Introduction

Endotoxins (i.e., lipopolysaccharides, LPS) is the main component of the cell wall of E. coli, and lipopolysaccharide binds very strongly to DNA or protein and is easily co-purified. In the preparation of plasmid DNA and recombinant proteins, the large amount of lipopolysaccharide released after bacterial wall breaking cannot be removed cleanly, either by conventional procedures such as ion exchange, gel exclusion filtration, or advanced preparation procedures such as cesium chloride ultracentrifugation. Under specific pH and salt concentrations, endotoxin removal solutions can bind specifically to DNA/RNA, recombinant proteins, and other samples and remove endotoxins by centrifugation and concentration in the lower organic phase, generally reducing endotoxin by 1000-10000 times after 3 repeated extractions. The treated plasmid DNA can be used for transfection experiments.