Suppression of Methemoglobin Formation by Glutathione in a Concentrated Hemoglobin Solution and in a Hemoglobin-Vesicle

• Published in: Bulletin of the Chemical Society of Japan Vol. 67; no. 4; pp. 1120 - 1125
• Main Authors: Sakai, Hiromi, Takeoka, Shinji, Seino, Yuriko, Tsuchida, Eishun
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 01.04.1994; Chemical Society of Japan
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Hemoproteins; Metalloproteins; Proteins; Hemoglobin; Hemoprotein; Inhibition; Reaction; Blood substitute; Glutathione
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.67.1120

The suppression of methemoglobin (metHb) formation by glutathione (GSH) is difficult because GSH is oxidized not only by the reduction of metHb, but also by oxygen to generate active oxygen species, such as superoxide (O2−•) and hydrogen peroxide (H2O2), which contribute to metHb formation. An effective nonenzymatic reduction of metHb was achieved at a high concentration of Hb (40 wt%, 2.48 × 10−2 M subunits (1 M = 1 mol dm−3)) because the reduction of metHb was accelerated, and at a low partial pressure of oxygen (pO2 = 40 Torr (1 Torr = 133.322 Pa)) because the oxidation of GSH was effectively suppressed. Hb-vesicles, which encapsulate concentrated Hb (40 wt%, 2.48 × 10−2 M subunits), transport oxygen in the blood stream at relatively low pO2 (110 Torr in artery and 40 Torr in venous, 58 Torr in average). The rate of metHb formation in Hb-vesicles was effectively decreased from 3.8 × 10−7 to 1.6 × 10−7 M s−1 by coencapsulating GSH at 58 Torr.