منابع مشابه
Properties of methemoglobin reductase and kinetic study of methemoglobin reduction.
A soluble erythrocyte cytochrome b5 was purified as the substrate of methemoglobin reductase and an electron carrier to methemoglobin. The isoelectric point of this protein was at pH 4.3, and E0' was -0.010 at pH 7.0.. The Km value of the enzyme for this protein was 1 x 10(-4) M, and the turnover number (k5) was 3.4 x 10(4) min-1, with NADH as an electron donor at pH 7.0. The optimum pH of the ...
متن کامل[Regulation of methemoglobin reduction in human erythrocytes].
The regulation of methemoglobin reduction in human erythrocytes was studied in vitro in association with glycolytic reactions, by using hemolysates prepared from the nitrate-treated eryth rocytes. The results obtained are as follows; 1) The addition of cytochrome b5 to the reaction mixture containing fructose 1,6-diphosphate as the substrate for glycolysis caused a marked increase in...
متن کاملImpaired erythrocyte methemoglobin reduction in sickle cell disease: dependence of methemoglobin reduction on reduced nicotinamide adenine dinucleotide content.
We have examined aspects of methemoglobin (metHb) reduction in sickle and in thalassemic red blood cells (RBCs). NADH metHb reductase activity in sickle and thalassemic RBCs was significantly increased compared with normal RBCs. Because in vitro enzyme activity does not necessarily represent in vivo activity, we measured the rate of metHb reduction in intact RBCs. Intact thalassemic RBCs demons...
متن کاملStudies on the Oxidation-reduction of Hemoglobin and Methemoglobin
Hemoglobin is oxidized to methemoglobin by products formed during the oxidation of a number of different substances. With some of these substances, both oxygen consumption and hemoglobin oxidation are accelerated by thermolabile constituents of pneumococci; with others of the easily oxidized substances, neither reaction seems to be influenced by the presence of the bacterial substances. The sam...
متن کاملEffect of organic phosphates on methemoglobin reduction by ascorbic acid.
The rate of methemoglobin reduction by ascorbic acid was accelerated in the presence of ATP,2,3-diphosphoglycerate (2,3-DPG), and inositol hexaphosphate (IHP). The acceleration was as much as three times, four times, and ten times in the presence of ATP, 2.3-DPG, and IHP at pH 7.0, respectively. The changes of the concentrations of methemoglobin and ascorbic acid during the methemoglobin reduct...
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ژورنال
عنوان ژورنال: Blood
سال: 1963
ISSN: 0006-4971,1528-0020
DOI: 10.1182/blood.v22.3.323.323