@article{popescu_dinh_chen_miller_washburn_mcguire_dumarieh_d'antonio_ghiladi_2022, title={Mossbauer studies of the ferryl, ferrous and ferric states of dehaloperoxidase from A. ornata}, volume={234}, ISSN={["1873-3344"]}, DOI={10.1016/j.jinorgbio.2022.111867}, abstractNote={Dehaloperoxidase (DHP) is a multi-functional catalytic globin from the marine worm A. ornata, whose physiological functions include oxygen transport and oxidation of toxic substrates present in its habitat. In the Fe(III) state, DHPA has an isomer shift of 0.42 mm/s, characteristic for high-spin heme proteins. Changes in pH have subtle effects on the electronic structure of DHP in the Fe(III) state detectable in the high-field spectra, which show a pH-dependent mixture of species with different zero-field splittings between 5 and 18 cm-1. The short-lived intermediate obtained by direct reaction of the Fe(III) enzyme with H2O2 has an isomer shift of 0.10 mm/s, indicative of an Fe(IV)-oxo state and of an S = 1 electronic ground state confirmed by variable field studies. The O2-bound state of DHP has an isomer shift of 0.28 mm/s and a high-field spectrum characteristic for diamagnetic heme complexes, similarly to other haemoglobins. Overall, the isomer shift and quadrupole splitting of DHP in the four states studied are expectedly similar to both peroxidases and to myoglobin. The differences in electronic structure between DHP and other heme proteins and enzyme are observed in the high-field Mössbauer spectra of the ferric state, which show pH-dependent zero-field splittings suggesting a heme site in which the ligand field strength at the iron ion is tuned by pH. This tunability is correlated with variable electron-donating properties of the iron, which can perform multiple functions.}, journal={JOURNAL OF INORGANIC BIOCHEMISTRY}, author={Popescu, C. V. and Dinh, Thanhminh and Chen, Hongli and Miller, Danielle and Washburn, Anastasia and McGuire, Ashlyn and Dumarieh, Rania and D'Antonio, Jennifer and Ghiladi, Reza A.}, year={2022}, month={Sep} }
 @article{thompson_shay_serrano_dumarieh_ghiladi_franzen_2021, title={A new inhibition mechanism in the multifunctional catalytic hemoglobin dehaloperoxidase as revealed by the DHP A(V59W) mutant: A spectroscopic and crystallographic study}, volume={25}, ISSN={["1099-1409"]}, DOI={10.1142/S1088424621500826}, abstractNote={ As multifunctional catalytic hemoglobins, dehaloperoxidase isoenzymes A and B (DHP A and B) are among the most versatile hemoproteins in terms of activities displayed. The ability of DHP to bind over twenty different substrates in the distal pocket might appear to resemble the promiscuousness of monooxygenase enzymes, yet there are identifiable substrate-specific interactions that can steer the type of oxidation (O-atom vs. electron transfer) that occurs inside the DHP distal pocket. Here, we have investigated the DHP A(V59W) mutant in order to probe the limits of conformational flexibility in the distal pocket as it relates to the genesis of this substrate-dependent activity differentiation. The X-ray crystal structure of the metaquo DHP A(V59W) mutant (PDB 3K3U) and the V59W mutant in complex with fluoride [denoted as DHP A(V59W-F)] (PDB 7MNH) show significant mobility of the tryptophan in the distal pocket, with two parallel conformations having W59-N[Formula: see text] H-bonded to a heme-bound ligand (H2O or F[Formula: see text], and another conformation [observed only in DHP A(V59W-F)] that brings W59 sufficiently close to the heme as to preclude axial ligand binding. UV-vis and resonance Raman spectroscopic studies show that DHP A(V59W) is 5-coordinate high spin (5cHS) at pH 5 and 6-coordinate high spin (6cHS) at pH 7, whereas DHP A(V59W-F) is 6cHS from pH 5 to 7. Enzyme assays confirm robust peroxidase activity at pH 5, but complete loss of activity at pH 7. We find no evidence that tryptophan plays