Biophysical Characterization of Genistein in Its Natural Carrier Human Hemoglobin Using Spectroscopic and Computational Approaches

Abstract

<p> Steady state and time resolved fluorescence spectroscopy, combined with molecular dynamics simulation, have been used to explore the interactions of a therapeutically important bioflavonoid, genistein, with normal human hemoglobin (HbA). Binding constants estimated from the fluorescence studies were K = (3.5 ± 0.32) <span style="font-family:'Times New Roman','serif';font-size:10pt;">×</span>10⁴M^-¹ for genistein. Specific interactions with HbA were confirmed from flavonoid-induced fluorescence quenching of the tryptophan in the protein HbA. The mechanism of this quenching involves both static and dynamic components as indicated by: (a) increase in the values of Stern-Volmer quenching constants with temperatures, (b) <img alt="" src="Edit_47df3b02-567a-42e7-bd74-98828ac3d0ab.png" />/ <img alt="" src="Edit_e1864809-1218-4539-87fa-88b01125bf8f.png" />is slightly > 1 (where <img alt="" src="Edit_a90614f2-0cd9-4a74-9ac3-b13eaaf93082.png" /> and <img alt="" src="Edit_da22a650-b4f6-4e4a-a12e-8594a390ef3d.png" />are the unquenched and quenched tryptophan fluorescence lifetimes (averaged) respectively). Molecular docking and dynamic simulations reveal that genistein binds between the subunits of HbA, ~18 ? away from the closest heme group of chain <i><span style="font-family:'Times New Roman','serif';font-size:10pt;">α</span></i>1, emphasizing the fact that the drug does not interfere with oxygen binding site of HbA. </p

Inhibitory mechanisms of polyphenols on heme protein-mediated lipid oxidation in muscle food: New insights and advances

“…In addition, the authors argued that direct electron transfer between the bound quercetin and the heme irons of hemoglobin was unlikely due to the distance between the two moieties. In contrast, the isoflavone genistein was predicted to localize between the subunits of human hemoglobin, which is 18 angstroms away from the heme cavity, without disturbing the structural integrity of the protein (Pahari et al 2013).…”

“…The basis of non-covalent interactions generally relies on combinations of hydrogen bonding, Van der Waals interaction, electrostatic interaction, and hydrophobic interactions between functional groups of polyphenols and proteins (Chakraborty et al 2012;Pahari et al 2013). Polyphenol structures typically contain hydroxyl, carbonyl, and carboxylic groups that can form hydrogen bonding with polar groups of the protein backbone and side chains, particularly the positively-charged ones (Chakraborty et al 2012).…”

“…Meanwhile, the hydrophobic pockets of protein can accommodate the less hydrophilic near-planar structure of polyphenols, which strengthens the binding (Das et al 2020;Xiao et al 2011). The binding of polyphenols on the structure of heme protein can be monitored via spectroscopic techniques due to the fluorescence quenching effect of the bound phenol groups (Chakraborty et al 2012;Das et al 2020;Pahari et al 2013;Xiao et al 2011).…”

Molecular investigation of the interaction between ionic liquid type gemini surfactant and lysozyme: A spectroscopic and computational approach

“…To 71 In addition, the R g values were also measured for overall structural dimension of the protein. 72 The calculated R g values for free lysozyme and the lyosozyme-[C 12 24-C 12 im]Br 2 complex were found to be 1.3436 nm and 1.3493 nm, respectively and presented in Figure 9B. The R g values for free and bound lysozyme are highly closer to each other, suggesting that there is no such structural unfolding is induced by [C 12 24-C 12 im]Br 2 after binding with the protein 72 Therefore, to confirm the actual conformational change in lysozyme the solvent accessible surface area (SASA) variation in the time interval of 4000 ps in presence and absence of [C 12 24-C 12 im]Br 2 were analyzed and is shown in Figure 10A.…”