6533b82efe1ef96bd12939a3

RESEARCH PRODUCT

Interactions entre la beta-lactoglobuline et les arômes : impact au niveau moléculaire

subject

description

Interactions between β-lactoglobulin (BLG) and aroma compounds were investigated by complementary techniques for a better knowledge of binding mechanisms between proteins and aroma compounds at a molecular scale. Two binding sites have been defined for the monomeric BLG, one internal site within the central calyx, and one external site between the calyx and the α helix. In a first step, a relation between the ligand structure and its binding behaviour was established from the study of impact of a wide range of aroma compounds on the structure of native BLG. We evidenced at least two binding behaviours as a function of the chemical class, the hydrophobicity, or the structure of the ligands. The key residues involved in aroma compound binding were identified. On the one hand, the internal site of BLG accommodates the elongated aroma compounds. On the other hand, the external site of BLG fits the aroma compounds which have or can adopt a compact structure by folding. Then, the investigation of the interactions between BLG and two aroma compounds allowed to get insights into competition phenomena between aroma compounds. Aroma compounds can compete for binding to common sites. Besides, the accommodation of a first ligand can hinder the binding of a second ligand through a negative cooperative phenomenon. In a second step, we investigated the impact of a thermal treatment (1h for 80°C) on BLG structure at acidic pH (pH<3) and their interactions with aroma compounds. The thermal treatment induces the conversion of the native BLG into a stable molten globule state. The protein unfolds partially upon preheating which modulates the access to the calyx and makes easier BLG-aroma compounds interactions, in particular within the internal site.