The synthesis of a carbon-14 labeled pegylated Adnectin™ for placental transfer studies in guinea pigs.

Adnectins™ are novel fibronectin-based proteins containing domains engineered to bind to targets of therapeutic interest. The molecular weights of adnectins are less than conventional monoclonal antibodies but larger than traditional small molecules. Until now, there has been no information on the placental transfer of adnectins. To assess placental permeability to adnectins in pregnant guinea pigs, a radiolabeled adnectin, ATI-1072, bound to polyethylene glycol through a [(14) C]Maleimide linker, was synthesized from [1,4-(14) C]Maleic acid. This publication describes the synthesis and analysis of PEG-[(14) C]Maleimide-adnectin ([(14) C]ATI-1072).