RESUMEN
The ultrafast deactivation processes in the excited state of biomolecules, such as the most stable tautomers of guanine, forbid any state-of-the-art gas phase spectroscopic studies on these species with nanosecond lasers. This drawback can be overcome by grafting a chromophore having a long-lived excited state to the molecule of interest, allowing thus a mass-selective detection by nanosecond R2PI and therefore double resonance IR/UV conformer-selective spectroscopic studies. The principle is presently demonstrated on the keto form of a modified 9-methylguanine, for which the IR/UV double resonance spectrum in the CâO stretch region, reported for the first time, provides evidence for extensive vibrational couplings within the guanine moiety. Such a successful strategy opens up a route to mass-selective IR/UV spectroscopic investigations on molecules exhibiting natural chromophores having ultrashort-lived excited states, such as DNA bases, their complexes as well as peptides containing short-lived aromatic residues.
Asunto(s)
Guanina/análogos & derivados , Guanina/química , Teoría Cuántica , Espectrofotometría InfrarrojaRESUMEN
The structural properties of a DNA/RNA duplex having a pyrene residue at the 5' end of DNA and a G-rich single strand region at the 3' end of RNA were studied in detail. Fluorescence and ultracentrifugation analyses indicated the formation of a complex containing four DNA/RNA duplexes, which required a pyrene residue, G-rich sequence, RNA-type backbone, and high salt concentration.
Asunto(s)
ADN/química , Guanina/química , Pirenos/química , ARN/química , Secuencia de Bases , ADN/metabolismo , G-Cuádruplex , Conformación de Ácido Nucleico , ARN/metabolismo , Espectrometría de Fluorescencia , UltracentrifugaciónRESUMEN
Single- and double-stranded oligodeoxynucleotides (ODNs) incorporating both 2-aminopurine (2AP) and an indole-fused cytosine analog (PPI) were prepared and studied for their fluorescence properties. PPI and 2AP can be excited simultaneously by irradiation at 300 nm, with emission observed at 500 nm for PPI and 370 nm for 2AP. We demonstrated the utility of these properties in the dual fluorescence labeling of ODNs giving well-separated emission peaks. In addition, both of the fluorescence signals of a doubly modified ODN changed independently, reflecting the local duplex formation at the regions containing 2AP or PPI. Potential applications of this strategy for the dual fluorescence labeling of oligonucleotides with 2AP and PPI include monitoring local structure alterations of functional nucleic acids and the multiplex detection of biologically important nucleic acids.
Asunto(s)
2-Aminopurina/análogos & derivados , 2-Aminopurina/química , Citosina/análogos & derivados , Citosina/química , Indoles/química , Oligonucleótidos/química , Coloración y Etiquetado/métodos , Secuencia de Bases , Colorantes Fluorescentes , Imagen Molecular , Datos de Secuencia Molecular , Espectrometría de FluorescenciaRESUMEN
2'-O-[N-(4-Aminobutylcarbamoyl)]uridine (U(abcm)) was synthesized and incorporated into oligonucleotides. The oligonucleotides incorporating U(abcm) formed more stable duplexes with their complementary and mismatched RNAs than those containing 2'-O-carbamoyluridine (U(cm)). The stability of duplex with a U(abcm)-rG base pair showed higher thermostability than the duplex having unmodified U-rG base pair. The U(abcm) residue showed enhanced resistance to snake venome phosphodiesterase.
Asunto(s)
Oligonucleótidos/síntesis química , ARN/química , Uridina/análogos & derivados , Uridina/síntesis química , Animales , Emparejamiento Base , Cationes , Cromatografía de Fase Inversa , Estabilidad de Medicamentos , Humanos , Conformación de Ácido Nucleico , Hidrolasas Diéster Fosfóricas/metabolismo , Interferencia de ARN , Venenos de SerpienteRESUMEN
7-(Benzofuran-2-yl)-7-deazadeoxyguanosine ((BF)dG) was synthesized and incorporated into an oligodeoxynucleotide (ODN). The single-stranded ODN containing (BF)dG shows 91-fold fluorescence enhancement upon binding of single-strand DNA binding protein.