Features of the complex of food additive hesperidin to hemoglobin

The purpose of the current work was to examine the complexation of a mammalian protein, hemoglobin (Hb) with a food additive hesperidin at physiological conditions. Molecular modeling, fluorescence, and circular dichroism (CD) methods were exploited to analyze the binding domain, affinity, and the effects of hesperidin conjugation on Hb spatial structure. From molecular modeling, central cavity of Hb was assigned to retain high-affinity for hesperidin, this corroborates the steady state fluorescence and hydrophobic ANS probe results. The association of hesperidin with Hb emerges fluorescence quenching via static type, this phenomenon display that the ground state complex formation with an affinity of 104 M−1, and hypsochromic effect transpires. Additionally, the alterations of synchronous fluorescence, CD, and three-dimensional fluorescence suggest that the polypeptide chain of Hb partially folding after conjugation with hesperidin. The above data suggest that Hb plays a significant role in the plasma distribution and transportation of hesperidin and related dietary flavonoids.

Hesperidin situates within the central cavity of Hb, as well as the amino acid residues, such as Tyr-35, Trp-37, Pro-95, Phe-98, Lys-99, Glu-101, and Asp-126, which all keep an appropriate distance involved in making hydrogen bonds, π–π, and electrostatic interactions with hesperidin, this conjugation arouses faint folding of the polypeptide chain of protein, ascends the hydrophobicity and leads to structural changes.Figure optionsDownload as PowerPoint slideHighlights
► Central cavity of Hb is designated to possess high-affinity for hesperidin.
► Static type is dominance for the reduction in the β-37 Trp residue fluorescence.
► Hydrogen bond, π–π, and electrostatic interaction exist between Hb and hesperidin.
► Hb structure folds upon complex with hesperidin.
► Our task disclose flavonoids absorption, bioavailability, and biological activity.