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An investigation of hemopexin redox properties by spectroelectrochemistry: biological relevance for heme uptake.

Publication ,  Journal Article
Flaherty, MM; Rish, KR; Smith, A; Crumbliss, AL
Published in: Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine
June 2008

Hemopexin (HPX) has two principal roles: it sequesters free heme in vivo for the purpose of preventing the toxic effects of this moiety, which is largely due to heme's ability to catalyze free radical formation, and it transports heme intracellularly thus limiting its availability as an iron source for pathogens. Spectroelectrochemistry was used to determine the redox potential for heme and meso-heme (mH) when bound by HPX. At pH 7.2, the heme-HPX assembly exhibits E (1/2) values in the range 45-90 mV and the mH-HPX assembly in the range 5-55 mV, depending on environmental electrolyte identity. The E (1/2) value exhibits a 100 mV positive shift with a change in pH from 7.2 to 5.5 for mH-HPX, suggesting a single proton dependent equilibrium. The E (1/2) values for heme-HPX are more positive in the presence of NaCl than KCl indicating that Na(+), as well as low pH (5.5) stabilizes ferro-heme-HPX. Furthermore, comparing KCl with K(2)HPO(4), the chloride salt containing system has a lower potential, indicating that heme-HPX is easier to oxidize. These physical properties related to ferri-/ferro-heme reduction are both structurally and biologically relevant for heme release from HPX for transport and regulation of heme oxygenase expression. Consistent with this, when the acidification of endosomes is prevented by bafilomycin then heme oxygenase-1 induction by heme-HPX no longer occurs.

Duke Scholars

Published In

Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine

DOI

EISSN

1572-8773

ISSN

0966-0844

Publication Date

June 2008

Volume

21

Issue

3

Start / End Page

239 / 248

Related Subject Headings

  • Spectrophotometry
  • Protein Structure, Tertiary
  • Oxidation-Reduction
  • Models, Molecular
  • Mice
  • Hemopexin
  • Heme Oxygenase-1
  • Heme
  • Electrolytes
  • Electrochemistry
 

Citation

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MLA
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Flaherty, M. M., Rish, K. R., Smith, A., & Crumbliss, A. L. (2008). An investigation of hemopexin redox properties by spectroelectrochemistry: biological relevance for heme uptake. Biometals : An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine, 21(3), 239–248. https://doi.org/10.1007/s10534-007-9112-9
Flaherty, Meghan M., Kimberley R. Rish, Ann Smith, and Alvin L. Crumbliss. “An investigation of hemopexin redox properties by spectroelectrochemistry: biological relevance for heme uptake.Biometals : An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine 21, no. 3 (June 2008): 239–48. https://doi.org/10.1007/s10534-007-9112-9.
Flaherty MM, Rish KR, Smith A, Crumbliss AL. An investigation of hemopexin redox properties by spectroelectrochemistry: biological relevance for heme uptake. Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine. 2008 Jun;21(3):239–48.
Flaherty, Meghan M., et al. “An investigation of hemopexin redox properties by spectroelectrochemistry: biological relevance for heme uptake.Biometals : An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine, vol. 21, no. 3, June 2008, pp. 239–48. Epmc, doi:10.1007/s10534-007-9112-9.
Flaherty MM, Rish KR, Smith A, Crumbliss AL. An investigation of hemopexin redox properties by spectroelectrochemistry: biological relevance for heme uptake. Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine. 2008 Jun;21(3):239–248.
Journal cover image

Published In

Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine

DOI

EISSN

1572-8773

ISSN

0966-0844

Publication Date

June 2008

Volume

21

Issue

3

Start / End Page

239 / 248

Related Subject Headings

  • Spectrophotometry
  • Protein Structure, Tertiary
  • Oxidation-Reduction
  • Models, Molecular
  • Mice
  • Hemopexin
  • Heme Oxygenase-1
  • Heme
  • Electrolytes
  • Electrochemistry