Relationship between Age and Enzymatic Activities in Human Erythrocytes from Normal and Fava Bean-sensitive Subjects* (original) (raw)
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Scandinavian journal of haematology, 1984
Complete removal of leucocytes and platelets from erythrocytes and the development of a sensitized procedure for the assay of G6PD activity allowed the biochemical mechanisms of the Mediterranean variety of G6PD deficiency to be re-evaluated. Activity in the young erythrocytes from 9 G6PD-deficient subjects averaged 0.1% of the levels observed in the corresponding erythrocyte fraction from normal individuals: moreover, the decline of activity during aging of the G6PD-deficient erythrocytes was comparable with that observed for the normal enzyme. Mutant G6PD purified from granulocytes of a G6PD-deficient subject and entrapped within the corresponding erythrocytes was remarkably stable. Exposure of native erythrocytes to an oxidative stress (divicine plus ascorbate) resulted in a decrease of G6PD activity that was significantly more rapid and extensive in control than in G6PD-deficient cells. These results seem to exclude enhanced intracellular breakdown of the mutant protein within t...
Colombia Medica, 2007
Glucose-6-phosphate dehydrogenase is the first enzyme in the pentose phosphate pathway and the main intracellular source of reduced nicotidamineadenine nucleotidephosphate (NADPH), involved in diverse physiological processes such as antioxidant defense, (for instance in the erythrocyte) endothelial growth modulation, erithropoyesis, vascularization and phagocitosis. G6PDH deficiency is the most common X-chromosome-linked enzymopathy in human beings. Although it is present in any type cell, its absolute deficiency is incompatible with life. According to WHO, 400 million people are affected by G6PD deficiency in the world but in Colombia, the severe form prevalence is about 3% to 7%. There are no data related to slight and moderate alterations, that also have clinical effects. This paper reviews some G6PD biomolecular aspects, its classification according to activity and electrophoretic mobility, as well as some main clinical aspects related to its activity alteration.
European Journal of Pediatrics, 2009
Introduction Reduced concentrations of glucose-6-phospate dehydrogenase (G6PD) render erythrocytes susceptible to hemolysis under conditions of oxidative stress. In favism, the ingestion of fava beans induces an oxidative stress to erythrocytes, leading to acute hemolysis. Discussion The simultaneous occurrence of methemoglobinemia has been reported only scarcely, despite the fact that both phenomena are the consequence of a common pathophysiologic mechanism. The presence of methemoglobinemia has important diagnostic and therapeutic consequences. We report a previously healthy boy who presented with combined severe hemolytic anemia and cyanosis due to methemoglobinemia, following the ingestion of fava beans. His condition was complicated by the development of transient acute renal failure. A G6PD-deficiency was diagnosed. We review the literature on the combination of acute hemolysis and methemoglobinemia in favism. Pathophysiologic, diagnostic, and therapeutic aspects of this disorder are discussed.
Iubmb Life, 1996
The levels of reduced glutathione in severe glucose-6-phosphate dehydrogenase deficient red blood cells,were found, when assayed immediately after blood withdrawing, almost equal to those of normal human erythroeytes. On the contrary, if the blood samples were stored at 4°C for 4 days (or more) either as whole blood or as washed erythrocytes with or without glucose, the glutathione concentration of the enzyme-deficient cells decreased to half the initial value. After a mild t-butylhydroperoxide (!-BHP) treatment, only glucose-6-phosphate dehydrogenase deficient red cells exhibited a drastic decrease ofglutathione, the normal ones being almost unaffected. If!-BI-IP-treated erythrocytes were incubated in the presence &glucose or of oxidized glutathione, a full recovery of the inital glutathione concentration was detected only in normal samples. Glucose could not be replaced by any other sugar. When the oxidative stress was induced by addition of methylene blue (MB), the behaviour was similar but less marked; it was however impossible, in this case, to restore the normal glutathione levels, through a subsequent incubation &the MB-treated erythrocytes with oxidized glutathione. This discrepancy can be explained by the finding that a marked inhibition ofglutathione reductase was observed in MB-treated erythrocytes, while/-BHP exposure had no direct effect on this enzyme.
