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Structure and reactivity of chlorite dismutase nitrosyls.

Authors
  • Geeraerts, Zachary1
  • Heskin, Alisa K1
  • DuBois, Jennifer2
  • Rodgers, Kenton R3
  • Lukat-Rodgers, Gudrun S4
  • 1 North Dakota State University, Fargo, ND 58108, United States of America. , (United States)
  • 2 Montana State University, Bozeman, MT 59717, United States of America. , (United States)
  • 3 North Dakota State University, Fargo, ND 58108, United States of America. Electronic address: [email protected] , (United States)
  • 4 North Dakota State University, Fargo, ND 58108, United States of America. Electronic address: [email protected] , (United States)
Type
Published Article
Journal
Journal of inorganic biochemistry
Publication Date
Oct 01, 2020
Volume
211
Pages
111203–111203
Identifiers
DOI: 10.1016/j.jinorgbio.2020.111203
PMID: 32768737
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Ferric nitrosyl ({FeNO}6) and ferrous nitrosyl ({FeNO}7) complexes of the chlorite dismutases (Cld) from Klebsiella pneumoniae and Dechloromonas aromatica have been characterized using UV-visible absorbance and Soret-excited resonance Raman spectroscopy. Both of these Clds form kinetically stable {FeNO}6 complexes and they occupy a unique region of ν(Fe-NO)/ν(N-O) correlation space for proximal histidine liganded heme proteins, characteristic of weak Fe-NO and N-O bonds. This location is attributed to admixed FeIII-NO character of the {FeNO}6 ground state. Cld {FeNO}6 complexes undergo slow reductive nitrosylation to yield {FeNO}7 complexes. The effects of proximal and distal environment on reductive nitroylsation rates for these dimeric and pentameric Clds are reported. The ν(Fe-NO) and ν(N-O) frequencies for Cld {FeNO}7 complexes reveal both six-coordinate (6c) and five-coordinate (5c) nitrosyl hemes. These 6c and 5c forms are in a pH dependent equilibrium. The 6c and 5c {FeNO}7 Cld frequencies provided positions of both Clds on their respective ν(Fe-NO) vs ν(N-O) correlation lines. The 6c {FeNO}7 complexes fall below (along the ν(Fe-NO) axis) the correlation line that reports hydrogen-bond donation to NNO, which is consistent with a relatively weak Fe-NO bond. Kinetic and spectroscopic evidence is consistent with the 5c {FeNO}7 Clds having NO coordinated on the proximal side of the heme, analogous to 5c {FeNO}7 hemes in proteins known to have NO sensing functions. Copyright © 2020 Elsevier Inc. All rights reserved.

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