Interaction mechanism between zein and β-lactoglobulin: Insights from multi-spectroscopy and molecular dynamics simulation methods

The interaction of zein and beta-lactoglobulin (beta-LG) was explored by experiments combined with molecular dynamics simulation method. The results showed that the particle sizes of beta-LG-Zein complex nanoparticles enhanced from 69.5 nm to 153.5 nm when the beta-LG/zein mass ratio changed from 9:1 to 2:8. The complex nanoparticles exhibited better stability after 30 d of storage. Transmission electron microscope (TEM) showed that the beta-LG-Zein nanoparticles dispersed evenly with high beta-LG concentration. Fourier transform infrared spectroscopy (FTIR) and dissociation test experiments elucidated that hydrogen bonding, hydrophobic and electrostatic interactions were important for preparing beta-LG-Zein complex nanoparticles. The conformational model of zein was constructed through homology modeling, and the structure of beta-LG-Zein complex was obtained via molecular docking. Molecular dynamics simulation (MD) results clarified that beta-LG firmly grasped zein like a clamp, taking the P68 and G88 residues of zein as the supporting point, and the binding Gibbs free energy reached -39.81 kcal/mol. In addition, the residues of V64, P65, P68, I69, G74, G75, G77 and G88 in zein and the residues of P54, L103 and A104 in beta-LG played critical roles for the binding of zein to beta-LG. This work can provide a theoretical foundation for the applications of beta-LG-Zein complexes in food industry.