Patent ID: 7834161

Claim:
A non-denaturing process for obtaining a heterologous protein of interest produced in a plant, comprising (a) providing a fusion protein comprising said heterologous protein fused to a carbohydrate binding module (CBM) intercepted by a proteolytic cleavage site, wherein the carbohydrate binding module does not bind to plant cell-wall material and wherein the fusion protein is soluble in a liquid phase obtained from adding extraction liquid to a disrupted plant material, (b) contacting said fusion protein with a functional protease fused to a CBM, at conditions facilitating proteolytic cleavage by said protease, to cleave the CBM from the heterologous protein of interest, (c) contacting the solution of CBM-protease, free CBM and heterologous protein of interest to a polysaccharide matrix, under conditions where the CBM-protease and free CBM binds to said polysaccharide matrix and where the heterologous protein of interest is not retained on said polysaccharide matrix, (d) separating the non-bound heterologous protein of interest from the polysaccharide matrix, (e) washing the polysaccharide matrix with the bound CBM-protease and CBM, with one or more suitable aqueous solutions, (f) eluting the CBM-protease from the matrix by adjusting conditions effecting the release of said CBM-protease off the matrix; and (g) optionally reconditioning said eluted CBM-protease, to retain its affinity to said polysaccharide matrix, such that the reconditioned CBM-protease can be re-used for subsequent repetition of the process defined by steps (a)-(g), wherein said CBMs are capable of binding reversibly to a polysaccharide matrix and being released from such matrix by non-denaturing elution conditions.