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Title: Nonmicrobial Nitrophenol Degradation via Peroxygenase Activity of Dehaloperoxidase-Hemoglobin from Amphitrite ornata

Authors:
; ; ; ;  [1]
  1. NCSU
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NSFU.S. ARMY RESEARCHUNIVERSITYNIH
OSTI Identifier:
1251221
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemistry; Journal Volume: 55; Journal Issue: (17) ; 04, 2016
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

McCombs, Nikolette L., D’Antonio, Jennifer, Barrios, David A., Carey, Leiah M., and Ghiladi, Reza A. Nonmicrobial Nitrophenol Degradation via Peroxygenase Activity of Dehaloperoxidase-Hemoglobin from Amphitrite ornata. United States: N. p., 2016. Web. doi:10.1021/acs.biochem.6b00143.
McCombs, Nikolette L., D’Antonio, Jennifer, Barrios, David A., Carey, Leiah M., & Ghiladi, Reza A. Nonmicrobial Nitrophenol Degradation via Peroxygenase Activity of Dehaloperoxidase-Hemoglobin from Amphitrite ornata. United States. doi:10.1021/acs.biochem.6b00143.
McCombs, Nikolette L., D’Antonio, Jennifer, Barrios, David A., Carey, Leiah M., and Ghiladi, Reza A. Wed . "Nonmicrobial Nitrophenol Degradation via Peroxygenase Activity of Dehaloperoxidase-Hemoglobin from Amphitrite ornata". United States. doi:10.1021/acs.biochem.6b00143.
@article{osti_1251221,
title = {Nonmicrobial Nitrophenol Degradation via Peroxygenase Activity of Dehaloperoxidase-Hemoglobin from Amphitrite ornata},
author = {McCombs, Nikolette L. and D’Antonio, Jennifer and Barrios, David A. and Carey, Leiah M. and Ghiladi, Reza A.},
abstractNote = {},
doi = {10.1021/acs.biochem.6b00143},
journal = {Biochemistry},
number = (17) ; 04, 2016,
volume = 55,
place = {United States},
year = {Wed May 04 00:00:00 EDT 2016},
month = {Wed May 04 00:00:00 EDT 2016}
}
  • The crystal structures of the dehaloperoxidase-hemoglobin from A. ornata (DHP A) each report a crystallographic dimer in the unit cell. Yet, the largest dimer interface observed is 450 {angstrom}{sup 2}, an area significantly smaller than the typical value of 1200-2000 {angstrom}{sup 2} and in contrast to the extensive interface region of other known dimeric hemoglobins. To examine the oligomerization state of DHP A in solution, we used gel permeation by fast protein liquid chromatography and small-angle X-ray scattering (SAXS). Gel permeation experiments demonstrate that DHP A elutes as a monomer (15.5 kDa) and can be separated from green fluorescent protein,more » which has a molar mass of 27 kDa, near the 31 kDa expected for the DHP A dimer. By SAXS, we found that DHP A is primarily monomeric in solution, but with a detectable level of dimer (10%), under all conditions studied up to a protein concentration of 3.0 mM. These concentrations are likely 10-100-fold lower than the K{sub d} for dimer formation. Additionally, there was no significant effect either on the overall conformation of DHP A or its monomer-dimer equilibrium upon addition of the DHP A inhibitor, 4-iodophenol.« less
  • Sea worm, Amphitrite ornata, has evolved its globin (an O 2 carrier) also to serves as a dehaloperoxidase (DHP) to detoxify haloaromatic pollutants generated by competing species. A previous mutagenesis study by our groups on both DHP and sperm whale myoglobin (SW Mb) revealed some structural factors that influence the dehaloperoxidase activities (significantly lower for Mb) of both proteins. Using an isocyanide/O 2 partition constant measurement method in this study, we have examined the effects of these structural factors on the O 2 equilibrium constants (K O2) of DHP, SW Mb, and their mutants. A clear trend of decreasing Omore » 2 affinity and increasing catalytic activity along with the increase in the distal His N ε–heme iron distance is observed. An H93K/T95H Mb double mutant mimicking the DHP proximal His positioning exhibited markedly enhanced O 2 affinity, confirming the essential effect of proximal His rotation on the globin function of DHP. For DHP, the L100F, T56G and M86E variants showed the effects of distal volume, distal His flexibility and proximal electronic push, respectively, on the O 2 affinity. This study provides insights into how DHP has evolved its heme environment to gain significantly enhanced peroxidase capability without compromising its primary function as an O 2 carrier.« less
  • X-ray crystal structures of the metcyano form of dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata (DHPCN) and the C73S mutant of DHP A (C73SCN) were determined using synchrotron radiation in order to further investigate the geometry of diatomic ligands coordinated to the heme iron. The DHPCN structure was also determined using a rotating-anode source. The structures show evidence of photoreduction of the iron accompanied by dissociation of bound cyanide ion (CN{sup -}) that depend on the intensity of the X-ray radiation and the exposure time. The electron density is consistent with diatomic molecules located in two sites in the distal pocketmore » of DHPCN. However, the identities of the diatomic ligands at these two sites are not uniquely determined by the electron-density map. Consequently, density functional theory calculations were conducted in order to determine whether the bond lengths, angles and dissociation energies are consistent with bound CN{sup -} or O{sub 2} in the iron-bound site. In addition, molecular-dynamics simulations were carried out in order to determine whether the dynamics are consistent with trapped CN{sup -} or O{sub 2} in the second site of the distal pocket. Based on these calculations and comparison with a previously determined X-ray crystal structure of the C73S-O{sub 2} form of DHP [de Serrano et al. (2007), Acta Cryst. D63, 1094-1101], it is concluded that CN{sup -} is gradually replaced by O{sub 2} as crystalline DHP is photoreduced at 100 K. The ease of photoreduction of DHP A is consistent with the reduction potential, but suggests an alternative activation mechanism for DHP A compared with other peroxidases, which typically have reduction potentials that are 0.5 V more negative. The lability of CN{sup -} at 100 K suggests that the distal pocket of DHP A has greater flexibility than most other hemoglobins.« less