Method for purifying calcium ion-binding protein

Abstract

The present invention relates to a method for purifying a calcium ion-binding protein by cation exchange chromatography. The present invention provide a method for isolating and purifying a calcium ion-binding protein in a simple and efficient manner from a liquid sample containing a calcium ion-binding protein and contaminants without any pretreatment such as addition of a chelating agent. More specifically, the present invention relates to a method for purifying a calcium ion-binding protein which comprises contacting said protein with a cation exchange carrier in the presence of calcium ions to let the said protein be adsorbed to the carrier, and after washing, eluting said protein, and to a calcium ion-binding protein having substantially no contaminants obtained by the method of the present invention.

1 . A calcium ion-binding protein selected from the group consisting of Annexins I, II, III, IV, V, VI and VII having a purity of 80 to 100% as determined by gel filtration chromatographic analysis, obtained by a method, comprising: 
 contacting a sample containing said protein with a cation exchange carrier in the presence of calcium ions to let the protein be adsorbed to the exchange carrier; and    eluting the adsorbed calcium ion-binding protein from the exchange carrier by 
 (a) decreasing or removing the concentration of said calcium ions  
 (b) adding counter ions other than said calcium ions or  
 (c) both (a) and (b).  
   
     
     
         2 . A calcium ion-binding protein selected from the group consisting of Annexins I, II, III, IV, V, VI and VII having a purity of 80 to 100% as determined by gel filtration chromatographic analysis or SDS-PAGE analysis, obtained by a method, comprising: 
 contacting a sample containing said protein with a cation exchange carrier in the presence of calcium ions to let the protein be adsorbed to the exchange carrier; and    eluting the adsorbed calcium ion-binding protein from the exchange carrier by 
 (a) decreasing or removing the concentration of said calcium ions  
 (b) adding counter ions other than said calcium ions or  
 (c) both (a) and (b).  
   
     
     
         3 . A calcium ion-binding protein selected from the group consisting of Annexins I, II, III, IV, V, VI and VII having a purity of 80 to 100% as determined on a molecular size basis, obtained by a method, comprising: 
 contacting a sample containing said protein with a cation exchange carrier in the presence of calcium ions to let the protein be adsorbed to the exchange carrier; and    eluting the adsorbed calcium ion-binding protein from the exchange carrier by 
 (a) decreasing or removing the concentration of said calcium ions  
 (b) adding counter ions other than said calcium ions or  
 (c) both (a) and (b).