Binding characteristics of bovine lactoferrin to the cell surface of Clostridium species and identification of the lactoferrin-binding protein.

The binding characteristics of bovine lactoferrin (bLf) to cells of the Clostridium species were observed by using a horseradish peroxidase-bLf conjugate. A bLf-binding protein (BP) having a relative molecular mass of about 33 kDa was confirmed in the surface layer components from 7 strains of the Clostridium species. The binding of the conjugate to bLf-BP or C. perfringens was strongly blocked by intact Lfs, lysine or arginine residues modified bLf, and deglycosylated bLf, but was not by other milk proteins or by the constituent sugars of glycan. Bacterial growth was inhibited by bLf, but was slightly inhibited by lysine residues modified bLf or deglycosylated bLf. Lactoferricin B did not block the binding of the conjugate, but strongly inhibited the bacterial growth. This suggests that the lysine or arginine residues and glycan of bLf hardly participated in binding bLf to the bacterial cells, but that the amino acid residues and glycan played an important role in inhibiting the growth of bacteria.