Removing endotoxin from proteins
Disclosed is a method for removing endotoxin from proteins. Also disclosed are products made by using the method. The method may be used, for example, to produce endotoxin-free lactoferrin. Bovine milk-derived lactoferrin may be produced in commercial quantities by the method, and endotoxin-free bovine lactoferrin may be used for a variety of therapeutic uses, including improving wound healing.
1. A method for removing bound endotoxin from an endotoxin-binding protein, the method comprising
a) binding the endotoxin-binding protein to a cation exchange resin;
b) eluting the bound endotoxin from the endotoxin-binding protein using a low-ionic strength solution in the absence of added surfactant; and
c) eluting the endotoxin-binding protein with a high ionic strength solution.
2. The method of claim 1 wherein the low-ionic strength solution is a 0.01 to 0.5 molar salt solution.
3. The method of claim 2 wherein the low-ionic strength solution is a 0.25 to 0.35 molar salt solution.
4. The method of claim 1 wherein the high ionic strength solution is an 80-100 mS/cm salt solution.
5. The method of claim 1 additionally comprising the steps of filtering the eluted protein and drying the eluted protein.
6. The method of claim 1 wherein the endotoxin-binding protein is selected from the group consisting of lactoferrin, lactoferricin, and lactoperoxidase.