title: Heteroprotein Complex Formation of Bovine Lactoferrin and Pea Protein Isolate: A Multiscale Structural Analysis.
abstract: Associative electrostatic interactions between two oppositely charged globular proteins, lactoferrin (LF) and pea protein isolate (PPI), the latter being a mixture of vicilin, legumin, and convicilin, was studied with a specific PPI/LF molar ratio at room temperature. Structural aspects of the electrostatic complexes probed at different length scales were investigated as a function of pH by means of different complementary techniques, namely, with dynamic light scattering, small-angle X-ray scattering (SAXS), turbidity measurements, and atomic force microscopy (AFM). Irrespective of the applied techniques, the results consistently displayed that complexation between LF and PPI did occur. In an optimum narrow range of pH 5.0-5.8, a viscous liquid phase of complex coacervate was obtained upon mild centrifugation of the turbid LF-PPI mixture with a maximum Rh, turbidity and the ζ-potential being close to zero observed at pH 5.4. In particular, the SAXS data demonstrated that the coacervates were densely assembled with a roughly spherical size distribution exhibiting a maximum extension of ∼80 nm at pH 5.4. Equally, AFM image analysis showed size distributions containing most frequent cluster sizes around 40-80 nm with spherical to elliptical shapes (axis aspect ratio ≤ 2) as well as less frequent elongated to chainlike structures. The most frequently observed compact complexes, we identify as mainly leading to LF-PPI coacervation, whereas for the less frequent chain-like aggregates, we hypothesize that additionally PPI-PPI facilitated complexes exist.
authors.affiliation: Food Colloids and Processing Group, School of Food Science and Nutrition, University of Leeds , Leeds LS2 9JT, United Kingdom.|Food Engineering Department, Gaziantep University , 27310 Gaziantep, Turkey.
authors.forename: Eda
authors.initials: E
authors.lastname: Adal
authors.affiliation: Food Colloids and Processing Group, School of Food Science and Nutrition, University of Leeds , Leeds LS2 9JT, United Kingdom.
authors.forename: Amin
authors.initials: A
authors.lastname: Sadeghpour
authors.affiliation: Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds , Leeds LS2 9JT, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Connell
authors.affiliation: Food Colloids and Processing Group, School of Food Science and Nutrition, University of Leeds , Leeds LS2 9JT, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Rappolt
authors.affiliation: Food Engineering Department, Gaziantep University , 27310 Gaziantep, Turkey.
authors.forename: Esra
authors.initials: E
authors.lastname: Ibanoglu
authors.affiliation: Food Colloids and Processing Group, School of Food Science and Nutrition, University of Leeds , Leeds LS2 9JT, United Kingdom.
authors.forename: Anwesha
authors.identifier: 0000-0003-1742-2122
authors.initials: A
authors.lastname: Sarkar
mesh_terms: D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D007781:Lactoferrin / Q000737:chemistry* / Q000378:metabolism; D018625:Microscopy, Atomic Force; D018532:Pisum sativum / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D053838:Scattering, Small Angle; D055672:Static Electricity; D014961:X-Ray Diffraction
chemical_list: D010940:Plant Proteins; D007781:Lactoferrin