PEPTIDIC CONJUGATES COMPRISING POLYHISTIDINE SEQUENCE AND FREE CYSTEINE AND THEIR USES IN IMAGING

摘要

Bioconjugates for use in imaging are disclosed include a linker sequence fused to a polypeptide capable of binding a target in a biological system. The linker sequence is designed so that it is capable of being radiolabelled, e.g. with a complex comprising a radionuclide, via a free cysteine residue and the polyhistidine sequence in the label that are both capable of simultaneously binding to a complex comprising the radionuclide. These interactions can improve significantly the rate and effficiency of radiolabelling compared to either protein with the His-tag or the free cysteine alone. Optionally, the free cysteine residue provides a site which can be covalently bonded to a moiety such as a second label, in a site-specific manner.