Curious Results in the Prospective Binding Interactions of the Food Additive Tartrazine with β-Lactoglobulin

Abstract

The detailed characterizations of the binding interactions between food additive tartrazine (TZ) and β-lactoglobulin (β-LG) have been investigated through spectroscopic techniques combined with a molecular modeling study. A series of analyses, such as hyperchromic change in the UV–visible spectra, temperature-dependent quenching constant, time-resolved fluorescence, and Rayleigh scattering measurements, show that quenching of β-LG proceeds by a static quenching mechanism. TZ specifically binds with β-LG in a stoichiometry ratio of 1:1, and the observed binding constants (104, K) are 7.64, 9.13, 9.72, and 10.79 at 293, 298, 303, and 308 K, respectively. However, the curious results of binding constants (K) with temperature, encountered in the static quenching, have been well explained on the basis of Le Chatelier’s principle. Thermodynamic data and pH-dependent studies along with the surface hydrophobicity binding displacement assay reveal that the durable mode of binding is chiefly entropy-driven, revealing noteworthy interactions of such ionic molecules with the hydrophobic part of β-LG. The modulation of protein conformation has been investigated through steady-state absorption spectroscopy, synchronous emission spectroscopy, circular dichroism, and dynamic light scattering studies. TZ acts as a potential inhibitor in fibrillogenesis. Furthermore, the molecular docking study offers accurate insights about the binding of TZ with β-LG, in consistence with the experimental results. This study would be helpful in pharmaceutical, food, and industrial engineering chemistry research.

Enhanced Physicochemical Stability of β-Carotene Emulsions Stabilized by β-Lactoglobulin−Ferulic Acid−Chitosan Ternary Conjugate

“…In the aliphatic region (3.0–4.5 ppm), the change of multiple peaks indicated that CFC was probably bound with aliphatic residues containing polar head groups (−OCH 3 , −NH 3 + , etc.) of β-LG via noncovalent interaction. , Compared with β-LG and BFCM, BFCC showed obvious changes of aromatic and aliphatic regions because of the covalent interaction between CFC and β-LG. Also, the disappearance of proton signals at 3.73–7.49 ppm (H of feruloyl groups) indicated the covalent conjugation between feruloyl groups of CFC and free amino groups of β-LG.…”

“…The difference in chemical shift between β-LG and BFCM was used to investigate the noncovalent interaction between CFC and β-LG. An apparent downfield shift was observed in the aromatic region of 1 H NMR spectra because of the noncovalent interaction, which probably induced the microenvironmental transformation of the aromatic residues of β-LG . In the aliphatic region (3.0–4.5 ppm), the change of multiple peaks indicated that CFC was probably bound with aliphatic residues containing polar head groups (−OCH 3 , −NH 3 + , etc.)…”

“…of β-LG via noncovalent interaction. 24,25 Compared with β-LG and BFCM, BFCC showed obvious changes of aromatic and aliphatic regions because of the covalent interaction between CFC and β-LG. Also, the disappearance of proton signals at 3.73−7.49 ppm (H of feruloyl groups) indicated the covalent conjugation between feruloyl groups of CFC and free amino groups of β-LG.…”

New ligand-binding sites identified in the crystal structures of β-lactoglobulin complexes with desipramine

“…BLG can also interact with various drugs and therefore has been proposed as a potential carrier for many therapeutic agents (Gholami et al, 2021;Ghalandari et al, 2015;Balasco et al, 2020;Kayani et al, 2018). Like most lipocalins, the -lactoglobulin molecule folds as an eight-stranded -barrel, which is the primary ligand-binding site (Allahdad et al, 2020;Dan et al, 2019;Loch et al, 2011Loch et al, , 2012Loch et al, , 2013Loch et al, , 2015Loch et al, , 2018Sawyer, 2013;Patel et al, 2019).…”

Follow the Hygienic Standard of Food Additives in Develop and Produce Nutritive Dairy Products

“…With the continuous improvement of living standards, people have higher and higher requirements on the quality of food, which requires both delicacy and safety. Due to the continuous progress and development of biotechnology, the types of food additives are increasing, and the scope of their application in food production is also expanding [1][2]. The use of food additives has both advantages and disadvantages.…”