Journal of Bioanalysis & Biomedicine

Benchmarking Different BAMLET-like Preparations with Respect to Tryptophan Exposure, Interfacial Activity, and Effect on Cell Viability

Abstract

Hanzhen Wen, Ida M. Rundgren, Wilhelm R. Glomm and Øyvind Halskau

Human α-Lactalbumin Made Lethal to Tumors (HAMLET) or its bovine counterpart BAMLET is an α-Lactalbumin (α-LA)-oleic acid (OA) complex which induces death to tumor cells, selectively. Although HAMLET or its bovine counterpart BAMLET is prepared chromatographically, it has also been reported that HAMLET or BAMLET-like complexes can be formed by direct mixing of the two components. In this study, we prepare BAMLET-like complexes with reference to the literature, characterize and benchmark these with respect to cytotoxicity, ability to disrupt the integrity of artificial membranes, as well as spectroscopic and physicochemical properties. We show that mixing bovine α-Lactalbumin (BLA) with pure OA (liquid form), followed by incubation and shaking at 37°C is the most attractive choice for preparing BLA-OA complexes (resulting complex referred to as BLAOA (pure)). Pre-dissolving OA in methanol or ethanol and then mixing with BLA also produces a complex (referred to as BLAOA (methanol) or BLAOA (ethanol)) with similar activities as BAMLET. BLA mixed with OA pre-dispersed in phosphate buffer forms little of the active complex.