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Conformationally distinct five-coordinate heme-NO complexes of soluble guanylate cyclase elucidated by multifrequency electron paramagnetic resonance (EPR).

Publication ,  Journal Article
Gunn, A; Derbyshire, ER; Marletta, MA; Britt, RD
Published in: Biochemistry
October 2012

Soluble guanylate cyclase (sGC) is a heme-containing enzyme that senses nitric oxide (NO). Formation of a heme Fe-NO complex is essential to sGC activation, and several spectroscopic techniques, including electron paramagnetic resonance (EPR) spectroscopy, have been aimed at elucidating the active enzyme conformation. Of these, only EPR spectra (X-band ~9.6 GHz) have shown differences between low- and high-activity Fe-NO states, and these states are modeled in two different heme domain truncations of sGC, β1(1-194) and β2(1-217), respectively (Derbyshire et al., Biochemistry 2008, 47, 3892-3899). The EPR signal of the low-activity sGC Fe-NO complex exhibits a broad lineshape that has been interpreted as resulting from site-to-site inhomogeneity, and simulated using g strain, a continuous distribution about the principal values of a given g tensor. This approach, however, fails to account for visible features in the X-band EPR spectra as well as the g anisotropy observed at higher microwave frequencies. Herein we analyze X-, Q-, and D-band EPR spectra and show that both the broad lineshape and the spectral structure of the sGC EPR signal at multiple microwave frequencies can be simulated successfully with a superposition of only two distinct g tensors. These tensors represent different populations that likely differ in Fe-NO bond angle, hydrogen bonding, or the geometry of the amino acid residues. One of these conformations can be linked to a form of the enzyme with higher activity.

Duke Scholars

Published In

Biochemistry

DOI

EISSN

1520-4995

ISSN

0006-2960

Publication Date

October 2012

Volume

51

Issue

42

Start / End Page

8384 / 8390

Related Subject Headings

  • Soluble Guanylyl Cyclase
  • Receptors, Cytoplasmic and Nuclear
  • Rats
  • Protein Structure, Tertiary
  • Nitric Oxide
  • Heme
  • Guanylate Cyclase
  • Electron Spin Resonance Spectroscopy
  • Biochemistry & Molecular Biology
  • Animals
 

Citation

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Gunn, A., Derbyshire, E. R., Marletta, M. A., & Britt, R. D. (2012). Conformationally distinct five-coordinate heme-NO complexes of soluble guanylate cyclase elucidated by multifrequency electron paramagnetic resonance (EPR). Biochemistry, 51(42), 8384–8390. https://doi.org/10.1021/bi300831m
Gunn, Alexander, Emily R. Derbyshire, Michael A. Marletta, and R David Britt. “Conformationally distinct five-coordinate heme-NO complexes of soluble guanylate cyclase elucidated by multifrequency electron paramagnetic resonance (EPR).Biochemistry 51, no. 42 (October 2012): 8384–90. https://doi.org/10.1021/bi300831m.
Gunn, Alexander, et al. “Conformationally distinct five-coordinate heme-NO complexes of soluble guanylate cyclase elucidated by multifrequency electron paramagnetic resonance (EPR).Biochemistry, vol. 51, no. 42, Oct. 2012, pp. 8384–90. Epmc, doi:10.1021/bi300831m.
Journal cover image

Published In

Biochemistry

DOI

EISSN

1520-4995

ISSN

0006-2960

Publication Date

October 2012

Volume

51

Issue

42

Start / End Page

8384 / 8390

Related Subject Headings

  • Soluble Guanylyl Cyclase
  • Receptors, Cytoplasmic and Nuclear
  • Rats
  • Protein Structure, Tertiary
  • Nitric Oxide
  • Heme
  • Guanylate Cyclase
  • Electron Spin Resonance Spectroscopy
  • Biochemistry & Molecular Biology
  • Animals