Structure and Dynamics of Heteroprotein Coacervates

P.D.S. Peixoto (1) , G.M. Tavares (1) , Thomas Croguennec (1) , Aurélie Nicolas (1) , P. Hamon (1) , Claire Roiland (2) , Said Bouhallab (1)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 ISCR - Institut des Sciences Chimiques de Rennes

Under specific conditions, mixing two oppositely charged proteins induces liquid−liquid phase separation. The denser phase, or coacervate phase, can be potentially applied as a system to protect or encapsulate different bioactive molecules with a broad range of food and/or medical applications. The optimization of the design and efficiency of such systems requires a precise understanding of the structure and the equilibrium of the nanocomplexes formed within the coacervate. Here, we report on the nanocomplexes and the dynamics of the coacervates formed by two well-known, oppositely charged proteins β-lactoglobulin (β-LG, pI ≈ 5.2) and lactoferrin (LF, pI ≈ 8.5). Fluorescence recovery after photobleaching (FRAP) and solid-state nuclear magnetic resonance (NMR) experiments indicate the coexistence of several nanocomplexes as the primary units for the coacervation. To our knowledge, this is the first evidence of the occurrence of an equilibrium between quite unstable nanocomplexes in the coacervate phase. Combined with in silico docking experiments, these data support the fact that coacervation in the present heteroprotein system depends not only on the structural composition of the coacervates but also on the association rates of the proteins forming the nanocomplexes.

Mots clés: Proteins; Association rates; Structure and dynamics; Nuclear magnetic resonance; Liquid-liquid phase separation; Phase separation; Structural composition; Solid-state nuclear magnetic resonance; Medical applications; Photobleaching; Bioactive molecules; Beta-lactoglobulin; Fluorescence recovery after photobleaching

Domaines: Chimie; Ingénierie des aliments

P.D.S. Peixoto, G.M. Tavares, Thomas Croguennec, Aurélie Nicolas, P. Hamon, et al.. Structure and Dynamics of Heteroprotein Coacervates. Langmuir, 2016, 32 (31), pp.7821-7828. ⟨10.1021/acs.langmuir.6b01015⟩. ⟨hal-01367243⟩