Interactions of adriamycin with a calcium binding site.
Terbium (Tb3+) luminescence has been used to investigate the interactions of adriamycin with a specific calcium binding protein, in the plasma membrane of GH3/B6 pituitary tumor cells. The luminescence intensity and lifetime of the Tb3+-GH3/B6 complex was quenched in the presence of adriamycin. According to Stern-Volmer analysis, the quenching of Tb3+-GH3/B6 luminescence was by both membrane bound adriamycin (Ka = 3.7 x 10(5) M-1) and free adriamycin (kq = 7.3 x 10(7) M-1 s-1). The data suggests that, the calcium binding site at the outer surface of the membrane is collisionally accessible to freely diffusing adriamycin; and, that the toxin receptor site is located near the bound metal ion.
Canada
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RG
Department of Physiology and Biophysics, Howard University College of Medicine, Washington, D.C. 20059.
Saway
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W
Thompson
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D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004317:Doxorubicin / Q000378:metabolism*; D007700:Kinetics; D008163:Luminescent Measurements; D010911:Pituitary Neoplasms / Q000378:metabolism; D013725:Terbium
D002135:Calcium-Binding Proteins; D013725:Terbium; D004317:Doxorubicin