PMID- 37480762 OWN - NLM STAT- MEDLINE DCOM- 20230822 LR - 20230822 IS - 1873-3344 (Electronic) IS - 0162-0134 (Linking) VI - 247 DP - 2023 Oct TI - Comparative study of the binding and activation of 2,4-dichlorophenol by dehaloperoxidase A and B. PG - 112332 LID - S0162-0134(23)00214-3 [pii] LID - 10.1016/j.jinorgbio.2023.112332 [doi] AB - The dehaloperoxidase-hemoglobin (DHP), first isolated from the coelom of a marine terebellid polychaete, Amphitrite ornata, is an example of a multi-functional heme enzyme. Long known for its reversible oxygen (O(2)) binding, further studies have established DHP activity as a peroxidase, oxidase, oxygenase, and peroxygenase. The specific reactivity depends on substrate binding at various internal and external binding sites. This study focuses on comparison of the binding and reactivity of the substrate 2,4-dichlorophenol (DCP) in the isoforms DHPA and B. There is strong interest in the degradation of DCP because of its wide use in the chemical industry, presence in waste streams, and particular reactivity to form dioxins, some of the most toxic compounds known. The catalytic efficiency is 3.5 times higher for DCP oxidation in DHPB than DHPA by a peroxidase mechanism. However, DHPA and B both show self-inhibition even at modest concentrations of DCP. This phenomenon is analogous to the self-inhibition of 2,4,6-trichlorophenol (TCP) at higher concentration. The activation energies of the electron transfer steps in DCP in DHPA and DHPB are 19.3 +/- 2.5 and 24.3 +/- 3.2 kJ/mol, respectively, compared to 37.2 +/- 6.5 kJ/mol in horseradish peroxidase (HRP), which may be a result of the more facile electron transfer of an internally bound substrate in DHPA. The x-ray crystal structure of DHPA bound with DCP determined at 1.48 A resolution, shows tight substrate binding inside the heme pocket of DHPA (PDB 8EJN). This research contributes to the studies of DHP as a naturally occurring bioremediation enzyme capable of oxidizing a wide range of environmental pollutants. CI - Copyright (c) 2023 Elsevier Inc. All rights reserved. FAU - Aktar, Mst Sharmin AU - Aktar MS AD - Department of Chemistry, North Carolina State University, Raleigh, NC 27695, United States of America. FAU - de Serrano, Vesna AU - de Serrano V AD - Department of Chemistry, North Carolina State University, Raleigh, NC 27695, United States of America. FAU - Ghiladi, Reza AU - Ghiladi R AD - Department of Chemistry, North Carolina State University, Raleigh, NC 27695, United States of America. FAU - Franzen, Stefan AU - Franzen S AD - Department of Chemistry, North Carolina State University, Raleigh, NC 27695, United States of America. Electronic address: franzen@ncsu.edu. LA - eng PT - Comparative Study PT - Journal Article PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20230717 PL - United States TA - J Inorg Biochem JT - Journal of inorganic biochemistry JID - 7905788 RN - R669TG1950 (2,4-dichlorophenol) RN - 0 (Chlorophenols) RN - 0 (Coloring Agents) RN - 42VZT0U6YR (Heme) RN - EC 1.11.1.7 (Peroxidase) RN - EC 1.11.1.- (Peroxidases) RN - 0 (Phenols) SB - IM MH - *Chlorophenols MH - Coloring Agents MH - Heme MH - Peroxidase MH - Peroxidases MH - *Phenols OTO - NOTNLM OT - 2,4-dichlorophenol OT - Activation energy OT - Enzyme kinetics OT - Peroxidase OT - Solvent effect OT - electron transfer COIS- Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. EDAT- 2023/07/23 01:11 MHDA- 2023/08/21 06:42 CRDT- 2023/07/22 18:07 PHST- 2023/05/30 00:00 [received] PHST- 2023/07/11 00:00 [revised] PHST- 2023/07/14 00:00 [accepted] PHST- 2023/08/21 06:42 [medline] PHST- 2023/07/23 01:11 [pubmed] PHST- 2023/07/22 18:07 [entrez] AID - S0162-0134(23)00214-3 [pii] AID - 10.1016/j.jinorgbio.2023.112332 [doi] PST - ppublish SO - J Inorg Biochem. 2023 Oct;247:112332. doi: 10.1016/j.jinorgbio.2023.112332. Epub 2023 Jul 17.