生物谷報(bào)道：在細(xì)胞核里有著記載遺傳信息的DNA（脫氧核糖核酸）,，日本大阪大學(xué)產(chǎn)業(yè)科學(xué)研究所真嶋哲朗教授（光化學(xué)）的研究小組研究出在DNA中電流流動(dòng)的情況。DNA的雙螺旋鏈的直徑大約在2納米左右,，利用這種納米級(jí)的“電線”,，可以制作出類似半導(dǎo)體的超微型電子設(shè)備。他們的研究成果發(fā)表在本周的《美國(guó)科學(xué)院學(xué)報(bào)》在線版上。
據(jù)朝日新聞報(bào)道,，研究揭示了在DNA中電流流通的可能性,，這一電子通道人們以前并不了解。真嶋教授的研究小組通過(guò)實(shí)驗(yàn),，首次確認(rèn)了電流并非在雙螺旋鏈通過(guò),，而是在兩條鏈中間的鹽基進(jìn)行傳導(dǎo)。
研究小組在人造玻璃襯底上鋪設(shè)了排列了10－100個(gè)鹽基的DNA片斷,。在一端使用光增感劑,，另一端放置熒光色素，玻璃襯底中間進(jìn)行紫外線照射,。于是,，從光增感劑那端產(chǎn)生正電荷，并向另一端移動(dòng)與熒光色素發(fā)生反應(yīng),，便能觀測(cè)到熒光消失的現(xiàn)象,。根據(jù)4種鹽基排列的順序不同，電流流動(dòng)的速度也會(huì)發(fā)生改變,。（引自中國(guó)公眾科技網(wǎng)）
原始出處:
Published online before print June 25, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0700795104
Chemistry
Biochemistry
Single-molecule observation of DNA charge transfer
( electron transfer | single-molecule fluorescence | SNP detection )
Tadao Takada, Mamoru Fujitsuka, and Tetsuro Majima *
The Institute of Scientific and Industrial Research (SANKEN), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
Edited by Jacqueline K. Barton, California Institute of Technology, Pasadena, CA, and approved May 21, 2007 (received for review January 29, 2007)
DNA charge transfer highly depends on the electronic interaction between base pairs and reflects the difference in the base composition and sequence. For the purpose of investigating the charge transfer process of individual DNA molecules and the optical readout of DNA information at the single-molecule level, we performed single-molecule observation of the DNA charge transfer process by using single-molecule fluorescence spectroscopy. The DNA charge transfer process, leading to the oxidation of the fluorescent dye, was explored by monitoring the on-off signal of the dye after the charge injection by the excitation of a photosensitizer. The photobleaching efficiency of the dyes by the DNA charge transfer specifically depended on the base sequence and mismatch base pair, demonstrating the discrimination of the individual DNA information. Based on this approach, the optical readout of a single-base mismatch contained in a target DNA was performed at the single-molecule level.
Fig. 1. DNA charge transfer detection system. (a) Photobleaching of the fluorescent dyes by DNA charge transfer. The NI and fluorescent dye (Fl) are represented by blue and red, respectively. The fluorescent dye is oxidized when the charge can freely migrate through DNA, leading to the photobleaching of the dyes. In the presence of the mismatch site, the charge transfer to the dyes is inhibited. (b) The positive charge injection (hole) process via A-hopping and the following charge transfer to the reporter fluorophore. Excitation of NI by UV light generates NI in the singlet excited state, which oxidizes the adjacentAbase to give the contacted ion pair. The positive charge on theAbase escapes from the ion pair and migrates to the nearestGthrough hopping between A bases to provide the charge separated state with a long lifetime. The hole injected into DNA migrates to the fluorescent dye, leading to the irreversible reaction of the reporter fluorophore.
