Operando spectroscopy investigations of the redox reactions in heme and heme-proteins

• Published in: Physical chemistry chemical physics : PCCP
• Main Authors: Mandal, Subhankar, Biswakarma, Dipen, Bhattacharyya, Aninda J
• Format: Journal Article
• Language: English
• Published: England 21.10.2024
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d4cp03341h

spectroscopic investigations during molecular redox processes provide unique insights into complex molecular structures and their transformations. Herein, a combination of a potentiodynamic method with spectroscopy has been employed to holistically investigate the structural transformations during Fe-redox (Fe ↔ Fe ) of hemin vis á vis heme-proteins, myoglobin (Mb), hemoglobin (Hb) and cytochrome- (Cyt- ). The UV-vis findings reveal the formation of hemozoin (≈heme-dimer), which can be selectively prevented a high concentration of strongly interacting ligands, histidine (the fifth coordinating ligand in the heme-based protein). On the other hand, methionine does not prevent the formation of hemozoin. In Mb, Hb, and Cyt- , as the fifth coordination site is occupied by histidine, hemozoin formation is inhibited. During Fe → Fe , circular dichroism exhibits a decrease in the initial helical component in Hb from nearly 40% to 28%, which is close to the initial helix component of Mb (≈25%), strongly indicating denaturation of the protein in the redox pathway. The rate of change of the helices potential is almost identical for Mb and Hb, but comparatively faster than Cyt- . In addition, from the Raman bands of M-N dynamics and protein agglomeration, it is concluded that Cyt- prefers to agglomerate in the 2+ state, whereas Mb/Hb in the 3+ state. In this report, the power of spectroscopy is utilized to unearth the dynamics of hemin and heme-based proteins for comprehending the underlying complexities associated with the molecular redox, which have deep implications in electrocatalysis, energy storage, and sensing.