大环配合物在核酸切割中的应用

核酸切割试剂的研究是化学和分子生物学中最为活跃的前沿领域之一.研究核酸切割试剂,不仅是因为对核酸酶催化机理进行深入了解之需,同时还因为人工核酸酶在基因治疗中有着诱人的前景.大环配合物的合成、结构及其对核酸的切割作用已有广泛的文献报道.本文综述了作为重要的核酸切割试剂的大环多胺配合物和氮杂冠醚配合物对核酸的切割作用及其规律性,并展望了今后的发展与应用方向.     

丝组二肽所含基团在其切割DNA反应中的作用

近 2 0年来 ,人工核酸切割试剂的研究一直是化学、生物化学和分子生物学中最为活跃的前沿领域之一[1,2 ] .人工核酸切割试剂可以在足迹技术和核酸高级结构的研究中用作高分辨率的化学探针 ,还可以用于合成定点切割试剂[3] .后者又被称为人工工具酶 ,是一种非常重要的分子生物学工具 ,在疾病的基因治疗、反义 PCR技术等领域中都具有重要的应用 .人工核酸切割试剂的切割机理主要有自由基机理和磷酸酯水解机理两大类 .相对于自由基机理 ,水解机理具有许多优点 ,使得水解型切割试剂具有更为广泛的应用 .对于 DNA,目前文献报道的水解型人工切…     

铜试剂在有机合成中的应用研究进展

铜试剂催化的偶联反应是直接构建碳 碳键最有效的方法之一。本文综述了铜试剂催化的偶联反应构筑六种碳 碳键的方法;重点阐述了铜试剂催化构筑C(SP²)-C(SP²)的研究进展,含分子间偶联和分子内偶联。参考文献44篇。     

低价钛促进的酮腈的分子内还原偶联反应

自二十世纪七十年代,McMurry等发现低价钛试剂能引起羰基化合物的还原偶联反应以来,低价钛试剂在有机合成中的应用越来越受到人们的重视,已经发现低价钛试剂能引起不少官能团化合物的还原偶联反应.我们最近几年发现低价钛试剂能引起一些α,β-不饱和化合物和多官能团化合物的还原偶联环化反应.本文报道一酮二腈的分子内还原偶联反应.     

两亲性大环多胺La(III)配合物的合成、表征及催化质粒DNA水解的研究

近年来,人工核酸切割试剂的研究一直是化学生物学、生物化学和分子生物学中最为活跃的前沿领域之一。最近的研究结果表明大环多胺金属配合物在磷酸二酯水解方面表现出独特的催化性能,能作为化学核酸酶有效的催化DNA和RNA的磷酸二酯键的水解[1-2]。尤其是电荷较高的金属阳离子形     

具有DNA切割功能的新型多聚酰胺/丝组缀合物

为得到具有核酸切割功能的人工核酸酶, 设计合成了一种新型多聚酰胺/丝组缀合物, 并研究了其DNA切割活性. 合成的目标化合物在pH=6.0的BR缓冲溶液中对pBR322 DNA切割活性的初步实验结果表明, 于37 ℃保温6 h后, pBR322 DNA基本上被完全从Form Ⅰ切割为Form Ⅱ, 保温36 h后, pBR322 DNA几乎被切割完全.     

新型氨基甲酸乙酯人工抗原的分析表征方法研究

采用1-(3-二甲氨基丙基)-3-乙基碳二亚胺方法合成氨基甲酸乙酯(Ethyl carbamate,EC)新型人工抗原.将衰减全反射红外光谱法(ATR-FTIR)应用于人工合成抗原的表征分析,并结合荧光光谱分析EC人工抗原的偶联效果以及载体蛋白质分子的二级结构变化;通过质谱结合紫外光谱、电泳方法进行人工抗原的系统表征,计算新型人工抗原中半抗原分子与载体蛋白质分子的偶联比.结果表明:合成路线合理,成功获得了氨基甲酸乙酯新型人工抗原.人工抗原分子的α-螺旋、β-折叠和β-转角结构与载体蛋白质分子相比含量发生变化,人工抗原的荧光相图满足线性型态变迁关系,符合“二态模型”.氨基甲酸乙酯人工抗原分析表征的红外衰减全反射方法、基质辅助激光解析飞行时间质谱法获得的检测结果与其它光谱方法、电泳方法表征结果一致,获得人工抗原的偶联比为15∶1～19∶1,EC新型人工抗原免疫小鼠抗血清的效价为1∶25600.     

