Exploring the potential of the vitamin B < sub > 12 < /sub > derivative azidocobalamin to undergo Huisgen 1,3-dipolar azide-alkyne cycloaddition reactions

J Inorg Biochem. 2024 Feb 10;254:112504. doi: 10.1016/j.jinorgbio.2024.112504. Online ahead of print.ABSTRACTThere is considerable interest in using the metalloprotein cofactor vitamin B12 as a vehicle to deliver drugs and diagnostic agents into mammalian or bacterial cells by exploiting the B12-specific active uptake pathways. Conjugation of the cargo via the β-axial site or the 5'-OH of the ribose of the nucleotide are the most desirable sites, to maximise intracellular uptake. Herein we show the potential of conjugation at the beta-azido ligand of the vitamin B12 derivative azidocobalamin via a click-type azide-alkyne 1,3-dipolar cycloaddition (Huisgen cycloaddition) reaction. Reacting azidocobalamin with dimethyl acetylenedicarboxylate at 40 °C results in essentially stoichiometric conversion of azidocobalamin to the corresponding triazolato complex. The stability of the complex as a function of pH and in the presence of cyanide were investigated. The complex is stable in pD 7.0 phosphate buffer for 24 h. The rate of beta-axial ligand substitution was found to be one order of magnitude slower for the triazolatocobalamin complex compared with azidocobalamin.PMID:38412777 | DOI:10.1016/j.jinorgbio.2024.112504
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Source Type: research