Abstract
A cation-exchange chromatographic membrane was used for the rapid isolation of caprine and ovine lactoferrin (LF) from cheese whey. Caprine LF was isolated by one-step cation-exchange chromatography, but the isolation of ovine LF needed a further reversed-phase HPLC purification step. The antibacterial activity of these LFs, determined towards Micrococcus flavus and Escherichia coli, was compared with that of bovine LF. Of the apo-LFs the caprine protein had the highest activity. In all cases the holo-LFs showed low or negligible activity. The antibacterial properties of cationic peptides obtained by peptic hydrolysis of caprine LF were studied against E. coli and M. flavus, and the activity of these peptides was compared with that of bovine lactoferricin. In addition, the binding characteristics of bovine, ovine and caprine LF to bacterial cells of E. coli were investigated with an enzyme-linked binding assay using horseradish peroxidase-bovine LF as a conjugate. Ovine and bovine LF strongly inhibited the binding of the LF complex to the bacterial surface. The iron-free forms of these LFs showed a greater ability for binding to the bacterial cells than the iron-saturated forms. However, several cationic peptides and caprine LF did not inhibit the binding of the LF conjugate although they exhibited a marked antibacterial effect. The results of binding of the LF complex in the presence of LFs from different species and of membrane-active peptides are discussed in relation to the antibacterial activity of these proteins and peptides.
Published Version
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