Patent ID: 7390936

Claim:
A method for the production and isolation of chymosin in a plant seed comprising an oil fraction said method comprising: a) introducing into a plant cell a chimeric nucleic acid molecule comprising in the 5′ to 3′ direction of transcription: 1) a seed-specific promoter capable of regulating transcription in said plant cell operatively linked to; 2) a second nucleic acid sequence encoding a chymosin polypeptide and comprising SEQ ID NO:1 operatively linked to; 3) a third nucleic acid sequence capable of terminating transcription in said plant cell; b) growing said plant cell into a mature plant capable of setting seed wherein said seed contains chymosin; c) obtaining seed from the mature plant wherein the seed contains at least 0.5% (w/w) chymosin; and d) isolating said chymosin from said seed using a method comprising: (i) crushing the plant seed in the presence of water or a buffer to obtain crushed plant seed; (ii) fractionating the crushed plant seed into an oil fraction, aqueous fraction and a fraction comprising insoluble material; (iii) contacting the aqueous fraction with a protein binding resin; and (iv) recovering chymosin from the protein biding resin such that said chymosin is purified and biologically active.