Elucidation on the interaction between transferrin and ascorbic acid: A study based on spectroscopic analysis, molecular docking technology, and antioxidant evaluation

Abstract

Ascorbic acid (Vitamin C, VC) is widely used in the food industry due to its antioxidant and neuroprotective ability. Transferrin (TRF) is a carrier protein in blood which plays crucial roles in maintaining iron homeostasis. In this study, the interaction between VC and TRF was investigated in vitro by using multi-spectroscopy, molecular docking technology, and antioxidant evaluation for the first time. According to the results of spectroscopy, TRF and VC formed a complex and the binding constant (Ka) was 1.095 ± 0.021 × 104 M−1 at 298 K. The thermodynamic parameters (ΔH and ΔS) were all negative, suggesting that the main interaction forces were hydrogen bonds and van der Waals force. Moreover, VC bound to TRF altered the secondary structure of TRF with a reduction in α-helix and an increment in β-sheet. Molecular docking manifested that after entering the cavity of TRF, the hydroxyl groups (OH) of VC formed five hydrogen bonds with amino acid residues of TRF. Additionally, binding with TRF enhanced the scavenging capacity of VC on superoxide anion radicals in low-concentration, while the scavenging ability of VC against DPPH radicals was inhibited after generating a complex.