SEPARATION OF PRE-PEAK AND POST-PEAK IN FUSION PROTEIN SAMPLE BY USING SIZE EXCLUSION HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
The present invention provides an effective High Performance Liquid Chromatography (SE-HPLC) method to separate or resolve the pre-peak, post-peak and main peak of CTLA4-IgG1 fusion protein, where pre-peak resolution is more than 1.3. The invention further provides effective separation and resolution of post peak impurity present in CTLA4 IgG1 protein. Moreover, the present invention also provides the method for the estimation and/or quantification of pre-peak, post-peak and main peak of the protein mixture.
1 . A method for the separation of CTLA4-IgG1 fusion protein mixture comprising CTLA4-IgG1 fusion protein, pre-peak and post-peak impurity thereof, the process comprises;
a) loading the CTLA4-IgG1 fusion protein mixture onto Size Exclusion High Performance Liquid Chromatography (SE-HPLC) column;
b) separating the protein mixture with suitable mobile phase comprising combination of salts at suitable pH more than pI of the fusion protein; wherein the mobile phase maintains flow rate more than 0.3 mL/min;
c) separating the pre-peak impurity and post-peak impurity from the CTLA4-IgG1 fusion protein of interest; wherein the separation has pre-peak resolution is more than 1.3.
2 . The method according to claim 1 , wherein the pre-peak, post peak and said CTLA4-IgG1 fusion protein is further quantified at suitable detection absorbance selected from about 214 nm to about 280 nm.
3 . The method according to claim 1 , wherein the protein mixture is obtained from harvest, partially purified, substantially purified by any other purification methods.
4 . The method according to claim 1 , wherein the protein mixture is obtained from affinity chromatography, preferably protein A chromatography.
5 . The method according to claim 1 , wherein the pre-peak impurity is high molecular weight and/or aggregates and post-peak impurity is low molecular weight and/or fragments of CTLA4-IgG1.
6 . The method according to claim 1 , wherein the mobile phase is selected from sodium phosphate in combination with sodium sulphate, potassium phosphate in combination with potassium chloride, sodium phosphate in combination with potassium chloride, and potassium phosphate in combination with sodium sulphate in suitable concentration selected from about 50 mM to about 150 mM.
7 . The method according to claim 6 , wherein the mobile phase is selected from sodium phosphate in combination with sodium sulphate in suitable concentration selected from about 80 mM, about 90 mM, about 100 mM, about 110 mM, and about 120 mM.
8 . The method according to claim 1 , wherein the mobile phase comprises salt selected from sodium sulphate, potassium chloride, in suitable concentration selected from about 50 mM to about 150 mM.
9 . The method according to claim 8 , wherein the salt concentration is selected from about 80 mM, about 90 mM, about 100 mM, about 110 mM, and about 120 mM.
10 . The method according to claim 1 , wherein the suitable pH is about 5.5 to about 7.0, preferably about 6.5 to about 6.7.
11 . The method according to claim 1 , wherein the mobile phase is free of sodium chloride, arginine, acetonitrile, TFA, guanidine hydrochloride, urea and formic acid.
12 . The method according to claim 1 , wherein the loading of the fusion protein mixture comprises about 30 μg/μl to about 80 μg/μl.
13 . The method according to claim 1 , wherein the separation performed at flow rate selected from about 0.4 ml/min, about 0.5 ml/min, and about 0.6 ml/min.
14 . The method according to claim 1 , wherein SE-HPLC comprises size exclusion column having silica matrix, pore size selected from about 140 Å to about 290 Å and dimension selected from 150*4.6 mm, 300*7.8 mm.
15 . The method according to claim 14 , pore size of the SE-HPLC is 14.5 nm or 145 Å to about 20 nm or 200 Å and dimension 300*7.8 mm.
16 . The method according to claim 14 , wherein the size exclusion column is BioSep-SEC-S2000, BioSep-SEC-S3000, BioSep-SEC-S4000.
17 . The method according to claim 1 , wherein the peak tailing is from about 0.7 to 1.15.
18 . The method according to claim 1 , wherein the pI of CTLA4-IgG1 is less than 6.5.
19 . The method according to claim 1 , the pre-peak area and post-peak is not merged or interfered with main peak area.
20 . The method according to claim 1 , the purity of fusion protein of interest or main peak more than 98%.