As regards document (17), Example 1 therein, which is found also in its first priority document dated 7 June 1982, discloses indeed a method of purification of Met-prochymosin from an insoluble aggregate which comprises the same steps as the method of claim 14 at issue, ie solubilisation of the protein with a denaturing agent such as urea or GuHCl, and renaturation to a biologically active form by