Effect of temperature, pH and heme ligands on the reduction of Cygb(Fe 3+) by ascorbate

Jianjing Tong, Joseph R. Zweier, Rachael L. Huskey, Raed S. Ismail, Craig Hemann, Jay L. Zweier, Xiaoping Liu

Research output: Contribution to journalArticlepeer-review


Cytoglobin (Cygb) plays a role in regulating vasodilation in response to changes in local oxygen concentration by altering the rate of nitric oxide (NO) metabolism. Because the reduction of Cygb(Fe3+) by a reductant is the control step for Cygb-mediated NO metabolism, we examined the effects of temperature, pH, and heme ligands on the Cygb(Fe3+) reduction by ascorbate (Asc) under anaerobic conditions. The standard enthalpy of Cygb(Fe3+) reduction by Asc was determined to be 42.4 ± 3.1 kJ/mol. The rate of Cygb(Fe3+) reduction increased ∼6% per °C when temperature varied from 35°C to 40°C. The yield and the rate of Cygb(Fe3+) reduction significantly increases with pH (2-3 times per pH unit), paralleling the formation of the Asc ion (A2-) and the increased stability of reduced state of heme iron at high pH values. Heme ligand cyanide (CN-) decreased the yield and the rate of Cygb(Fe 3+) reduction, but ligands CO and NO allowed the process of Cygb(Fe3+) reduction to continue to completion. Critical information is provided for modeling and prediction of the process of Cygb-mediated NO metabolism in vessels in a range of temperature and pH values.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalArchives of Biochemistry and Biophysics
StatePublished - Jul 15 2014
Externally publishedYes


  • Ascorbate
  • Cytoglobin
  • Heme ligand
  • pH
  • Temperature

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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