Autoradiograph of labeled purified bitiscetin and vWF-bound protein after SDS-(15%) PAGE. Labeled material was treated either nonreduced (lanes 1 and 2) or after reduction (lanes 3 and 4). Purified labeled bitiscetin (≠50,000 cpm/lane) was analyzed unreduced (lane 1) or after reduction (lane 3). ¹²⁵I-bitiscetin bound to immobilized vWF was extracted by incubating with 1% SDS, 0.125 mol/LTris-HCl buffer, pH 6.8. Recovered radioactivity (200,000 cpm) corresponding to 10 incubation wells were loaded (100,000 cpm/lane) either unreduced (lane 2) or after reduction (lane 4). Each labeled material was mixed with ≠1 μg/lane of cold bitiscetin as carrier. Position of the molecular weight markers is indicated on the left.