INTERACTION OF LIPOPOLYSACCHARIDE-BINDING PROTEINS WITH VARIOUS FORMS OF LIPOPOLYSACCHARIDES

Lipopolysaccharide-binding proteins from two common jellyfish species Aurellia aurita and Ropelema asamushi were isolated and purified, and the interaction of lipopolysaccharides (LPS) of various structural types with LBP was studied. By inhibiting the interaction, it was found that both proteins specifically bind to the lipid and core fragments of the LPS molecule. There are two types of binding sites in LBP with Kd = 3,28 × 10-6 M and Kd = 0,13 × 10-6 M (for the protein from A. aurita) and Kd = 3,66 × 10-6 M and Kd = 0,27 × 10-6 M (for protein from R. asamushi). It has been shown by dynamic light scattering that the binding of LBP to R-LPS leads to the dissociation of LPS micelles. The sizes of LPS aggregates decrease from 200 nm to 25–30 nm in the composition of LPS–LSB complexes. The data of electrokinetic measurements indicate the neutralization of the negative charge of Rd-LPS (-42,2 mV) in the LPS-LSB-R. asamushi complex up to -4,4 mV. S-LPS micelles from E. coli do not disaggregate upon binding to LBP, which is apparently due to the shielding of lipid A by O-specific chains in the S-LPS molecule. The binding of LPS to LBP may affect their endotoxic properties.