An efficient method for the site-specific 99mTc labeling of nanobody

作     者：Qi Luo Hannan Gao Jiyun Shi Fan Wang 

作者机构：Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory) Medical Isotopes Research Center and Department of Radiation MedicineState Key Laboratory of Natural and Biomimetic DrugsSchool of Basic Medical SciencesPeking University Key Laboratory of Protein and Peptide PharmaceuticalsCAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of Sciences Beijing Translational Center for Biopharmaceuticals 

出 版 物：《Biophysics Reports》 (生物物理学报)

年 卷 期：2021年第7卷第4期

页      面：295-303页

核心收录：

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 

基　　金：supported by National Natural Science Foundation of China (81630045,81927802 and 81971676) Emergency Key Program of Guangzhou Laboratory (EKPG21-16) 

主　　题：Nanobody Sortase A Site-specific radiolabeling 99mTc 

摘      要：Recently, there has been a lot of interest by using nanobodies（heavy chain-only antibodies produced naturally from the Camelidae） as targeting molecules for molecular imaging, especially for the nuclear medicine imaging. A radiolabeled method that generates a homogeneous product is of utmost importance in radiotracer development for the nuclear medicine imaging. The conventional method for the radiolabeling of nanobodies is non-specifically, which conjugates the radioisotope chelating group to the side chain ε-amine group of lysine or sulfhydryl of cysteine of nanobodies, with a shortcoming of produce of the heterogeneous radiotracer. Here we describe a method for the site-specific radioisotope;99m;Tc labeling of nanobodies by transpeptidase Sortase A. The radiolabeling process includes two steps: first step, NH;2;-GGGGK（HYNIC）-COOH peptide（GGGGK = NH;2;-Gly-Gly-Gly-Gly-Lys-COOH, HYNIC =6-hydrazinonicotinyl） was labeled with;99m;Tc to obtain GGGGK-HYNIC-;99m;Tc; second step, Sortase A catalyzes the formation of a new peptide bond between the peptide motif LPETG（NH;2;-Leu-Pro-GluThr-Gly-COOH） expressed C-terminally on the nanobody and the N-terminal of GGGGK-HYNIC-;99m;*** a simple purification process, homogeneous single-conjugated and stable;99m;Tc-labeled nanobodies were obtained in 50% yield. This approach demonstrates that the Sortase A-mediated conjugation is a valuable strategy for the development of site-specifically;99m;Tc-labeled nanobodies.