Construction of glucose oxidase-loaded human erythrocytes: a model of oxidative cytotoxicity.
Human red blood cells were loaded with Glucose oxidase from Aspergillus niger by a standardized procedure of encapsulation involving transient hypotonic hemolysis followed by isotonic resealing. The amount of loaded enzyme activity, as evaluated by O2 consumption at 5 mM glucose, ranged from 40 to 75 mumoles O2/hr/ml of packed red cells at 37 degrees C. The red cells loaded with Glucose oxidase were found to behave as efficient glucose-consuming bioreactors. Moreover, at 5 mM glucose, no clear mechanism of H2O2-induced damage was apparent, with the exception of a significantly increased formation of methemoglobin (10% approximately) and of a several-fold stimulated intracellular rate of hexose monophosphate shunt activity, indicating glutathione peroxidase-mediated draining of reduced glutathione for removal of bursts of H2O2. The Glucose oxidase-loaded red cells represent a convenient model system for cytotoxicity studies aiming at clarifying the effects of intracellularly formed H2O2.
D001234:Aspergillus niger / Q000201:enzymology; D004908:Erythrocyte Inclusions / Q000201:enzymology*; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004913:Erythrocytes, Abnormal / Q000201:enzymology*; D005947:Glucose / Q000378:metabolism; D005949:Glucose Oxidase / Q000378:metabolism* / Q000633:toxicity; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000096:biosynthesis; D008954:Models, Biological; D010084:Oxidation-Reduction
D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D005947:Glucose