In addition to phospholipids and proteins, the outer layer of the cell membrane of Gram-negative bacteria has a separate structure called lipopolysaccharide (LPS), the properties of which vary from bacteria to bacteria. This lipopolysaccharide is known to play an important role not only in the growth or survival of bacteria but in many roles, especially in the interaction between host and parasite. In addition, LPS is thought to be closely related to the immune response. Bacterial endotoxins are substances commonly found in the outer cell walls of Gram-negative bacteria that are not present when the bacteria are alive but are released when the bacteria multiply or die when the cell wall ruptures. The endotoxin in its natural state is composed of lipopolysaccharide, protein, and phospholipid, which is very stable, heat-resistant, negatively charged, and has a large molecular weight. Typically, proteins are obtained by extraction with trichloroacetic acid, butanol, or EDTA to remove lipid-associated proteins (LAPs), and phospholipids are extracted with phenol. When we usually try to extract LPS, about 1~4% LPS can be obtained per dry weight of bacteria. The LPS extraction kit is based on the phenol-water method, so this kit denatures the proteins in endotoxins, which are then removed by denaturation in the form of precipitation between the aqueous layer and the phenolic layer. qualitative fractionation. Chloroethers are formed so only dense LPS can be extracted quickly and easily.
