Development of a new thiol-reactive prosthetic group for site-specific labeling of biomolecules with radioactive iodine. Issue 17 (15th September 2018) - Shim, Ha Eun
Graphical abstract: Highlights: 125 I-labeled MSTP was synthesized in high radiochemical yield and radiochemical purity. Purified 125 I-labeled MSTP showed highly selective reactivity for thiol groups. 125 I-labeled MSTP were efficiently reacted with free cysteine containing biomolecules. Abstract: In this report, we describe the radiosynthesis of a new thiol-targeting prosthetic group for efficient radioactive iodine labeling of biomolecules. Radioiodination using the precursor 3 was performed to obtain 125 I-labeled tetrazole 4b with high radiochemical yield (73%) and radiochemical purity. Using the radiolabeled 4b, a single free cysteine containing peptide and human serum albumin were labeled with 125 I in modest-to-good radiochemical yields (65–99%) under mildly reactive conditions. A biodistribution study of [ 125 I]7 in normal ICR mice exhibited lower thyroid uptake values than those of 125 I-labeled human serum albumin prepared via a traditional radiolabeling method. Thus, [ 125 I]7 could be employed as an effective radiotracer for molecular imaging and biodistribution studies. The results clearly demonstrate that 4b has the potential to be effectively implemented as a prosthetic group in the preparation of radiolabeled biomolecules.