Transfusion Medicine and Hemotherapy, 2012
G6PD catalyzes the first, pace-making reaction of pentosephosphate cycle (PPC) which produces NADPH. NADPH maintains glutathione and thiol groups of proteins and enzymes in the reduced state which is essential for protection against oxidative stress. Individuals affected by G6PD deficiency are unable to regenerate reduced glutathione (GSH) and are undefended against oxidative stress. G6PD deficiency accelerates normal senescence and enhances the precocious removal of chronologically young, yet biologically old cells. The term hemolytic anemia is misleading because RBCs do not lyse but are removed by phagocytosis. Acute hemolysis by fava bean ingestion in G6PD deficient individuals (favism) is described being the beststudied natural model of oxidant damage. It bears strong analogies to hemolysis by oxidant drugs or chemicals. Membrane alterations observed in vivo during favism are superimposable to changes in senescent RBCs. In summary, RBC membranes isolated from favic patients contained elevated amounts of complexes between IgG and the complement fragment C3b/C3c and were prone to vesiculation. Anti-band 3 IgG reacted to aggregated band 3-complement complexes. In favism extensive clustering of band 3 and membrane deposition of hemichromes were also observed. Severely damaged RBCs isolated from early crises had extensive membrane cross-bonding and very low GSH levels and were phagocytosed 10-fold more intensely compared to normal RBCs. Schlüsselwörter G6PD • G6PD-Defizienz • Band 3 • Hämolyse • Favismus Zusammenfassung G6PD katalysiert die erste geschwindigkeitsbestimmende Reaktion des Pentosephosphat-Zyklus (PPC), über den NADPH produziert wird. NADPH sorgt dafür, dass die Glutathion-und Thiol-Gruppen von Proteinen und Enzymen im reduzierten Status bleiben, was essentiell für den Schutz gegen oxidativen Stress ist. Personen, die von einer G6PD-Defizienz betroffen sind, sind nicht in der Lage, reduziertes Glutathion (GSH) zu regenerieren und so ungeschützt gegen oxidativen Stress. Die G6PD-Defizienz beschleunigt die normale Alterung und erhöht die frühzeitige Entfernung von chronologisch jungen, biologisch aber alten Zellen. Der Begriff hämolytische Anämie ist irreführend, da die Erythrozyten nicht lysiert, sondern durch Phagozytose entfernt werden. Eine akute Hämolyse durch Favabohnenverzehr bei G6PD-defizienten Personen (Favismus) ist als das beststudierte natürliche Modell einer oxidativen Schädigung bekannt. Sie weist große Ähnlichkeiten mit einer durch oxidierende Medikamente oder Chemikalien verursachte Hämolyse auf. Während des Favismus in vivo beobachtete Membranänderungen sind mit denen von alten Erythrozyten deckungsgleich. Zusammenfassend ist festzustellen, dass Erythrozytenmembranen, die von Favismus-Patienten isoliert wurden, erhöhte Anteile von Komplexen zwischen IgG und dem Komplementfragment C2b/C3c enthalten und zur Vesikulation neigen. Anti-Band-3-IgG reagieren mit den aggregierten Band-3-Komplement-Komplexen. Bei Favismus ist eine extensive Cluster-Bildung des Band-3-Pro teins zu beobachten, darüber hinaus treten Membranablagerungen von Hemichromen auf. Schwer geschädigte Erythrozyten, die während früher Krisen isoliert wurden, zeigen ein extensives «membrane cross-binding» und niedrige GSH-Gehalte und werden zehnfach häufiger phagozytiert als normale Erythrozyten.
In vitro correction of erythrocyte glucose 6-phosphate dehydrogenase (G6PD) deficiency
Archives of Biochemistry and Biophysics, 1979
A high-yield procedure based on hypotonic lysis and isotonic resealing of erythrocytes was used in order to achieve entrapment of homogeneous human glucose g-phosphate dehydrogenase and of other metabolically related enzyme proteins (hexokinase and 6-phosphogluconate dehydrogenase). Erythrocytes from normal subjects and from individuals affected by glucose 6-phosphate dehydrogenase deficiency (glucose 6-phosphate dehydrogenase Mediterranean) were used for such studies. The following properties of the variously loaded erythrocyte suspensions were investigated: (a) hexose monophosphate shunt activity, (b) glycolytic activity, (c) intracellular concentrations of glucose 6-phosphate, 6phosphogluconate, NADP, and NADPH. These parameters were evaluated on the erythrocyte suspensions both in the resting state and under oxidative stimulation by methylene blue. In the glucose g-phosphate dehydrogenase-deficient cells, complete normalization of hexose monophosphate shunt activity and of the other metabolic properties under study was achieved by restoring the intracellular glucose 6-phosphate dehydrogenase activity up to the levels of normal erythrocytes. Specifically, hexokinase became the rate-limiting step of the overall glucose oxidation pathway under methylene blue stimulation, this reproducing the situation found in normal erythrocytes. The extent of Heinz bodies formation upon incubation with acetylphenylhydrazine confirmed the full metabolic competence of the glucose 6-phosphate dehydrogenase-reconstituted Mediterranean erythrocytes compared with the unloaded ones. 543