A complex comprising at least one target protein and at least one binding molecule having a binding affinity for said target protein, wherein said molecule having a binding affinity is covalently or non-covalently bound to at least one water-soluble polymer. In specific embodiments, the invention is directed to a complex comprising at least one protein with a heparin binding site and at least one heparin or a heparin-like molecule, wherein the heparin or heparin-like molecule is covalently bound to hydroxyalkyl starch.Linvention concerne un complexe comprenant au moins une protéine cible et au moins une molécule de liaison possédant une affinité de liaison pour ladite protéine cible, cette molécule possédant une affinité de liaison étant liée de manière covalente ou non covalente à au moins un polymère soluble dans leau.
