Effect of temperature, pH and heme ligands on the reduction of Cygb(Fe(3+)) by ascorbate.
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(Fe(3+)) 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(Fe(3+)) reduction by ascorbate (Asc) under anaerobic conditions. The standard enthalpy of Cygb(Fe(3+)) reduction by Asc was determined to be 42.4 ± 3.1 kJ/mol. The rate of Cygb(Fe(3+)) reduction increased ~6% per °C when temperature varied from 35°C to 40°C. The yield and the rate of Cygb(Fe(3+)) reduction significantly increases with pH (2-3 times per pH unit), paralleling the formation of the Asc ion (A(2-)) 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(Fe(3+)) 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.
Emergency Department, Shanghai Ruijin Hospital, Shanghai Jiaotong University School of Medicine, 197 Ruijin Er Road, Shanghai 200025, China; Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA.
Jianjing
J
Tong
Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA.
Joseph R
JR
Zweier
Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA.
Rachael L
RL
Huskey
Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA.
Raed S
RS
Ismail
Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA.
Craig
C
Hemann
Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH, USA. Electronic address: jay.zweier@osumc.edu.
Jay L
JL
Zweier
Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH, USA. Electronic address: Xiaoping.liu@osumc.edu.
Xiaoping
X
Liu
D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D000078842:Cytoglobin; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism; D005914:Globins / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008024:Ligands; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013696:Temperature
C000627265:CYGB protein, human; D000078842:Cytoglobin; D005290:Ferric Compounds; D008024:Ligands; D009569:Nitric Oxide; D006418:Heme; D005914:Globins; D001205:Ascorbic Acid
Ascorbate; Cytoglobin; Heme ligand; Temperature; pH