cyanine-dye-3 and threoninol

We herein describe a novel in-stem molecular beacon (ISMB) containing multiple Cy3-quencher pairs on d-threoninol scaffolds in the stem region. The designed Cy3 derivative was not significantly quenched by the adjacent nucleobases, self-quenching of the fluorophore was minimal, and the fluorophore did not severely destabilize the duplex. Using newly designed Cy3, we synthesized ISMBs containing two Cy3 moieties. The signal to background ratio of the ISMB containing two Cy3 moieties was above 100, whereas that with one Cy3 was 30. A Cy3-derivative containing ISMB used in a fluorescence in situ hybridization (FISH) detected endogenous β-actin mRNA in fixed cells without need for washing procedures.

Topics: Actins; Amino Alcohols; Base Sequence; Butylene Glycols; Carbocyanines; Fluorescent Dyes; HeLa Cells; Humans; In Situ Hybridization, Fluorescence; Oligonucleotide Probes; RNA, Messenger

Asymmetric dye clusters with a single fluorophore (Cy3) and multiple quenchers (4'-methylthioazobenzene-4-carboxylate, methyl red, and 4'-dimethylamino-2-nitroazobenzene-4-carboxylate) were prepared. The dye and one-to-five quenchers were tethered through D-threoninol to opposite strands of a DNA duplex. NMR analysis revealed that the clusters with a single fluorophore and two quenchers formed a sandwich-like structure (antiparallel H-aggregates). The melting temperatures of all the heteroclusters were almost the same, although structural distortion should become larger, as the number of quenchers increased. An asymmetric heterocluster of a single fluorophore and two quenchers showed larger excitonic interaction (i.e., hypochromicity of Cy3), than did a single Cy3 and a single quencher. Due to the larger exciton coupling between the dyes, the 1:2 heterocluster suppressed the background emission more efficiently than the 1:1 cluster. However, more quenchers did not enhance quenching efficiency due to the saturation of exciton coupling with two quenchers. Finally, this asymmetric 1:2 heterocluster was introduced into the stem region of a molecular beacon (MB; also known as an in-stem MB) targeting the fusion site in the L6 BCR-ABL fusion gene. With this MB design, the signal/background ratio was as high as 68 due to efficient suppression of background emission resulting from the maximized excitonic interaction.

Topics: Amino Alcohols; Azo Compounds; Base Sequence; Butylene Glycols; Carbocyanines; Carboxylic Acids; DNA; Fluorescent Dyes; Genes, abl; Humans; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Conformation; Molecular Probes; Molecular Sequence Data; Nucleic Acid Denaturation; Organic Chemicals; Spectrometry, Fluorescence; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Temperature