Closo-dodecaborate (2-) anion as a potential prosthetic group for attachment of astatine to proteins. Aspects of the labelling chemistry with Chloramine-T.

Closo-dodecaborate (2-) was proposed as a prosthetic group for direct label ling of proteins with At-211 for radionuclide therapy. Astatination of clos o-dodecaborate (2-) anion using Chloramine-T was studied, and the influence of pH, reaction time, amount of substrate and oxidant was determined. A ma ximum labelling yield of 55 - 75% was found in the pH range 7-8. A spontane ous astatination of closo-dodecaborate (2-) in the absence of Chloramine-T was also found, presumably due to generation of oxidising products from wat er radiolysis. Our results of indicate that derivatives of closo-dodecabora te (2-) anion may be used as prosthetic groups for direct labelling of prot eins.