Effects of protein concentration and detergent on endotoxin reduction by ultrafiltration

Lipopolysaccharide (LPS), found in the outer membrane of Gram negative bacteria, only exerts its toxic effects when in free form. LPS has three major parts, lipid A, the toxic component, along with a core polysaccharide and O-specific polysaccharide. LPS monomers are known to have molecular masses between 10 to 30 kDa. Under physiological conditions, LPS exists in equilibrium between monomer and vesicle forms. LPS removal by 100 kDa ultrafiltration was more efficient (99.6% of LPS removed) with a low concentration of protein (2.0 mg/ml) compared to a high concentration (20.1 mg/ml). In the presence of different detergents (0.5% Tween 20, 1.0% taurodeoxycholate and 1.0% Triton X-100), LPS removal was more efficient at low protein concentrations (2.0 mg/ml) compared to high protein concentrations (20.1 mg/ml).