[Protein of Escherichia coli interacting specifically with human low density lipoproteins]

Escherichia coli 48 kDa protein interacting specifically with human low-density lipoproteins is described. The dissociation constant of this highly specific interaction was found to be equal to 4 mkg LDL per 1 ml or 7.3 x 10 M, which is comparable with the dissociation constant of the complex formed by LDL and human LDL receptor. A protocol for purifying the E. Coli binding protein was developed and antibodies against this purified protein were raised. The absence of sequences with homology to the ligand-binding repeats of the human LDL receptor in E. Coli proteome was shown by computer analysis of E. Coli genome. A conclusion was made that binding of the human LDL with specific E. Coli protein is thus mediated by other sequences and by another mechanism different from that, which occurs in human cells during the interaction of lipoproteins with their specific receptor. The establishment of specific interaction between E. Coli protein and human LDL can turn out to be useful in the future for purifying lipoproteins of a specific class and for administering plasmapheresis in patients with severe hyperlipoproteinemia.