低价钛试剂促进下2-(2-硝基苯基)咪唑与席夫碱的反应

在低价钛试剂作用下,以四氢呋喃为溶剂,研究了2-(2-硝基苯基)咪唑与席夫碱的分子间还原偶联反应.结果发现席夫碱中C-N键的断裂优于其与硝基的偶联成环,生成了5,6-二氢化咪唑并[1,2-c]喹唑啉.     

丝组二肽对DNA的切割作用的研究

近20年来,人工核酸切割试剂的研究一直是生物化学中最为活跃的前沿领域之一,研究人工核酸切割试剂的主要目的是合成定点切割试剂,后者是一种重要的分子生物学工具,在疾病的基团治疗、反义PCR技术等领域中有着重要的应用价值。此外,人工核酸切割试剂还可以在足迹技术和核酸高级结构的研究中用作高分辨率的化学探针。     

芳基氧化偶联试剂在天然活性成分联苯并环辛烯类木脂素合成中的应用进展

联苯并环辛二烯类木脂素是重要的一类天然产物,具有保肝等多种生物活性.近20余年来各国学者对其全合成研究进行了卓有成效的探索,尤其在芳基氧化偶联试剂的应用方面取得了很多进展.作者结合在该领域多年的工作积累,对分子内和分子间芳基氧化偶联试剂在联苯并环辛二烯木脂素合成中的应用及全合成研究的进展进行了综述,以便对同道起到参考与启发作用.最后提出了新的双片段合成拼接的设想.     

Modification of Cyclodextrins for Use as Artificial Enzymes

The magical powers of enzymes have been attributed to their ability to bind specific substrates and catalyze reactions of the bound substrate. Artificial enzymes synthetically mimic the binding and the catalytic site to produce molecules that are not only smaller in size but also potentially have similar activity to the real enzymes. The main objective of our research is to create artificial redox enzymes by using cyclodextrins as binding sites and attaching flavin derivatives as the catalytic site. We have developed a strategy to attach a catalytic site to cyclodextrin exclusively at the 2-, 3- or the 6-position. The evaluation of the artificial enzyme in which flavin is attached to the 2-position gives a 647-fold acceleration factor. Although this is modest compared to those of real enzymes (which can have acceleration factors of a trillion), the artificial enzymes allow us to understand the elements that contribute to the incredible catalytic power of enzymes.     

人工模拟酶的研究与应用进展

人工模拟酶具有性质稳定、易于制备、环境耐受性强等优点,在某种程度上解决了天然酶易失活、难制备的缺点。本文按照人工模拟酶的分类,综述对比了传统模拟酶与纳米材料模拟酶的研究现状,对人工模拟酶优缺点进行总结分析,并对其应用前景进行了展望。     

Comparison of rates of phosphotriester formation and sulphonation by coupling agents in oligodeoxyribonucleotide synthesis by the phosphotriester method

Rates of phosphotriester bond formation and amounts of sulphonation are compared for three popular coupling agents used in oligodeoxyribonucleotide synthesis by the phosphotriester approach.     

First observation of luminescence from tris(2,2'-bipyridine)ruthenium(II) triggered by anodic oxidation of oligodeoxyribonucleotide.

Anodic oxidation of oligodeoxyribonucleotide in an alkaline aqueous medium containing tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)3(2+)) was shown to cause luminescence around +1.3 V (vs. Ag/AgCl) with a maximal intensity at approximately 600 nm, possibly originating from Ru(bpy)3(2+) in the d-pi* triplet state. A pivotal initial stage in the light production path was postulated to be the anodic oxidation of 2-deoxyribose residue. This reaction seems to be available for the determination of sub-micromol dm(-3) levels of oligodeoxyribonucleotide.     

