Tailoring ternary complexes of lactoferrin, EGCG, and α-lactalbumin by assembly sequence strategies: Structural characterization, assembly mechanism, and emulsification elucidation

Yangyang Jia; Ziying Yang; Linshuang Xu; Ibrahim Khalifa; Lanlan Hu; Yuanyang Nie; Bo Li; Benguo Liu; Wei Yang

doi:10.1016/j.foodchem.2024.142047

Tailoring ternary complexes of lactoferrin, EGCG, and α-lactalbumin by assembly sequence strategies: Structural characterization, assembly mechanism, and emulsification elucidation

Food Chem. 2024 Nov 16;465(Pt 2):142047. doi: 10.1016/j.foodchem.2024.142047. Online ahead of print.

Authors

Yangyang Jia¹, Ziying Yang¹, Linshuang Xu¹, Ibrahim Khalifa², Lanlan Hu¹, Yuanyang Nie¹, Bo Li¹, Benguo Liu¹, Wei Yang³

Affiliations

¹ School of Food Science, Henan Institute of Science and Technology, Xinxiang 453000, China.
² Food Technology Department, Faculty of Agriculture, Benha University, Moshtohor, 13736, Egypt.
³ School of Food Science, Henan Institute of Science and Technology, Xinxiang 453000, China.. Electronic address: Shipinmeili@163.com.

PMID: 39579400
DOI: 10.1016/j.foodchem.2024.142047

Abstract

Three distinct ternary complexes (TC-M1, TC-M2, and TC-M3) based on lactoferrin (LF), (-)-epigallocatechin-3-gallate (EGCG), and α-lactalbumin (ALA) were prepared by varying the assembly sequence and EGCG concentrations (ranging from 0 to 2.0 mM). Structural characterization was performed using various spectroscopic techniques, while the assembly mechanisms were investigated through ITC and molecular docking. These ternary complexes were further evaluated as stabilizers in Pickering emulsions. Nephelometry and DLS analysis showed that TC-M1 exhibited the highest turbidity and largest particle size, followed by TC-M2 and TC-M3. FT-IR and fluorescence spectroscopy revealed strong binding between EGCG and both ALA and LF, enhancing the hydrophilicity and extending structure of proteins. ITC and molecular docking studies indicated spontaneous interactions primarily driven by hydrogen bonding and hydrophobic forces, with LF (Ka1 = 1.9 × 10⁵ M^-1) and ALA (Ka1 = 3.6 × 10⁴ M^-1) binding approximately 3.3 and 2.9 EGCG molecules, respectively. Pickering emulsions formed by these complexes demonstrated superior emulsification properties, with TC-M1 showing the smallest CI (10.09 % ± 0.19 %), particle size (1 to 2 μm), and higher MVI (1.2) and EI (2.5) at 2.0 mM EGCG, outperforming TC-M2 and TC-M3 in stability. Overall, the assembly sequence of LF, ALA, and EGCG, along with EGCG concentration, lays the foundation for designing protein-polyphenol-protein ternary complexes, offering enhanced stability and functionality for diverse EGCG delivery applications.

Keywords: Assembly sequence; Binding mechanism; Emulsification characteristics; Structural characterization; Ternary complex.