Molecular Interaction of Pea Glutelin and Lipophilic Bioactive Compounds: Structure-Binding Relationship and Nano-/Microcomplexation.

This study investigated the impact of ionic strength and lipophilicity of bioactive compounds on their interaction with the alkaline soluble pea glutelin fraction (ASF) using the fluorescence quenching technique. A Stern-Volmer quenching constant, K D , of 8.9 ± 0.10, 5.3 ± 0.06, 4.0 ± 0.01, 1.1 ± 0.00, 0.9 ± 0.02, and 0.1 ± 0.00 (×10 4 M -1 ) was observed for curcumin-ASF (CuASF), astaxanthin-ASF (AsASF), cholecalciferol-ASF (ChASF), β-carotene-ASF (βCaASF), coenzyme Q 10 -ASF (Q 10 ASF), and β-sitosterol-ASF (βSiASF) complexes, respectively. An increase in ionic strength did not significantly change K D , the effective quenching constant K , and the bimolecular quenching rate constant K Q . However, it changed the mode of interaction of the ASF with cholecalciferol, β-carotene, coenzyme Q 10 , and β-sitosterol from static to static-dynamic quenching. Transmission electron microscopy showed that the morphology formed with protein (spherical nanocomplexes, microaggregates, or fiber-like particles) differed among the compounds. The favorable binding of CuASF, AsASF, ChASF, and βCaASF complexes provides stable matrices for formulating protein-based delivery systems for lipophilic nutraceuticals.