Structure and Stability Analysis of Cytotoxic Complex of Camel α-Lactalbumin and Unsaturated Fatty Acids Produced at High Temperature

Abstract

α-Lactalbumin α-La), together with oleic acid can be converted to a complex, which kills tumor cells selectively. Cytotoxic α-La -oleic acid and α-La -linoleic acid complexes were generated by adding fatty acid to camel holo α-La at 60 ° C (referred to as La-OA-60 and La-LA-60 state, respectively). Structural properties of these complexes were studied and compared to the camel α-La. The experimental results show that linoleic acid induces α-La partial unfolding but oleic acid does not change the protein structure significantly. Also the stability of La-OA-60 and La-LA-60 toward thermal denaturation was measured. The order of temperature at the transition midpoint is as follows: La-LA-60 < La-OA-60 < α-La. La-OA-60 complex inhibited tubulin polymerization in vitro. Although the structures of La-OA-60 and La-LA-60 were different, these two complexes had similar cytotoxic effect to DU145 human prostate cancer cells. Samples of La-OA-60 that have been renatured after denaturation lost the specific biological activity toward tumor cells.

Self-assembled β-lactoglobulin–oleic acid and β-lactoglobulin–linoleic acid complexes with antitumor activities

“…α-Lactalbumin also binds oleic acid (OA), with the resulting complex exhibiting cytotoxic activity toward tumor cells Atri et al, 2011;Fang et al, 2012). It is noteworthy that this function has been observed in α-LA proteins of several different species (Pettersson et al, 2006;Atri et al, 2011), as well as in fragments of α-LA (Tolin et al, 2010) and proteins capable of assembling to α-LA, such as lysozymes (Vukojević et al, 2010). Although little evidence is available to support the idea that α-LA belongs to the lipocalin family of proteins, its 3-dimensional structure shares several similarities with β-LG, especially its triple-stranded anti-parallel β-sheets (Pettersson et al, 2006).…”

Effects of pH and protein conformation on in-solution complexation between bovine α-lactalbumin and oleic acid: Binding trend analysis by using SPR and ITC

“…This 'in-column' complexation is believed to exploit the hydrophobic interaction between the hydrophobic domains of apo-α-LA in the fluid phase and the fatty acid's lipophilic tails in the stationary phase [13][14]; however, the exact complexation mechanism has not been fully elucidated. Additionally, HAMLET can be synthesized by titrating an oleic acid solution into a solution of apo-α-LA, i.e., 'in-solution' complexation [15].…”

Therapeutic Applications of Camel’s Milk and Urine against Cancer: Current Development Efforts and Future Perspectives

“…Their extraordinary stability is attributable to efficient refolding after chemical or thermal denaturation and increased resistance against denaturation [138]. At high temperature (60°C), camel milk α-lactalbumin and its complexes combined with oleic acid and linoleic acid can have a stable structure, and exhibit a cytotoxic effect on a human prostate cancer cell even after exposure to such temperature [138]. It is known that camels Lactoferrin (cLF) possess supreme immunoregulatory and anti-cancer effect.…”