Biophysical Investigation of the Binding Features of Qurcetin and Beta-Carotene Flovonoids with Bovine Haemoglobin

Abstract

Bovine haemoglobin (BHb) is quite well for the role as an oxidizer in the vascular system of animals. It also helps to transport carbon dioxide and maintains blood pH, both directly and indirectly. It removes hydrogen ions in the capillaries and carries them to the lungs. In addition, it is involved in many clinical diseases such as leukemia, anemia, heart disease, excessive loss of blood, etc. The displacement reaction of ligands from their associated proteins is the primary mechanism for particular medication. Because interactions between bio-macromolecules and medicines can cause changes in protein structure, spectroscopic and molecular dynamic modelling techniques were used in this work. The displacing of ligands from their receptors was calculated using binary and ternary systems' quenching and dissociation characteristics. Multi-spectroscopic and computational (molecular docking) investigations were used to study the interaction of two bioactive flavonoids, quercetin and Beta-carotene, with bovine haemoglobin (BHb). Through a fluorescence quenching mechanism, the two flavonoids were reported to quench the intrinsic fluorescence of BHb. The binding constants at different concentration were observed to be (14.023±0.73) × 10⁴ M^-1 and (7.848±0.20) × 10⁴ M^-1, respectively for quercetin and Betacarotene binding with BHb. Both rutin and quercetin were observed to increase the polarity around the Trp residues of BHb as indicated by synchronous spectral studies. The binding of the flavonoids induced no substantial changes in the secondary engineering structures of the protein, as shown by FTIR spectra. The flavonoids engage at the 2-Trp37 residue of BHb, as per fluorescence experiments. Excellent correlations with the experimental studies were observed from the molecular docking studies.