Structure-Redox Response Correlation in a Few Select Heme Systems Using X-ray Absorption Spectroelectrochemistry

Abstract

Heme based biomolecules control some of the most crucial life processes, such as oxygen and electron transport during respiration and energy metabolism, respectively. The active site of the heme, viz., the metal center, plays a key role and attributes functionality to these biomolecules. During the oxygen binding and debinding processes, it is important to note that the oxidation state of iron in hemoglobin (+II in the native form) does not undergo any change. However, the spin states of the metal center change. We present here a comprehensive study of the redox response of such molecules, based on the electronic structure of the active site. The local electronic structure of heme in a few selective molecular systems is studied in operando via synchrotron Xray absorption spectroscopy (Fe K-edge) and cyclic voltammetry. Our objective is to identify the electronic structural parameters that can effectively be correlated with the redox reversibility. Evolution in these parameters can be followed to trace the overall changes in redox state of the system. Our data indicate that axial coordination and spin state of the iron center are two such parameters that are intimately connected with the redox response.

Enzymatic X-ray absorption spectroelectrochemistry

“…In another study, Bhattacharyya et al , 76 reported operando XAS of heme-based biomolecules. They performed Fe K-edge XAS studies in homogenous conditions under electrochemical control simultaneously measuring cyclic voltammetry.…”

Comparative analysis of the interaction of allure red with hemoglobin and myoglobin

“…Hemoglobin (Hb) and myoglobin (Mb) are the main color-forming proteins in animal meat. Hb is mainly found in blood and is responsible for carrying oxygen and participating in redox reactions in living organisms (Samajdar and Bhattacharyya 2021). Hb is composed of four subunits, each of which is composed of peptide chains and heme molecules, and Hb is oxidized to methylated hemoglobin during the processing and storage of meat.…”