Abstract
Oxidation of oxyhemoglobin by nitrite is characterized by the presence of a lag phase followed by the autocatalysis. In phosphate buffer, an asymmetric ESR signal is detected at g = 2.005 (hereafter referred to as the g = 2 radical) during the oxidation which is similar to that of the methemoglobin free radical generated from methemoglobin and H2O2. Catalase and KCN prolong the oxidation, indicating the involvement of H2O2 and methemoglobin in the reaction. Superoxide dismutase, on the other hand, does not modify the oxidation. The present results suggest a chain reaction mechanism for the oxidation in which the g = 2 radical catalyzes the formation of NO2 from NO2 - by a peroxidase action and NO2 oxidizes oxyhemoglobin. However, in N,N-bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (bistris) buffer, superoxide dismutase markedly elongates the lag phase and accelerates the autocatalysis: bistris scavenges the g = 2 radical and a radical derived from bistris reduces O2 to O2 -.
| Original language | English |
|---|---|
| Journal | Biomedica Biochimica Acta |
| Volume | 42 |
| Issue number | 11-12 |
| Publication status | Published - 1983 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Biochemistry
Cite this
Mechanism of autocatalytic oxidation of oxyhemoglobin by nitrite. / Kosaka, H.; Tyuma, I.; Imaizumi, K.
In: Biomedica Biochimica Acta, Vol. 42, No. 11-12, 1983.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mechanism of autocatalytic oxidation of oxyhemoglobin by nitrite
AU - Kosaka, H.
AU - Tyuma, I.
AU - Imaizumi, K.
PY - 1983
Y1 - 1983
N2 - Oxidation of oxyhemoglobin by nitrite is characterized by the presence of a lag phase followed by the autocatalysis. In phosphate buffer, an asymmetric ESR signal is detected at g = 2.005 (hereafter referred to as the g = 2 radical) during the oxidation which is similar to that of the methemoglobin free radical generated from methemoglobin and H2O2. Catalase and KCN prolong the oxidation, indicating the involvement of H2O2 and methemoglobin in the reaction. Superoxide dismutase, on the other hand, does not modify the oxidation. The present results suggest a chain reaction mechanism for the oxidation in which the g = 2 radical catalyzes the formation of NO2 from NO2 - by a peroxidase action and NO2 oxidizes oxyhemoglobin. However, in N,N-bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (bistris) buffer, superoxide dismutase markedly elongates the lag phase and accelerates the autocatalysis: bistris scavenges the g = 2 radical and a radical derived from bistris reduces O2 to O2 -.
AB - Oxidation of oxyhemoglobin by nitrite is characterized by the presence of a lag phase followed by the autocatalysis. In phosphate buffer, an asymmetric ESR signal is detected at g = 2.005 (hereafter referred to as the g = 2 radical) during the oxidation which is similar to that of the methemoglobin free radical generated from methemoglobin and H2O2. Catalase and KCN prolong the oxidation, indicating the involvement of H2O2 and methemoglobin in the reaction. Superoxide dismutase, on the other hand, does not modify the oxidation. The present results suggest a chain reaction mechanism for the oxidation in which the g = 2 radical catalyzes the formation of NO2 from NO2 - by a peroxidase action and NO2 oxidizes oxyhemoglobin. However, in N,N-bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (bistris) buffer, superoxide dismutase markedly elongates the lag phase and accelerates the autocatalysis: bistris scavenges the g = 2 radical and a radical derived from bistris reduces O2 to O2 -.
UR - http://www.scopus.com/inward/record.url?scp=0020918417&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0020918417&partnerID=8YFLogxK
M3 - Article
C2 - 6326765
AN - SCOPUS:0020918417
VL - 42
JO - Biomedica Biochimica Acta
JF - Biomedica Biochimica Acta
SN - 0232-766X
IS - 11-12
ER -