a role in the oxidation mechanism ([Formula: see text]. radical formation). Instead, the data reveal a new mechanism of DHP inhibition, namely a shift towards a non-reactive form by OH[Formula: see text] ligation to the heme-Fe that is strongly stabilized (presumably through H-bonding interactions) by the presence of W59 in the distal cavity. }, number={7-8}, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, author={Thompson, Matthew K. and Shay, Madeline R. and Serrano, Vesna and Dumarieh, Rania and Ghiladi, Reza A. and Franzen, Stefan}, year={2021}, month={Jul}, pages={756–771} }
 @article{dumarieh_d'antonio_deliz-liang_smirnova_svistunenko_ghiladi_2013, title={Tyrosyl radicals in dehaloperoxidase how nature deals with evolving an oxygen-binding globin to a biologically relevant peroxidase}, volume={288}, number={46}, journal={Journal of Biological Chemistry}, author={Dumarieh, R. and D'Antonio, J. and Deliz-Liang, A. and Smirnova, T. and Svistunenko, D. A. and Ghiladi, R. A.}, year={2013}, pages={33470–33482} }
 @article{franzen_sasan_sturgeon_lyon_battenburg_gracz_dumariah_ghiladi_2012, title={Nonphotochemical Base-Catalyzed Hydroxylation of 2,6-Dichloroquinone by H2O2Occurs by a Radical Mechanism}, volume={116}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp208536x}, DOI={10.1021/jp208536x}, abstractNote={Kinetic and structural studies have shown that peroxidases are capable of the oxidation of 2,4,6-trichlorophenol (2,4,6-TCP) to 2,6-dichloro-1,4-benzoquinone (2,6-DCQ). Further reactions of 2,6-DCQ in the presence of H(2)O(2) and OH(-) yield 2,6-dichloro-3-hydroxy-1,4-benzoquinone (2,6-DCQOH). The reactions of 2,6-DCQ have been monitored spectroscopically [UV-visible and electron spin resonance (ESR)] and chromatographically. The hydroxylation product, 2,6-DCQOH, has been observed by UV-visible and characterized structurally by (1)H and (13)C NMR spectroscopy. The results are consistent with a nonphotochemical base-catalyzed oxidation of 2,6-DCQ at pH > 7. Because H(2)O(2) is present in peroxidase reaction mixtures, there is also a potential role for the hydrogen peroxide anion (HOO(-)). However, in agreement with previous work, we observe that the nonphotochemical epoxidation by H(2)O(2) at pH < 7 is immeasurably slow. Both room-temperature ESR and rapid-freeze-quench ESR methods were used to establish that the dominant nonphotochemical mechanism involves formation of a semiquinone radical (base -catalyzed pathway), rather than epoxidation (direct attack by H(2)O(2) at low pH). Analysis of the kinetics using an Arrhenius model permits determination of the activation energy of hydroxylation (E(a) = 36 kJ/mol), which is significantly lower than the activation energy of the peroxidase-catalyzed oxidation of 2,4,6-TCP (E(a) = 56 kJ/mol). However, the reaction is second order in both 2,6-DCQ and OH(-) so that its rate becomes significant above 25 °C due to the increased rate of formation of 2,6-DCQ that feeds the second-order process. The peroxidase used in this study is the dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata , which is used to study the effect of a catalyst on the reactions. The control experiments and precedents in studies of other peroxidases lead to the conclusion that hydroxylation will be observed following any process that leads to the formation of the 2,6-DCQ at pH > 7, regardless of the catalyst used in the 2,4,6-TCP oxidation reaction.}, number={5}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Franzen, Stefan and Sasan, Koroush and Sturgeon, Bradley E. and Lyon, Blake J. and Battenburg, Benjamin J. and Gracz, Hanna and Dumariah, Rania and Ghiladi, Reza}, year={2012}, month={Jan}, pages={1666–1676} }
