Naphthalene diimide derivative 1 carrying ferrocenyl moieties at the termini of imide substituents binds intact calf thymus DNA 4 times more strongly than denatured DNA, and its complex with dissociates 80 slowly that DNA. On basis these observations, ligand was applied to a probe electrochemical sensing. A thiol-linked single-stranded immobilized through S−Au bonding 20−30 pmol/mm2 on gold electrode. Following hybridization complementary electrode soaked in solution containing...

A novel potassium sensing oligonucleotide (PSO) was constructed by attaching fluorophores 6-FAM and 6-TAMRA to the 5'- 3'-termini of d(GGG TTA GGG GGG), respectively. The affinity PSO for K+ 43 000 times greater than that Na+, high enough selectivity enabling quantitation specifically in presence excess Na+. Fluorescence resonance energy transfer (FRET) from observed only K+. This phenomenon is based on approximation two upon formation a guanine quartet mediated Furthermore, fluorescent...

Ion probes: A potassium-sensing oligonucleotide with terminal pyrene moieties can be used as a fluorescent probe for the real-time monitoring of extracellular concentration K+ ions under physiological conditions. The excimer emission intensity (b) chair-type quadruplex structure formed depends on ion (0–200 mm), and differs significantly from that in absence potassium (a). Supporting information this article is available WWW http://www.wiley-vch.de/contents/jc_2002/2005/z501506_s.pdf or...

Toward the development of a universal, sensitive and convenient method DNA (or RNA) detection, electrochemically active oligonucleotides were prepared by covalent linkage ferrocenyl group to 5′-amino-hexyl-terminated synthetic oligonucleotides. Using these probes, we have been able demonstrate detection RNA at femtomole levels HPLC equipped with an ordinary electrochemical detector (ECD) [Takenaka,S., Uto,Y., Kondo,H., Ihara,T. Takagi,M. (1994) Anal. Biochem., 218, 436–443]. Thermodynamic...

Proteins recognize specific DNA sequences not only through direct contact between amino acids and bases, but also indirectly based on the sequence-dependent conformation deformability of (indirect readout).We used molecular dynamics simulations to analyze sequencedependent conformations all 136 possible tetrameric sandwiched CGCG sequences.The dimeric steps obtained by is consistent with that crystal structures.The simulation results further showed tetramers can highly depend flanking base...

Abstract Stereochemistry of the cycloadditions twenty-four heteroaromatic N-ylides with several symmetrically substituted cis and trans olefins has been investigated. Cyclic acyclic cycloadd to form ylides in a highly endo-selective manner giving almost quantitative yields stereospecific endo 3+2 cycloadducts. N-Ylides stabilized substituent carbonyl type react mostly two stereoisomeric cycloadducts anti ylides. In most cases, they undergo interconversion through retro cycloaddition process,...

Abstract Heating α-amino acids with a variety of carbonyl compounds generates N-unsubstituted or N-substituted azomethine ylides nonstabilized types through the elimination water and carbon dioxide. The are captured by olefinic, acetylenic, dipolarophiles producing pyrrolidines, pyrrolines, oxazolidines. reaction involves intermediary 5-oxazolidinones which can be sometimes isolated. Some synthetic equivalents parent ylide, methaniminium methylide, accessible this route.

Ligands that bind to and stabilize guanine-quadruplex (G4) structures regulate DNA replication have therapeutic potential for cancer neurodegenerative diseases. Because there are several G4 topologies, ligands their specific types may the ability preferentially of only certain genes. Here, we demonstrated binding stalled template at G4, depending on different topologies. For example, naphthalene diimide derivatives bound G-quartet with an additional interaction between ligand loop region a...

Crown ether linked DNA-intercalators have shown an enhanced binding ability to DNA in the presence of certain kinds metal ions, due a cationic property given by co-ordination crown moiety ions.

Spectroscopic studies revealed that ferrocenylnaphthalene diimide (1) can bind to tetraplex DNA at high potassium ion concentration. The was stabilized by the binding of 1, and this effect larger than any other stabilizers, which are known as a telomerase inhibitor. Quantitative analysis with circular dichroism quartz crystal microbalance strongly suggested 3:1 stoichiometry 1 DNA. telomere sequence could be extended substrate primer on surface an electrode proven increased current signal...

