RESUMO
We have designed and synthesized rotaxanes whose rates of rocking motion (pendular motion) were switched reversibly through changes to the size of the ring component in response to external stimuli. The ring molecules of the rotaxanes incorporate a metaphenylene unit, which swings like a pendulum, and a dianthrylethane unit, which undergoes reversible isomerization in response to photo- and thermal stimuli and changes the size of the ring component. The rocking rates were estimated quantitatively by variable-temperature (VT) NMR spectroscopy and saturation transfer experiments, which revealed substantial changes in the rates between the open and closed forms, particularly in the case of rotaxanes with an isopropoxy group attached to a phenylene unit.
RESUMO
Design, synthesis, and demonstration of a prototype of a shuttling molecular machine with a reversible brake function are reported. It is a photochemically and thermally reactive rotaxane composed of a dianthrylethane-based macrocycle as the ring component and a dumbbell shaped molecular unit with two, secondary ammonium stations separated by a phenylene spacer as the axle component. The rate of shuttling motion was shown to be reduced to less than 1 % (from 340 to <2.5 s(-1)) by reducing the size of the ring component from 30-crown-8 to 24-crown-8 macrocycles upon photoirradiation. The ring component was turned back to 30-crown-8 by thermal ring opening, thus establishing a reversible brake function that works in response to photochemical and thermal stimuli.
RESUMO
A concept and demonstration of a switching in frequencies of molecular motions are described using a pseudorotaxane system. The setup consists of dibenzylammonium hexafluorophosphate and a photochromic dianthrylethane-based [24]crown-8-type macrocycle, which we designed as a key ring component for the pseudorotaxane system having photocontrollable threading functionality by changing the size of ring component due to the action of light.
RESUMO
A long RNA oligomer, a 110mer with the sequence of a precursor-miRNA candidate, has been chemically synthesized in a single synthesizer run by means of standard automated phosphoramidite chemistry. The synthetic method involved the use of 2-cyanoethoxymethyl (CEM), a 2'-hydroxyl protecting group recently developed in our laboratory. We confirmed the identity of the synthetic 110mer by MALDI-TOF mass spectrometry, as well as HPLC, electrophoretic methods, RNase-digestion experiments, and its in vitro gene-silencing activity. The chemical synthesis of RNA oligomers of more than 100 nucleotides, which has until now been extremely difficult, can be practically realized by the CEM method.
Assuntos
Etil-Éteres/química , Éteres Metílicos/química , MicroRNAs/síntese química , Oligorribonucleotídeos/síntese química , Precursores de RNA/síntese química , Bioquímica/métodos , MicroRNAs/química , Oligorribonucleotídeos/química , Interferência de RNA , Precursores de RNA/químicaRESUMO
A long RNA oligomer, a 110mer with the sequence of a precursor-microRNA candidate, has been chemically synthesized in a single synthesizer run by means of standard automated phosphoramidite chemistry. The synthetic method involved the use of 2-cyanoethoxymethyl (CEM), a 2'-hydroxyl protecting group recently developed in our laboratory. We improved the methodology, introducing better coupling and capping conditions. The overall isolated yield of highly pure 110mer was 5.5%. Such a yield on a 1-mumol scale corresponds to 1 mg of product and emphasizes the practicality of the CEM method for synthesizing oligomers of more than 100 nt in sufficient quantity for biological research. We confirmed the identity of the 110mer by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, as well as HPLC, electrophoretic methods, and RNase-digestion experiments. The 110mer also showed sense-selective specific gene-silencing activity. As far as we know, this is the longest chemically synthesized RNA oligomer reported to date. Furthermore, the identity of the 110mer was confirmed by both physicochemical and biological methods.
Assuntos
Éteres/química , Inativação Gênica , MicroRNAs/síntese química , Nitrilas/química , Oligorribonucleotídeos/síntese química , Precursores de RNA/síntese química , Linhagem Celular , Cromatografia Líquida de Alta Pressão , Eletroforese Capilar , Humanos , MicroRNAs/química , MicroRNAs/isolamento & purificação , Oligorribonucleotídeos/química , Oligorribonucleotídeos/isolamento & purificação , Compostos Organofosforados/química , Precursores de RNA/química , Ribonucleosídeos/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
A novel method for the synthesis of RNA oligomers with 2-cyanoethoxymethyl (CEM) as the 2'-hydroxyl protecting group has been developed. The new method allows the synthesis of oligonucleotides with an efficiency and final purity comparable to that obtained in DNA synthesis.(1) In addition, the CEM method has the potential for application to the synthesis of very long RNA oligonucleotides.
Assuntos
Etil-Éteres/química , Éteres Metílicos/química , Oligorribonucleotídeos/síntese química , RNA/síntese química , Oligorribonucleotídeos/química , Compostos Organofosforados/síntese química , Compostos Organofosforados/química , RNA/químicaRESUMO
A novel method for the synthesis of RNA oligomers with 2-cyanoethoxymethyl (CEM) as the 2'-hydroxyl protecting group has been developed. The new method allows the synthesis of oligoribonucleotides with an efficiency and final purity comparable to that obtained in DNA synthesis. [structure: see text]