Disclosed is an isolated plasminogen variant or plasmin obtained from it, or an isolated plasmin variant, or a proteolytically active or reversible inactive derivative of any of the plasmins characterised in that: it comprises in its catalytic domain a mutation of the amino acid glutamate at position 138 of the human plasmin catalytic domain, or of the corresponding amino acid residue of a non-human plasmin catalytic domain. Also disclosed is a method for screening for an autoproteolytically stable plasmin variant.
