Sol collagen prodn from human tissue - treated to remove non-helical peptides and reduce risk of infection/rejection

Sol. native collagen is made from human tissue, esp. placenta, by firstly comminuting the purified tissue in the presence of ice, stirring it in a cold saline soln., centrifuging, sepg. the centrifugate (A), which contains predominantly monomers, stirring the solid residue in a cold aqs. urea soln. opt. contg. ascorbic acid, sepg. the centrifugate (B), stirring it with a cold aqs. soln. contg. ethyl urethane, centrifuging, sepg. the centrifugate (C), dialysing (A)+(B)+(C) with tap water till complete pptn. has occurred, centrifuging off the impure collagen that has pptd., dissolving it in dil. aqs. carboxylic acid soln., pptg. the remaining impurities by adding salt till the soln. is satd. and storing the dispersion of pure collagen obtd. in a dil. carboxylic acid soln. The collagen is used as the active ingredient in cosmetic/healing formulations. The present process partially or completely removes the non-helical peptides from the collagen and thus reduces the risk of infection or antigen reaction when it is used for healing purpose.