirudin, with an intervening plasmin cleavage site. The chimeric hirudin protein contains a relatively inactive form of hirudin. However, when such chimeric hirudin protein being cleaved by plasmin in the vicinity of a clot and, ultimately causing the release of active hirudin and the reduction of the size of the clot. The chimeric hirudin protein exhibited much slower clearance in mice than unfused wild-type hirudin.
