Patent ID: 7993899

Claim:
A method for purifying chymosin comprising: (i) contacting an aqueous liquid sample containing chymosin with a separation medium comprising a base matrix and a plurality of attached ligands that are capable of binding to chymosin, wherein the pH of the aqueous sample is about or lower than the pI of chymosin and (ii) desorbing the chymosin with an aqueous buffer from the separation medium at a pH which is higher than the pI of chymosin, wherein said base matrix is hydrophilic and each ligand consists of a) a hydrocarbon group of 1-12 carbon atoms wherein all of the carbon atoms are sp 3 -hybridized, b) a hydrocarbon group of 1-12 carbons atoms wherein all of the carbon atoms are sp 3 -hybridized having one or more oxygen (O) or sulphur (S) atoms inserted between two carbon atoms of the hydrocarbon group, wherein the ratio of the sum of sulphur and oxygen atoms to the number of carbon atoms in each ligand is <1, c) a hydrocarbon group of 1-12 carbon atoms wherein all of the carbon atoms are sp 3 -hybridized and at least one of the hydrogen atoms is substituted by a hydroxyl group, or combination of said ligands, wherein the separation matrix consists only of ligands of said hydrocarbon groups, wherein said base matrix is in the form of a porous monolith, and wherein the surfaces of the pores of said base matrix have sufficient hydrophilicity for the aqueous liquid sample to penetrate said pores.