Method for stabilizing polypeptides lacking methionine

Abstract

Methionine is an effective antioxidant for polypeptides having an amino acid sequence lacking methionine. Compositions containing polypeptides having an amino acid sequence that is free of methionine residues are stabilized from oxidative degradation by combining methionine in the composition in an amount effective to inhibit oxidation of the polypeptide.

1 . A method for inhibiting degradation of a liquid or semi-solid composition containing a polypeptide having an amino acid sequence that does not include methionine, comprising combining free methionine in the composition in an amount sufficient to inhibit oxidation of the polypeptide.  
   
   
       2 . The method of  claim 1  wherein the composition is an aqueous solution.  
   
   
       3 . The method of  claim 1  wherein the composition is an oil-in-water emulsion.  
   
   
       4 . The method of  claim 1  wherein the molar ratio of methionine:polypeptide in the composition is 10:1 or higher.  
   
   
       5 . The method of  claim 1  wherein the molar ratio of methionine:polypeptide in the composition is 20:1 or higher.  
   
   
       6 . The method of  claim 1  wherein the molar ratio is 100:1 or higher.  
   
   
       7 . The method of  claim 1  wherein the molar ratio is 200:1 or higher.  
   
   
       8 . A composition comprising a polypeptide having an amino acid sequence that is free of methionine and free methionine at a concentration that is effective to inhibit degradative oxidation of the polypeptide.  
   
   
       9 . The composition of  claim 8  which is an aqueous solution.  
   
   
       10 . The composition of  claim 8  which is an oil-in-water emulsion.  
   
   
       11 . The composition of  claim 8  wherein the molar ratio of methionine:polypeptide in the composition is 10:1 or higher.  
   
   
       12 . The composition of  claim 8  wherein the molar ratio of methionine:polypeptide in the composition is 20:1 or higher.  
   
   
       13 . The composition of  claim 8  wherein the molar ratio is 100:1 or higher.  
   
   
       14 . The composition of  claim 8  wherein the molar ratio is 200:1 or higher.