LIPOPOLYSACCHARIDE (LPS)-BINDING PROTEINS BPI AND LBP FORM DIFFERENT TYPES OF COMPLEXES WITH LPS

Lipopolysaccharide (LPS)-binding protein (LBP) and bactericidal/permea bility-increasing protein (BPI) are closely related LPS binding protei ns whose binding to LPS has markedly different functional consequences , To gain better insight into the possible basis of these functional d ifferences, the physical properties of LBP-LPS and BPI-LPS complexes h ave been compared in this study by sedimentation, light scattering, an d fluorescence analyses, These studies reveal dramatic differences in the physical properties of LPS complexed to LBP versus BPI, They sugge st that of the two proteins, only LBP can disperse LPS aggegates, Howe ver, BPI can enhance both the sedimentation velocity and apparent size of LPS aggregates while inhibiting LPS-LBP binding even at very low ( 1:40 to 1:20) BPI:LPS molar ratios.