 @article{zhao_de serrano_dumarieh_thompson_ghiladi_franzen_2012, title={The Role of the Distal Histidine in H2O2 Activation and Heme Protection in both Peroxidase and Globin Functions}, volume={116}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp300014b}, DOI={10.1021/jp300014b}, abstractNote={The distal histidine mutations of dehaloperoxidase-hemoglobin A (DHP A) to aspartate (H55D) and asparagine (H55N) have been prepared to study the role played by the distal histidine in both activation and protection against oxidation by radicals in heme proteins. The H55D and H55N mutants of DHP A have ~6-fold and ~11-fold lower peroxidase activities than wild type enzyme toward the oxidation of 2,4,6-trichlorophenol (TCP) to yield 2,6-dichloroquinone (DCQ) in the presence of H(2)O(2). The origin of the lower rate constants may be the solvent-exposed conformations of distal D55 and N55, which would have the dual effect of destabilizing the binding of H(2)O(2) to the heme iron, and of removing the acid-base catalyst necessary for the heterolytic O-O bond cleavage of heme-bound H(2)O(2) (i.e., compound 0). The partial peroxidase activity of H55D can be explained if one considers that there are two conformations of the distal aspartate (open and closed) by analogy with the distal histidine. We hypothesize that the distal aspartate has an active conformation in the distal pocket (closed). Although the open form is observed in the low-temperature X-ray crystal structure of ferric H55D, the closed form is observed in the FTIR spectrum of the carbonmonoxy form of the H55D mutant. Consistent with this model, the H55D mutant also shows inhibition of TCP oxidation by 4-bromophenol (4-BP). Consistent with the protection hypothesis, compound ES, the tyrosyl radical-containing ferryl intermediate observed in WT DHP A, was not observed in H55D.}, number={40}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Zhao, Junjie and de Serrano, Vesna and Dumarieh, Rania and Thompson, Matt and Ghiladi, Reza A. and Franzen, Stefan}, year={2012}, month={Sep}, pages={12065–12077} }
 @article{feducia_dumarieh_gilvey_smirnova_franzen_ghiladi_2009, title={Characterization of Dehaloperoxidase Compound ES and Its Reactivity with Trihalophenols†}, volume={48}, ISSN={0006-2960 1520-4995}, url={http://dx.doi.org/10.1021/bi801916j}, DOI={10.1021/bi801916j}, abstractNote={Dehaloperoxidase (DHP), the oxygen transport hemoglobin from the terebellid polychaete Amphitrite ornata, is the first globin identified to possess a biologically relevant peroxidase activity. DHP has been shown to oxidize trihalophenols to dihaloquinones in a dehalogenation reaction that uses hydrogen peroxide as a substrate. Herein, we demonstrate that the first detectable intermediate following the addition of hydrogen peroxide to ferric DHP contains both a ferryl heme and a tyrosyl radical, analogous to Compound ES of cytochrome c peroxidase. Furthermore, we provide a detailed kinetic description for the reaction of preformed DHP Compound ES with the substrate 2,4,6-trichlorophenol and demonstrate the catalytic competency of this intermediate in generating the product 2,4-dichloroquinone. Using rapid-freeze-quench electron paramagnetic resonance spectroscopy, we detected a g approximately 2.0058 signal confirming the presence of a protein radical in DHP Compound ES. In the absence of substrate, DHP Compound ES evolves to a new species, Compound RH, which is functionally unique to dehaloperoxidase. We propose that this intermediate plays a protective role against heme bleaching. While unreactive toward further oxidation, Compound RH can be reduced and subsequently bind dioxygen, generating oxyferrous DHP, which may represent the catalytic link between peroxidase and oxygen transport activities in this bifunctional protein.}, number={5}, journal={Biochemistry}, publisher={American Chemical Society (ACS)}, author={Feducia, Jeremiah and Dumarieh, Rania and Gilvey, Lauren B. G. and Smirnova, Tatyana and Franzen, Stefan and Ghiladi, Reza A.}, year={2009}, month={Feb}, pages={995–1005} }