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Methemoglobin. The structure of cytochrome b5 reductase, the enzyme that converts methemoglobin to hemoglobin. [1] Methemoglobin (British: methaemoglobin, shortened MetHb) (pronounced "met-hemoglobin") is a hemoglobin in the form of metalloprotein, in which the iron in the heme group is in the Fe 3+ (ferric) state, not the Fe 2+ (ferrous) of ...
Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. [2] Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). [2] Complications may include seizures and heart arrhythmias. [3][4]
In such cases, the enzyme methemoglobin reductase will be able to eventually reactivate methemoglobin by reducing the iron center. In adult humans, the most common hemoglobin type is a tetramer (which contains four subunit proteins) called hemoglobin A , consisting of two α and two β subunits non-covalently bound, each made of 141 and 146 ...
Methemoglobin is also formed in small quantities when the dissociation of oxyhemoglobin results in the formation of methemoglobin and superoxide, O 2 −, instead of the usual products. Superoxide is a free radical and causes biochemical damage, but is neutralised by the action of the enzyme superoxide dismutase.
Cytochrome-b5 reductase is a NADH -dependent enzyme that converts ferricytochrome from a Fe3+ form to a Fe2+ form. [1] It contains FAD and catalyzes the reaction: NADH + H + + 2 ferricytochrome b5 = NAD + + 2 ferrocytochrome b5. In its b5-reducing capacity, this enzyme is involved in desaturation and elongation of fatty acids, cholesterol ...
Blue baby syndrome. A cyanotic newborn, or "blue baby". Note the blue coloration of the fingertips. Blue baby syndrome can refer to conditions that cause cyanosis, or blueness of the skin, in babies as a result of low oxygen levels in the blood. This term has traditionally been applied to cyanosis as a result of:.
Fetal hemoglobin, or foetal haemoglobin (also hemoglobin F, HbF, or α2γ2) is the main oxygen carrier protein in the human fetus. Hemoglobin F is found in fetal red blood cells, and is involved in transporting oxygen from the mother's bloodstream to organs and tissues in the fetus. It is produced at around 6 weeks of pregnancy [1] and the ...
Hemoglobinemia (or haemoglobinaemia) is a medical condition in which there is an excess of hemoglobin in the blood plasma. This is an effect of intravascular hemolysis, in which hemoglobin separates from red blood cells, a form of anemia. Hemoglobinemia can be caused by intrinsic or extrinsic factors. When hemoglobinemia is internally caused ...