Lipopolysaccharide interaction with lysozyme: Binding of lipopolysaccharide to lysozyme and inhibition of lysozyme enzymatic activity.

Abstract

Experiments have been carried out to characterize the binding of lysozyme (LZM) to bacteriol lipopolysaccharide (LPS). The formation of LPS·LZM complexes can be readily demonstrated using either physical-chemical separation techniques or a radiolabeled photoaffinity LPS probe. The binding affinity of LZM for LPS has been estimated to be ∼ 108 liters/mol. Binding of LPS results in loss of LZM enzymatic activity by a noncompetitive inhibition, as assessed by either particulate or soluble substrates. This interaction of LPS with LZM is dictated primarily by hydrophobic interactions and appears to be a general property of both constituents. Binding can be demonstrated with LZM of both human and avian sources, as well as with LPS isolated from a variety of Gram-negative organisms. The addition of LPS to biologically relevant fluids containing LZM results in dose-dependent inhibition of LZM enzymatic activity suggesting that such interactions may have relevance in Gram-negative infections. Finally LZM has been shown to reduce the endotoxic activity of LPS as assessed by gelation of Limulus amoebocyte lysates.