首页|An efficient method for the site-specific 99mTc labeling of nanobody
An efficient method for the site-specific 99mTc labeling of nanobody
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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 impor-tance 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 radioiso-tope 99mTc labeling of nanobodies by transpeptidase Sortase A.The radiolabeling process includes two steps:first step,NH2-GGGGK(HYNIC)-COOH peptide (GGGGK =NH2-Gly-Gly-Gly-Gly-Lys-COOH,HYNIC =6-hydrazinonicotinyl) was labeled with 99mTc to obtain GGGGK-HYNIC-99mTc;second step,Sortase A catalyzes the formation of a new peptide bond between the peptide motif LPETG (NH2-Leu-Pro-Glu-Thr-Gly-COOH) expressed C-terminally on the nanobody and the N-terminal of GGGGK-HYNIC-99mTc.After a simple purification process,homogeneous single-conjugated and stable 99mTc-labeled nano-bodies were obtained in ＞50％ yield.This approach demonstrates that the Sortase A-mediated conjuga-tion is a valuable strategy for the development of site-specifically 99mTc-labeled nanobodies.
NanobodySortase ASite-specific radiolabeling99mTc
Qi Luo、Hannan Gao、Jiyun Shi、Fan Wang
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Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory),Guangzhou 510005,China
Medical Isotopes Research Center and Department of Radiation Medicine,State Key Laboratory of Natural and Biomimetic Drugs,School of Basic Medical Sciences,Peking University,Beijing 100191,China
Key Laboratory of Protein and Peptide Pharmaceuticals,CAS Center for Excellence in Biomacromolecules,Insti-tute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China
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