Although collagen is useful as a medical material, there exist risks of allergies and zoonoses when used in human. There, artificial collagens or the like are being considered as medical materials. However, the conventional artificial collagens were not necessarily satisfactory in terms of, for example, physical strength, denaturation due to heating, and inability of being processed into the shape of a sheet i.e. the conventional artificial collagens have been problematic in terms of practicality. The present invention is produced as a polymerized peptide prepared by oxidatively cross-linking collagen-like peptides having the triple-helical structure containing three peptide chains each containing multiple cysteine (Cys) residues. This polymerized peptide can be processed into a hydrogel and a thin membrane sheet before use, and is capable of imparting a particular physiological function such as cellular adhesion by incorporating functional amino acid sequences present on biological polymers. Further, the present invention provides a method for producing the abovementioned polymerized peptide and the like and use applications employing the same, such as cell culturing, wound dressing, and compositions including regenerative medical materials and research materials.
