Interference of phenol during quantification of a bacterial lipoprotein

Abstract

Accurate protein estimation is an essential requirement for any biochemical investigation. The bacterial Braun liporotein (BLP) from E. coli (a Toll-2 receptor ligand) is purified via phenol extraction on the basis of selective extraction of the lipoprotein. The procedure leaves behind the major endotoxin lipopolysaccharide (LPS) that acts through the related Toll-4 receptor. However, as low as 0.00001% of phenol carried over during lipoprotein isolation interferes in the Lowry’s method of protein estimation. A simple gel filtration on sephadex G-50 efficiently separates lipoproteins from phenol thereby avoiding inaccurate protein estimation of the lipoprotein content and making it suitable ligand for Toll-2 receptor.