Lactoferrin Structure-Function Relationships

作者：Jeremy H. Brock · 发表于：Humana Press eBooks · 年份：1997 · DOI：10.1007/978-1-4612-3956-7_1 · 被引用次数：16 · 研究领域：Infant Nutrition and Health、Pediatric Hepatobiliary Diseases and Treatments、Neonatal Respiratory Health Research

Although lactoferrin was first isolated over 30 years ago, its function remains unclear. Structurally, it closely resembles the iron-transport protein transferrin, suggesting that lactoferrin may also have an iron-transport role, and lactoferrin-binding sites or receptors have been reported on a variety of cells and tissues. However, the high pI of lactoferrin (~8.5–9.0) allows it to interact with many macromolecules, which makes identification of genuine receptors difficult. The idea that lactoferrin in breast milk acts as a specific transporter of iron to the mucosal cells of the infant gut could explain the high bioavailability of breast milk iron, but good evidence for this is lacking, and there are indications that lactoferrin may actually inhibit iron absorption. Another possible function is as an antimicrobial agent, particularly in the infant gut, and also at inflammatory foci where lactoferrin is released by degran-ulating neutrophils. There is ample in vitro evidence that lactoferrin exerts a bacteriostatic effect through its ability to sequester iron, and more recently, a bactericidal activity that is independent of iron-binding and mediated through an N-terminal basic peptide has been reported. However, there are disappointingly few in vivo data in support of the antimicrobial hypothesis. Lactoferrin is also reported to have various effects on the immune system, such as regulation of antibody production, complement activation, and natural killer (NK) cell function...