COMPLEXATION OF URANIUM-VI WITH THE SIDEROPHORE PYOVERDINE

The complexation of uranyl ion by the bacterial siderophore pyoverdine A in aqueous solution has been monitored with the aid of UV-visible s pectroscopy. The complexing molecule was employed either in intact for m or in a partially modified state by the action of laser illumination prior to complexation. In both cases, models were developed which too k into account hydrolysis of uranium and permitted an excellent fit wi th the experimental data. The complexation constants are K-1 = (8.2 +/ - 0.5) . 10(-4) M in the case of unmodified pyoverdine and K'(1) = (2. 0 +/- 0.3) . 10(-3) M for partially degraded pyoverdine.