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( Lactoferrin)
Lactoferrin (LF), also known as lactotransferrin (LTF), is a globular multifunctional protein with antimicrobial activity (bacteriocide, fungicide) and is part of the innate defense, mainly at mucoses. Lactoferrin is found in milk and many mucosal secretions such as tears and saliva. Lactoferrin is also present in secondary granules of PMN and also is secreted by some acinar cells. Lactoferrin can be purified from milk or produced recombinantly. Human colostrum has the highest concentration, followed by human milk, then cow milk. Lactoferrin belongs to the transferrin family proteins (TF, melanotransferrin, ovotransferin, etc.). Its molecular mass is 80,000 u (80 kDa). It generally contains two bound Fe+2 ions. It contains 4 identical domains, with two surrounding each iron atom. Lactoferrin antimicrobial activity is due partly to its high affinity for Fe3+ (ferric state). LF proteolysis produces lactoferricin, kaliocin-1 small peptides with antimicrobial activity. The combination of iron and lactoferrin in mucosal secretions modulate the ability and aggregation of pathogenic bacteria, and inhibit both bacteria and viruses by binding to host cells/viral particles. This inhibits the ability of bacteria and viruses to attach to cell membranes. It is also an antifungal agent. Lactoferrin receptors have been found on brush-border cells, PMN, monocytes, Mf and activated lymphocytes.
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