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Updated: Aug 17, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Binding of porphyrin to horseradish peroxidase: effects on structure and function
Susmita Sil1, Abhay Sankar Chakraborti
1Department of Biophysics, Molecular Biology & Genetics, University College of Science, University of Calcutta, 92, Acharyya Prafulla Chandra Road, Kolkata 700009, India.
Abstract:
Spectrofluorimetric and spectrophotometric studies were done to understand the binding of hematoporphyrin, a photosensitizer to horseradish peroxidase (EC1.11.1.7). The binding affinity constant (K) decreases as the state of aggregation of the porphyrin increases, while the number of binding sites (approximately 1) remains unchanged. The interaction appears to be mostly hydrophobic, entropy-driven and endothermic process. Hematoporphyrin potentiates horseradish peroxidase-catalyzed H2O2-mediated NADH oxidation, probably by porphyrin-influenced removal of superoxide radicals, which are generated in the system. Conformational change of the protein due to its interaction with porphyrin may be associated with potentiation of the catalytic activity of the enzyme.
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