A new synthetic bis-9-acridinyl derivative containing a viologen linker chain binds strongly to DNA and shows typical cyclic voltammogram, indicating potential for use as reversible electochemical labelling agent DNA.

Abstract The dual‐labeled oligonucleotide derivative, FAT‐0, carrying 6‐ carboxyfluorescein (FAM) and 6‐carboxytetramethylrhodamine (TAMRA) labels at the 5′ 3′ termini of thrombin‐binding aptamer (TBA) sequence 5′‐GGT TGG TGT GGT TGG‐3′, its derivatives, FAT‐ n ( =3, 5, 7) with a spacer 5′‐end TBA T m A =2, 4, 6) have been designed synthesized. These fluorescent probes were developed for monitoring K + concentrations in living organisms. Circular dichroism, UV‐visible absorption,...

Abstract Regioselectivity and stereoselectivity of the cycloadditions heteroaromatic N-ylides with unsymmetrically-substituted olefins such as methyl-substituted cis olefins, an acrylate, related trans nitro other have been investigated. These are highly regioselective, while depends upon both electronic steric nature substituents ylide olefin. The 1-endo-2-exo cycloadducts anti form ylides which formed kinetically controlled products undergo isomerization into either syn through a retro...

An electrochemical method based on chronocoulometry coupled with hexaammineruthenium chloride (RuHex) is proposed for simple and rapid assay of telomerase without relying PCR gel electrophoresis. Thus, DNA extended by in extracts as small 5–1 000 HeLa cells the TS primer-immobilized electrodes was quantified successfully. This suitable quick screening drug candidates which inhibit telomerase. When 10 compounds were tested, multiplicity extension (x (TTAGGG)x) varied from 11 to 0, suggesting...

Cyclic naphthalene diimide 1 bound to hybrid-type tetraplex DNA from 5′-AGGG(TTAGGG)₃-3′ (<italic>K</italic> = 8.6 × 10⁶ M⁻¹) with 260-fold greater affinity than that when binding double stranded oligonucleotide consisting of 5′-GGG AGG TTT CGC-3′ and 3′-CCC TCC AAA GCG-5′ (<italic>nK</italic> 3.3 10⁴ 0.5 μM IC₅₀ for telomerase activity.

A cyclic naphthalene diimide (cyclic NDI, 1), carrying a benzene moiety as linker chain, was synthesized and its interaction with G-quadruplex DNAs of a-core a-coreTT human telomeric DNA, c-kit c-myc DNA sequence at promoter region, or thrombin-binding aptamer (TBA) studied based on UV-VIS circular dichroism (CD) spectroscopic techniques, thermal melting temperature measurement, FRET-melting assay. The spectra showed that 1 induced the formation different types structure. Compound bound to...

Abstract Condensation of 2-amino esters with carbonyl compounds leads to simple generation ester-stabilized azomethine ylides which are trapped by olefinic dipolarophiles as cycloadducts. Anti exclusively involved in the cycloadditions when N-substituted employed for ylide generation, while syn from N-unsubstituted esters. Relative stability among all possible isomers has been inspected and selective involvement particular ylidic forms explained on ground 1,5-dipole interaction or hydrogen...

BACKGROUND Telomerase is regarded as a good marker for cancer because it unregulated in most tumor cells compared with normal cells. We evaluated telomerase activity the lysate of tissue and surrounding oral patients by an electrochemical technique, dubbed assay (ECTA). METHODS The used ferrocenylnaphthalene diimide (FND) probe. Electrochemical substrate (ETS) primer immobilized on electrode was elongated FND bound to product give rise current. data were standardized change current before...

When a biotinylated FRET probe based on peptide–thrombin binding aptamer conjugate was introduced together with streptavidin and nuclear export signal peptide into HeLa cells, the resulting ternary complex enabled visualization of K+ concentration changes in cell.