Occurrence, structure, biochemical properties and technological characteristics of lactoferrin.

The structure of the iron-binding glycoprotein lactoferrin, present in milk and other exocrine secretions, has been elucidated in great detail, both the three-dimensional protein structure and the attached N-glycans. Structure-function relationships are being established. From these studies a function for lactoferrin in host defence and modulation of iron metabolism emerges. This paper describes in some detail how iron and other cations may be bound by lactoferrins from human or bovine sources and elucidates parts of the molecule that are critical for interactions with cells and biomolecules. Furthermore, the technological aspects, more specifically the heat-sensitivity, of bovine lactoferrin in different matrices are described.

Lactoperoxidase: physico-chemical properties, occurrence, mechanism of action and applications.

Lactoperoxidase (LP) is one of the most prominent enzymes in bovine milk and catalyses the inactivation of a wide range of micro-organisms in the lactoperoxidase system (LP-s). LP-systems are also identified as natural antimicrobial systems in human secretions such as saliva, tear-fluid and milk and are found to be harmless to mammalian cells. The detailed molecular structure of LP is identified and the major products generated by the LP-s and their antimicrobial action have been elucidated for the greater part. In this paper several aspects of bovine LP and LP-s are discussed, including physico-chemical properties, occurrence in milk and colostrum and mechanisms of action. Since the introduction of industrial processes for the isolation of LP from milk and whey the interest in this enzyme has increased considerably and attention will be paid to potential and actual applications of LP-systems as biopreservatives in food and other products.

In vivo antimicrobial and antiviral activity of components in bovine milk and colostrum involved in non-specific defence.

The in vivo evidence of the antimicrobial and antiviral activity of bovine milk and colostrum derived components are reviewed with special emphasis on lactoferrin and lactoperoxidase. Their mode of action and the rationale for their application in efficacy trials with rodents, farm animals, fish and humans, to give protection against infectious agents, are described. A distinction is made between efficacy obtained by oral and non-oral administration of these non-specific defence factors which can be commercially applied in large quantities due to major achievements in dairy technology. From the in vivo studies one can infer that lactoferrin and lactoperoxidase are very promising, naturally occurring antimicrobials for use in fish farming, husbandry, oral hygiene and functional foods. Other promising milk-derived compounds include lipids, from which anti-infective degradation products are generated during digestion, and antimicrobial peptides hidden in the casein molecules.