Effect of chemical modification on anti-microbial and anti-viral properties of milk proteins

Milk proteins not only supply nutrients to the neonate, they also possess a variety of biological properties. Among these proteins, lactoferrin (LF), a component of bovine milk and colostrums, has been widely studied for its biological activity, including antimicrobial properties and interference with viral infections. Net charge appears to play an important role in LF anti-microbial and anti-viral activity. Hence, investigations have been undertaken to employ chemical modifications (amidation and acylation) to change the net charges on the protein. Amidation has also been applied to P-lactoglobulin (beta-Lg). It has been shown that amidation substantially enhanced anti-microbial activity of LF and beta-Lg against a range of Gram-positive and Gram-negative bacteria, including the major food spoilage bacterium Pseudomonas fluorescens. However, acylation of LF eliminated its anti-microbial and anti-viral activities (against poliovirus and feline calicivirus, a surrogate for non-culturable noroviruses).