Diane M. Jacobs

Binding of polymyxin B to the lipid A portion of bacterial lipopolysaccharides.

Abstract The cationic polypeptide polymyxin B, has been demonstrated to form a stable molecular complex with the lipid A region of bacterial lipopolysaccharides. The interaction between polymyxin B and LPS appears to be stoichiometric, with several lines of evidence suggesting that one molecule of polymyxin B binds one monomer unit of LPS. The formation of LPS-polymyxin B complexes results in the generation of higher mol. wt aggregates with decreased isopynic density.

IDENTIFICATION AND CHARACTERIZATION OF THE CHEMICAL MOIETY OF LPS RESPONSIBLE FOR C3H/HeJ SPLEEN CELL MITOGENICITY

Publisher Summary This chapter discusses the identification and the characterization of the chemical moiety of LPS responsible for C3H/HeJ spleen cell mitogenicity. Unlike phenol-extracted LPS (P-LPS), LPS prepared by aqueous butanol extraction (BLPS) has potent mitogenic activity toward C3H/HeJ and also the responder C3H/St spleen cells. Polymyxin B (PB) has been shown to block the mitogenic response of mouse spleen cells to LPS. In a study described in the chapter, gel filtration chromatography of the phenol extract in 8 M urea revealed the presence of two low molecular weight protein fractions of equivalent specific activity. The mitogenic response to B-LPS and isolated LAP is decreased by greater than 50% following short periods of mild alkaline hydrolysis suggesting that the mitogenic activity of LAP and B-LPS is not because of lipid A.