Interaction of oil bodies proteins with phospholipid bilayers: A molecular level elucidation as revealed by infrared spectroscopy.

It is crucial to develop new natural sources of emulsifiers to substitute the synthetic molecules. An ideal emulsifying system exists in plants that is consisting of oil bodies proteins and phospholipids. In this study, Fourier transformed infrared (FTIR) spectroscopy was used to investigate the interactions between oil bodies proteins (OBP) and model phospholipid (PL) membranes. The secondary structure and PL thermotropism were investigated. Different PL varying in chain length and polar head were used including two zwitterionic phospholipids, dimyristoylphosphatidylcholine and dioleoylphosphatidylcholine, and two anionic phospholipids, dimyristoylphosphatidylglycerol, dipalmitoylphosphatidylglycerol. The changes in lipid physical state and protein denaturation were investigated as a function of temperature from 20 to 80 °C. OBP in solution is composed of unordered structures and β-sheets with signs of aggregation. Anionic PL interacts with OBP whereas zwitterionic PL does not or only slightly interacts with the protein. Unsaturated PL promoted the α-helix structure in OBP. The interactions between OBP and PL depended on the protein charge inducing different protein conformations. Overall, the study showed that OBP and commercial anionic phospholipids have a potential in developing stable emulsifier for food industry.