Synthesis and luminescence properties of a trinucleotide–europium(III) complex conjugate

Abstract

Two trinucleotide conjugates of the macrocyclic ligand 1,4,7-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane are prepared. One contains only DNA (1) and the second is a chimeric RNA/DNA conjugate (2). The synthetic methodology used to prepare the trinucleotide macrocyclic ligand conjugates is based on the introduction of a convertible nucleoside which has an electrophilic function to facilitate the attachment of any nucleophilic ligand to the 5-position of the 3-nucleoside unit. The convertible nucleoside is first treated with the macrocyclic ligand, 1,4,7,10-tetraazacyclododecane, followed by alkylation of the three remaining amine groups to give a conjugated macrocyclic ligand with three pendent amide groups. Addition of an equivalent of EuCl3 to trinucleotide (1) or (2) yields the complexes Eu(1) and Eu(2), respectively. Studies using time-resolved and steady state direct excitation luminescence spectroscopy show that Eu(III) binds to the macrocyclic moiety in 1 and in 2. The excitation peak frequency for the 7Fo5Do transition and the unexpectedly low number of water ligands in Eu(1) and Eu(2) are consistent with additional interactions of the Eu(III) macrocycle with one of the phosphate diester groups. Studies show that Eu(2) undergoes cleavage at the uridine nucleotide. The unique point of attachment of the macrocyclic complex will enable the preparation of new lanthanide nucleic acid conjugates with useful properties.

Probing the Ion Binding Site in a DNA Holliday Junction Using Förster Resonance Energy Transfer (FRET)

“…A similar result is observed if Eu 3+ is titrated into a solution of the junction; however, at the concentrations used in this titration, both classes of binding are expected to occur ( Supplementary Material, Figure S7 ). The observed binding behavior was comparable to what had previously been reported for Eu 3+ binding to the hammerhead ribozyme [ 34 , 35 ] and other RNA–Eu 3+ complexes [ 36 , 37 ]. We cannot rule out the possibility; however, that we were not able to resolve a binding class with a different environment but similar energy levels.…”

“…This direct coordination to the DNA is in keeping with the exothermic binding reaction observed by ITC. In previous work, Eu 3+ was found to bind to an RNA GAAA tetraloop, with a similar slight dehydration of the ion (removal of one coordinated water molecule) upon binding [ 36 , 37 ].…”

Pd0-Catalyzed Methyl Transfer on Nucleosides and Oligonucleotides, Envisaged as a PET Tracer

“…Finally, even a slight increase of the proportion of H 2 O was not appropriate at all (entry 10). After the achievement of the procedure optimization on the monomeric substrates, the last step was to test our best conditions on the dinucleotide 4 synthesized as a 70/30 mixture of diastereomers according to the standard phosphoramidite method from the 5'C-substituted nucleoside from 1b [19,20].…”

Oligonucleotide Labelling Using a Fluorogenic “Click” Reaction with a Hemicarboxonium Salt

“…The ODN2 and ODN4 derivatives were obtained by automated synthesis according to the standard phosphoramidite technology [20]. The primary alkylamine function of ODN2 was generated by displacement of the bromine of the convertible nucleoside during the ammonia treatment for the cleavage and protective groups removal of the oligonucleotide [21,22].…”