Intracellular Ferriprotoporphyrin IX Is
نویسندگان
چکیده
Human erythrocytes were treated with menadione to oxidatively denature hemoglobin and release ferriprotoporphyrin IX (ferriheme, FP) intracellularly. The high affinity of FP for chloroquine was used to detect its release. After incubation for 1 hr at 37’C and pH 7.4 with 0.5 mM menadione, erythrocytes bound 14C-chloroquine with an apparent dissociation constant of 1O M. Untreated erythrocytes did not bind chloroquine with high affinity. At a chloroquine concentration in the medium of 2 zM, for example, menadione-treated erythrocytes bound 70 mole chloroquine/kg and untreated erythrocytes bound 13.4 smoIe/kg. The intracellular location of FP released by menadione was verified by finding that Tween 80 did not prevent chloroquine binding. By contrast. Tween 80 inhib-
منابع مشابه
Effect of replacement of ferriprotoporphyrin IX in the haem domain of cytochrome P-450 BM-3 on substrate binding and catalytic activity.
Bacillus megaterium cytochrome P-450 BM-3 (coded by gene CYP102) is a catalytically self-sufficient mono-oxygenase, with both cytochrome P-450 and NADPH:cytochrome P-450 reductase domains, that catalyses the hydroxylation of fatty acids. The natural ferriprotoporphyrin IX has been removed from the haem domain of cytochrome P-450 BM-3 by treatment with acidified acetone, and it has been shown th...
متن کاملMechanism of hemolysis induced by ferriprotoporphyrin IX.
Incubation of a 0.5% suspension of washed, normal mouse erythrocytes with ferriprotoporphyrin IX (FP) at 37 degrees C and pH 7.4 caused potassium loss, swelling, increased susceptibility to hypotonic lysis, and finally hemolysis. Hemolysis was not inhibited by incubation in the dark, malonyldialdehyde was not produced, and various free radical scavengers had no effect on the hemolysis. Only the...
متن کاملIntracellular ferriprotoporphyrin IX is a lytic agent.
Human erythrocytes were treated with menadione to oxidatively denature hemoglobin and release ferriprotoporphyrin IX (ferriheme, FP) intracellularly. The high affinity of FP for chloroquine was used to detect its release. After incubation for 1 hr at 37 degrees C and pH 7.4 with 0.5 mM menadione, erythrocytes bound 14C-chloroquine with an apparent dissociation constant of 10(-6)M. Untreated ery...
متن کاملRegulation of human erythrocyte glyceraldehyde-3-phosphate dehydrogenase by ferriprotoporphyrin IX.
Erythrocyte glyceraldehyde-3-phosphate dehydrogenase (G3PD) is a glycolytic enzyme containing critical thiol groups and whose activity is reversibly inhibited by binding to the cell membrane. Here, we demonstrate that the insertion of ferriprotoporphyrin IX (FP) into the red cell membranes exerts two opposite effects on membrane bound G3PD. First, the enzyme is partially inactivated through oxi...
متن کاملHemolysis of mouse erythrocytes by ferriprotoporphyrin IX and chloroquine. Chemotherapeutic implications.
Incubation of a 0.5% suspension of washed normal mouse erythrocytes with ferriprotoporphyrin IX (FP) for 2.5 h at 37 degrees C and pH 7.4 results in sufficient membrane damage to produce hemolysis. A sigmoidal dose-response curve is followed with 50% hemolysis being produced by 4 microM FP. Complete hemolysis is produced by 6 microM FP. The hemolytic process has at least two phases: a lag phase...
متن کامل