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

The alpha-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 alpha-lactalbumin from bovine milk and human milk alpha-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 alpha-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. (C) 2018 Elsevier Ltd. All rights reserved.