Energetic and molecular dynamic characterization of lysozyme/β-carotene interaction

Abstract

β-Carotene () is a pro-vitamin A carotenoid with powerful antioxidant properties. However, it has low aqueous solubility, light and heat stability, and bioavailability. An interesting strategy to improve incorporation in food matrices while preserving its properties is the use of proteins as nanocarriers. Lysozyme () is a protein capable of carrying bioactive molecules and has antitumor, antiviral, and antimicrobial activities. To enable the use of with , it is important to understand the dynamics of binding. Here, a thermodynamic and kinetic investigation of complex formation at physiological pH was carried out using fluorescence spectroscopy (FS), differential scanning nanocalorimetry (nanoDSC), molecular docking, and surface plasmon resonance (SPR). The binding constants were found to be on the order of 105 to 103 L mol−1 by FS and SPR, respectively, revealing that the interaction between and is entropically driven. In addition, kinetic parameters related to intermediate complex formation were obtained, and we found that the rate of intermediate complex formation was higher on the free molecules association than on the dissociation based on the lower values than . In addition, the occurrence of an isokinetic relationship indicates that intermediate complex formation results in changes in binding sites, and both desolvation of the free molecules and conformational changes are temperature dependent. Thus, we have elucidated the dynamics of complex formation and provided important evidence that can be used to carry , which will improve its application and functionality in food.