Procollagen (III) Propeptides and Related Substances for Treating Fibrotic Diseases

A method of producing at least one of a renatured N-terminal procollagen (III) propeptide and a renatured C-terminal procollagen (III) propeptide, comprising the steps of:

• a) producing inclusion bodies in E. coli, wherein the inclusion bodies are dissolved in a 0.5 to 8 M denaturing buffer;
• b) pipetting the buffer of step a) dropwise into a limited dilution buffer, buffered around neutral pH and containing L-arginine in a final concentration between 200 to 1,000 nM and a disulifide bridge-reducing coupled redox system, until a volume ratio of maximally 1:3 is reached of the denaturing buffer and the limited dilution buffer, respectively;
• c) dialyzing the buffer mixture of step b) for at least 2 hours against a physiological buffer that contains L-arginine at a final concentration of 50 to 200 nM and a disulifide bridge-reducing coupled redox system;
• d) dialyzing the buffer mixture of step c) for at least 2 hours against a physiological buffer that contains a disulfide bridge-reducing coupled redox system;
• e) dialyzing the buffer mixture according to step d) against a physiological buffer for at least 2 hours.