新型[12]aneN3衍生物的合成及对磷酸二酯的催化降解

利用叠氮与端基炔在铜(Ⅰ)催化下的高效Click反应制备了3,5-二.甲基苯甲酸甲酯衍生的单和双[12]aneN3化合物4a和4b,并对其进行了核磁共振、红外光谱、元素分析和高分辨质谱表征.动力学实验表明,相应的单核和双核锌(Ⅱ)配合物在甲醇介质中能够有效催化RNA模型磷酸二酯2-羟丙基对硝基苯基磷酸二酯(HPNPP)...     

A label-free, quadruplex-based functional molecular beacon (LFG4-MB) for fluorescence turn-on detection of DNA and nuclease

We demonstrate a novel concept for the construction of a label-free, quadruplex-based functional molecular beacon (LFG4-MB) by using G-quadruplex motif as a substitute for Watson-Crick base pairing in the MB stem and a specific G-quadruplex binder, N-methyl mesoporphyrin IX (NMM) as a reporter. It shows high sensitivity in assays for UDG activity/inhibition and detection of DNA sequence based on the unique fluorescence increase that occurs as a result of the strong interaction between NMM and the folded quadruplex upon removal of uracil by UDG or displacement of block sequence by target DNA. The LFG4-MB is simple in design, fast in operation and could be easily transposed to other biological relevant target analysis by simply changing the recognition portion. The LFG4-MB does not require any chemical modification for DNA, which offers the advantages of simplicity and cost efficiency and obviates the possible interference with the affinity and specificity of the MB as well as the kinetic behavior of the catalysts caused by the bulky fluorescent groups. More importantly, the LFG4-MB offers great extent of freedom to tune the experimental conditions for the general applicability in bioanalysis.     

Benzylidene acetal type bridged nucleic acids: changes in properties upon cleavage of the bridge triggered by external stimuli

Four classes of benzylidene acetal type bridged nucleic acids (BA-BNAs) were designed with 2',4'-bridged structures that cleaved upon exposure to appropriate external stimuli. Cleavage of 6-nitroveratrylidene and 2-nitrobenzylidene acetal type BNA bridges occurred upon photoirradiation and subsequent treatment with thiol caused changes in secondary structure to afford 4'-C-hydroxymethyl RNA. Benzylidene and 4-nitrobenzylidene acetal type BNA responded to acids and reducing agents, respectively, resulting in hydrolysis of the acetal-bridged structure. Cleavage of the bridge removed sugar conformational restrictions and changed the duplex- and triplex-forming properties of the BNA-modified oligonucleotides. Moreover, oligonucleotides incorporating a single BA-BNA modification had considerably improved stability toward 3'-exonuclease, which was lost upon cleavage of the bridge. Thus, these new BNAs may be useful as therapeutic and detection tools by sensing various environments.