Methods for removing suspended particles from soluble protein solutions

Abstract

The present invention provides soluble protein solutions, free of suspended particles in high yield. More particularly, the current invention provides a method for removing suspended particles from soluble protein solutions by filtering the soluble protein solution through highly purified diatomaceous earth.

1 - 23 . (canceled)  
     
     
         24 . A method for removing suspended particles from a soluble protein solution comprising the steps of: 
 filtering the soluble protein solution through highly purified diatomaceous earth, thereby providing a clarified soluble protein solution, and further comprising the step of reducing the amount of DNA and endotoxins, wherein the protein solution is a lysate.    
     
     
         25 . The method of  claim 24 , wherein the soluble protein solution is a secreted protein solution.  
     
     
         26 . The method of  claim 24 , wherein the lysate is a bacterial lysate.  
     
     
         27 . The method of  claim 24 , wherein the lysate comprises a heterologous protein that was obtained by expression.  
     
     
         28 . The method of  claim 24  in which the amount of DNA in the lysate is reduced by between about 100-fold and about 150-fold.  
     
     
         29 . The method of  claim 24  in which the amount of endotoxins in the lysate is reduced by between about 1000-fold and about 10,000-fold.  
     
     
         30 . The method of  claim 24  in which the turbidity of the soluble protein solution is reduced by between about 200-fold and about 300-fold.  
     
     
         31 . The method of  claim 26  in which the bacteria is  E. coli.    
     
     
         32 . The method of  claim 24  further comprising the step of purifying the proteins.  
     
     
         33 . The method of  claim 24  wherein the step of reducing the amount of DNA and endotoxins comprises flocculation with polyethyleneimine at between about pH 7.3 and about pH 7.7.  
     
     
         34 . The method of  claim 24  further comprising the step of stirring the soluble protein solution with a highly purified diatomaceous earth before filtering through a filter press.  
     
     
         35 . The method of  claim 26  wherein the lysate is a comprises SY161, wherein SY161 has an amino acid sequence as shown in SEQ ID NO: 1.  
     
     
         36 . The method of  claim 24  further comprising the step of resolubilizing refractile bodies in the lysate.  
     
     
         37 . The method of  claim 28  wherein the yield of the soluble protein solution is between about 95% and about 100%.  
     
     
         38 . The method of  claim 29  wherein the yield of the soluble protein solution is between about 95% and about 100%.  
     
     
         39 . The method of  claim 30  wherein the yield of the soluble protein solution is between about 95% and about 100%.