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Redox properties of human hemoglobin in complex with fractionated dimeric and polymeric human haptoglobin.

Publication ,  Journal Article
Mollan, TL; Jia, Y; Banerjee, S; Wu, G; Kreulen, RT; Tsai, A-L; Olson, JS; Crumbliss, AL; Alayash, AI
Published in: Free radical biology & medicine
April 2014

Haptoglobin (Hp) is an abundant and conserved plasma glycoprotein, which binds acellular adult hemoglobin (Hb) dimers with high affinity and facilitates their rapid clearance from circulation after hemolysis. Humans possess three main phenotypes of Hp, designated Hp 1-1, Hp 2-1, and Hp 2-2. These variants exhibit diverse structural configurations and have been reported to be functionally nonequivalent. We have investigated the functional and redox properties of Hb-Hp complexes prepared using commercially fractionated Hp and found that all forms exhibit similar behavior. The rate of Hb dimer binding to Hp occurs with bimolecular rate constants of ~0.9 μM(-1) s(-1), irrespective of the type of Hp assayed. Although Hp binding does accelerate the observed rate of HbO2 autoxidation by dissociating Hb tetramers into dimers, the rate observed for these bound dimers is three- to fourfold slower than that of Hb dimers free in solution. Co-incubation of ferric Hb with any form of Hp inhibits heme loss to below detectable levels. Intrinsic redox potentials (E1/2) of the ferric/ferrous pair of each Hb-Hp complex are similar, varying from +54 to +59 mV (vs NHE), and are essentially the same as reported by us previously for Hb-Hp complexes prepared from unfractionated Hp. All Hb-Hp complexes generate similar high amounts of ferryl Hb after exposure to hydrogen peroxide. Electron paramagnetic resonance data indicate that the yields of protein-based radicals during this process are approximately 4 to 5% and are unaffected by the variant of Hp assayed. These data indicate that the Hp fractions examined are equivalent to one another with respect to Hb binding and associated stability and redox properties and that this result should be taken into account in the design of phenotype-specific Hp therapeutics aimed at countering Hb-mediated vascular disease.

Duke Scholars

Published In

Free radical biology & medicine

DOI

EISSN

1873-4596

ISSN

0891-5849

Publication Date

April 2014

Volume

69

Start / End Page

265 / 277

Related Subject Headings

  • Polymers
  • Phenotype
  • Oxidation-Reduction
  • Multiprotein Complexes
  • Kinetics
  • Hydrogen Peroxide
  • Humans
  • Hemoglobins
  • Haptoglobins
  • Electron Spin Resonance Spectroscopy
 

Citation

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Mollan, T. L., Jia, Y., Banerjee, S., Wu, G., Kreulen, R. T., Tsai, A.-L., … Alayash, A. I. (2014). Redox properties of human hemoglobin in complex with fractionated dimeric and polymeric human haptoglobin. Free Radical Biology & Medicine, 69, 265–277. https://doi.org/10.1016/j.freeradbiomed.2014.01.030
Mollan, Todd L., Yiping Jia, Sambuddha Banerjee, Gang Wu, R Timothy Kreulen, Ah-Lim Tsai, John S. Olson, Alvin L. Crumbliss, and Abdu I. Alayash. “Redox properties of human hemoglobin in complex with fractionated dimeric and polymeric human haptoglobin.Free Radical Biology & Medicine 69 (April 2014): 265–77. https://doi.org/10.1016/j.freeradbiomed.2014.01.030.
Mollan TL, Jia Y, Banerjee S, Wu G, Kreulen RT, Tsai A-L, et al. Redox properties of human hemoglobin in complex with fractionated dimeric and polymeric human haptoglobin. Free radical biology & medicine. 2014 Apr;69:265–77.
Mollan, Todd L., et al. “Redox properties of human hemoglobin in complex with fractionated dimeric and polymeric human haptoglobin.Free Radical Biology & Medicine, vol. 69, Apr. 2014, pp. 265–77. Epmc, doi:10.1016/j.freeradbiomed.2014.01.030.
Mollan TL, Jia Y, Banerjee S, Wu G, Kreulen RT, Tsai A-L, Olson JS, Crumbliss AL, Alayash AI. Redox properties of human hemoglobin in complex with fractionated dimeric and polymeric human haptoglobin. Free radical biology & medicine. 2014 Apr;69:265–277.
Journal cover image

Published In

Free radical biology & medicine

DOI

EISSN

1873-4596

ISSN

0891-5849

Publication Date

April 2014

Volume

69

Start / End Page

265 / 277

Related Subject Headings

  • Polymers
  • Phenotype
  • Oxidation-Reduction
  • Multiprotein Complexes
  • Kinetics
  • Hydrogen Peroxide
  • Humans
  • Hemoglobins
  • Haptoglobins
  • Electron Spin Resonance Spectroscopy