Derivatization of Aminoglycoside Antibiotics with Tris(2,6-dimethoxyphenyl)carbenium Ion.

Detection of aminoglycoside antibiotics by MS or HPLC is complicated, because a) carbohydrate molecules have low ionization ability in comparison with other organic molecules (particularly in MALDI-MS), and b) the lack of aromatics and/or amide bonds in the molecules makes common HPLC UV-detectors useless. Here, we report on the application of a previously developed method for amine derivatization with tris(2,6- dimethoxyphenyl)carbenium ion to selective modification of aminoglycoside antibiotics. Only amino groups bound to primary carbons get modified. The attached aromatic residue carries a permanent positive charge. This makes it easy to detect aminoglycoside antibiotics by MS-methods and HPLC, both as individual compounds and in mixtures.

[Synthesis and fluorescent properties of 5-(1-pyrenylethynyl)-2'- deoxyuridine-containing oligodeoxynucleotides]. / Sintez i fluorestsentnye svoistva 5-(1-pirenilétinil)-2'-dezoksiuridinsoderzhashchikh oligodezoksinukleotidov.

Novel reagents for the fluorescent labeling of oligo- and polynucleotides have been prepared: 5-(1-pyrenylethynyl)-2'-deoxyuridine 3'-phosphoramidite and a solid support carrying this nucleoside. Oligonucleotides containing one or several modified units have been synthesized, and the fluorescence of these probes has been shown to change upon hybridization with the complementary sequence.

[Fluorescence resonance energy transfer in the study of nucleic acids]. / Rezonansnyi perenos énergii fluorestsentsii vissledovanii nukelinovykh kislog.

Recent data are reviewed on the employment of fluorescence resonance energy transfer (FRET) in studying hybridization and higher structures of nucleic acids as well as their enzyme- and ribozyme-catalyzed reactions.

Conjugates of oligonucleotides with polyaromatic fluorophores as promising DNA probes.

Conjugates of pyrene and perylene with oligodeoxynucleotides were synthesized and tested as hybridisation probes. A 13-mer containing a 3-peryleneacetic acid residue attached to the 5' end through a hexamethylenediamine linker showed no response in the fluorescent spectrum upon hybridisation to the complementary sequence. At the same time, pyrene-labelled probes are sensitive to duplex formation. A pyrene pseudonucleotide unit based on 4-(1-pyrenyl)-1,3-butanediol can be introduced into any predetermined position(s) of the oligonucleotide chain. The probes polylabelled in this fashion displayed considerable changes in the excimer-to-monomer fluorescence intensity ratio after duplex formation. The internal location of two pyrene residues in the probe provides a drastic enhancement of excimer fluorescence (approximately 470 nm) upon hybridisation. When two pyrene units were brought into close proximity to two pyrenes in the complementary strand upon duplex formation, strong excimer emission at approximately 450 nm was detected. This effect provides a basis for a sensor construction designed to detect nucleic acid hybridisation.

[Novel reagent for labeling of biomolecules--activated derivative of pyrene dichromophore with excimeric fluorescence]. / Novyi reagent dlia mecheniia biomolekul--aktivirovannoe proizvodnoe pirenovogo bikhromofora s éksimernoi fluorestsentsiei.

N-[2-(1-pyrenyl)ethyl]-1-pyrenylacetamide, bis[2-(1-pyrenyl)ethyl]amine, and N,N-bis[2-(1-pyrenyl)ethyl]succinamide were synthesized from 1-pyrenylacetic acid. These compounds contain adjacent pyrene residues and display excimer fluorescence. The latter compound, as a pentafluorophenyl ester, was used to prepare fluorescently labeled oligodeoxyribonucleotide (5)CAGGAAACAGCTATGAC. For N,N-bis[2-(1-pyrenyl)ethyl]succinamide, the excimer-to-monomer fluorescence ratio and intensity of fluorescence in water-methanol solutions changed in the presence of single-stranded and double-stranded oligonucleotides, upon attachment to an oligonucleotide, and upon hybridization of the resulting conjugate with the complementary nucleotide sequence.