Binding of α-lactalbumin to oleic acid monolayer and its relevance to formation of HAMLET-like complexes

Abstract

The α-lactalbumin from human milk forms a cytotoxic protein-fatty acid complex with oleic acid (OA) called HAMLET, which is probably formed in the stomach of a breastfed infant. However, the mechanism of this process is still unclear and in vivo synthesis of this tumoricidal complex has not yet been observed. We used a Langmuir monolayer approach to form an OA monolayer and study the interactions between this fatty acid and milk proteins. The results revealed irreversible adsorption of α-lactalbumin from bovine milk and human milk α-lactalbumin followed by the penetration of the OA monolayer. The process was found to be governed mainly by hydrophobic interactions between protein and the fatty acid. Binding of OA and α-lactalbumin led to the formation of a stable interfacial film that was recognisable as a HAMLET-like complex. These results give credence to the concept of HAMLET formation in a newborn's gastrointestinal system.