A New Bifunctional Chelator Enables Facile Biocoupling and Radiolabeling as the Basis for a Bioconjugation Kit

• Published in: Chembiochem : a European journal of chemical biology 2014-05, Vol.15 (7), p.986-994
• Main Authors: Barandov, Ali, Grünstein, Dan, Apostolova, Ivalaya, Buchert, Ralph, Roger, Michel, Brenner, Winfried, Abram, Ulrich, Seeberger, Peter H.
• Format: Article
• Language: English
• Subjects: Animals; bioconjugation; carbohydrates; Chelating Agents - chemistry; chelator; Crystallography, X-Ray; Galactose - chemistry; Glycoconjugates - chemical synthesis; Glycoconjugates - chemistry; Glycoconjugates - pharmacokinetics; Isotope Labeling; Mice; Mice, Inbred BALB C; Molecular Conformation; Organotechnetium Compounds - chemistry; radiolabeling; Solvents - chemistry; technetium-99m; Tissue Distribution; Tomography, Emission-Computed, Single-Photon; Triazoles - chemistry
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.201400001

A new tridentate bifunctional chelator, N‐(‐2‐picolyl)(‐4‐hydroxy)(‐3‐amino)benzoic acid (PHAB), was designed to efficiently coordinate the [99mTc(CO)3]+ core and facilitate coupling reactions to biomolecules. The chelator can be procured in the form of the corresponding benzotriazole ester (PHAB‐OBT), which can be stored and used as a bioconjugation kit. PHAB‐OBT reacts with modified carbohydrates with high selectivity and efficiency in a single step in both aqueous and organic media. As is desirable for a kit, no complicated chemical bench work is required. Glycoconjugate postlabeling resulted in neutral radiolabeled glycans with high radiochemical yields. Prelabeling approaches were assessed by successive reaction of PHAB‐OBT with the [99mTc(CO)3]+ core and a modified galactose model. The radiolabeled galactose was obtained in 84 % yield as defined by HPLC analysis. Biodistribution of the radioactive 99mTc‐labeled chelator, as well as the glycoconjugates, were examined in mice. Noticeably different biodistribution patterns were observed that reflect trends in the uptake of carbohydrate analogues by various organs. Bioconjugation kit: We present a facile biocoupling approach using a new tridendate bifunctional chelator that enables synthesis of glycoconjugates in a single step with high yields and short preparation time. Radiolabeled carbohydrates were achieved in both pre‐ and postlabeling fashion by using this approach.