Egg white processing

Abstract

This disclosure relates to inexpensive and efficient methods of preparing egg white (e.g., obtained from eggs laid by transgenic chickens) for bulk chromatographic isolation of proteins (e.g., recombinant proteins) from the egg white, as well as method of filtering acidified egg white and methods of isolating proteins from the egg white.

1 . A method of preparing egg white for bulk chromatographic processing, the method comprising the steps of:
 adding an acidic buffer comprising an acidic agent to a pool of egg white, the acidic buffer being from about 0.5 wt % to about 5 wt % per kilogram of the egg white; and   mixing the acidic buffer and the egg white to form a mixed egg white having a pH from about 5 to about 6.5.   
     
     
         2 . The method of  claim 1 , wherein the acidic agent is selected from the group consisting of acetic acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid, perchloric acid, citric acid, boric acid, tartaric acid, lactic acid, formic acid, oxalic acid, uric acid, and barbituric acid. 
     
     
         3 . The method of  claim 2 , wherein the acidic buffer further comprises from about 5M to about 6M sodium acetate. 
     
     
         4 . (canceled) 
     
     
         5 . The method of  claim 1 , wherein the acidic buffer is from about 0.5 wt % to about 2 wt % per kilogram of the egg white. 
     
     
         6 - 7 . (canceled) 
     
     
         8 . The method of  claim 1 , wherein the acidic buffer has a pH from about 4 to about 6.5. 
     
     
         9 - 10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein the pH of the mixed egg white is from about 5 to about 6.3. 
     
     
         12 - 16 . (canceled) 
     
     
         17 . The method of  claim 1 , wherein the egg white is mixed for at least about 1 hour. 
     
     
         18 . The method of  claim 1 , wherein the egg white is mixed at a temperature from about 2° C. to about 25° C. 
     
     
         19 . The method of  claim 1 , wherein the egg white pool has a volume of at least about 10 liters. 
     
     
         20 . The method of  claim 1 , wherein the acidic buffer is added to the egg white pool in a single bolus injection. 
     
     
         21 . The method of  claim 20 , wherein the acidic buffer is added at a rate of at least about 1 L/minute. 
     
     
         22 . The method of  claim 1 , wherein the addition of the acidic buffer and the mixing of the egg white are performed concurrently. 
     
     
         23 - 28 . (canceled) 
     
     
         29 . The method of  claim 1 , further comprising filtering the mixed egg white without allowing the mixed egg white to settle, wherein the filtering step comprises filtering the mixed egg white through a filter having an average pore size ranging from about 0.1 μm to about 100 μm. 
     
     
         30 . The method of  claim 29 , wherein the filtering step comprises one or more subsequent filtering steps following an initial filtering of the mixed egg white, the one or more subsequent filtering steps using one or more filters having an average pore size ranging from about 0.1 μm to about 40 μm. 
     
     
         31 . (canceled) 
     
     
         32 . The method of  claim 1 , wherein the egg white comprises a recombinant therapeutic protein exogenous to egg white. 
     
     
         33 - 38 . (canceled) 
     
     
         39 . The method of  claim 1 , further comprising the steps of:
 passing a pre-treatment buffer having a conductivity between about 8 mS/cm and about 20 mS/cm through a filter; and   passing egg white having a pH from about 5 to about 6.5 through the filter to obtain a filtered egg white.   
     
     
         40 . The method of  claim 39 , wherein the pre-treatment buffer has a pH substantially the same as the pH of the egg white. 
     
     
         41 . The method of  claim 40 , wherein the pre-treatment buffer has a pH from about 5.9 to about 6.1. 
     
     
         42 . (canceled) 
     
     
         43 . The method of  claim 39 , wherein the pre-treatment buffer comprises sodium phosphate and sodium chloride. 
     
     
         44 - 50 . (canceled) 
     
     
         51 . A recombinant protein isolated from egg white according to the method of  claim 1 .