Preorganization boosts the artificial esterase activity of a self-assembling peptide

The creation of artificial enzymes to mimic natural enzymes remains a great challenge owing to the complexity of the structural arrangement of the essential amino acids in catalytic centers. In this study, we used the phosphatase-based enzyme-instructed self-assembly(EISA) to supervise artificial esterases' final structures and catalytic activities. We reported that peptide precursors containing different phosphorylation sites could preorganize into alternated nanostructures and undergo dephosphorylation in the presence of alkaline phosphatase(ALP) with variation in kinetic and thermodynamic profiles. Although identical self-assembly compositions were formed after dephosphorylation, precursors with more enhanced preorganized states tended to better promote ALP dephosphorylation, facilitate further self-assembly, and strengthen the catalytic activities of the final assemblies. We envisioned that our strategy would be useful for further construction and manipulation of various artificial enzymes with superior catalytic activities.     

A Selective Sulfide Oxidation Catalyzed by Heterogeneous Artificial Metalloenzymes Iron@NikA

Performing a heterogeneous catalysis with proteins is still a challenge. Herein, we demonstrate the importance of cross-linked crystals for sulfoxide oxidation by an artificial enzyme. The biohybrid consists of the insertion of an iron complex into a NikA protein crystal. The heterogeneous catalysts displays a better efficiency-with higher reaction kinetics, a better stability and expand the substrate scope compared to its solution counterpart. Designing crystalline artificial enzymes represents a good alternative to soluble or supported enzymes for the future of synthetic biology.     

PNA based artificial nucleases displaying catalysis with turnover in the cleavage of a leukemia related RNA model

Several peptide nucleic acid based artificial nucleases (PNAzymes) are designed to create a bulge in the target RNA, which is a short model of the leukemia related bcr/abl mRNA. The target RNA is cleaved by the PNAzymes with a half-life of down to 11 h (using a 1 : 1 ratio of PNA-conjugate to target) and only upon base-pairing with the substrate. The PNA based systems are also shown to act in a catalytic fashion with turnover of substrate and are thus the first reported peptide nucleic acid based artificial RNA-cleaving enzymes.     

Directed cleavage of RNA within an imperfect complementary complex by oligonucleotide—bleomycin A5 conjugates

It was demonstarted for the first time that RNA can be subjected to site-specific oxidative cleavage induced by the glycopeptide antibiotic bleomycin A₅ (Blm) covalently linked to the 3"-terminus of an oligodeoxyribonucleotide through two, three, or four residues of hexaethylene glycol phosphate (p-heg) _n . The oligonucleotide conjugate with bleomycin forms an imperfect complementary complex with the RNA to be cleaved (5"-prCGGAGUUGGAAAACAAUGAAAAGGCCCCCA/Blm-(p-heg) _n -3"-pdGCCTCACCTTTTGTTA). The cleavage occurs at the only nucleotide residue (U) preceding a one-nucleotide bulge in the RNA chain, which is formed due to imperfect complementarity between the oligodeoxyribonucleotide and the RNA to be cleaved.     

Insertion of two pyrene moieties into oligodeoxyribonucleotides for the efficient detection of deletion polymorphisms

For the detection of deletion polymorphisms, two pyrene moieties are tethered to an oligodeoxyribonucleotide (ODN) on both sides of the intervening base; one- and two-base deletions can be selectively detected by the strength of the excimer emission.     

Artificial redox enzymes. II. A computational chemistry study1

A computational chemistry study of the artificial redox enzyme synthesized by covalently attaching flavin to cyclodextrins explains some of its properties. Calculations indicate that the flavin moiety covalently attached to cyclodextrin is not within the cavity of cyclodextrin. This result is consistent with the UV-vis spectrum of the artificial enzyme. The calculations also indicate hydrogen bonds formed between the carbonyl groups of the catalytic functionality and the hydroxyl groups of cyclodextrin play a role in their most stable conformation. This explains the observed overall stability of these artificial enzymes compared to riboflavin. Electrostatic energies and solvation energies play a major role in the stability of the hosts and the orientation of guests included within the artificial enzymes. The rates of oxidation of various thiols catalyzed by the artificial enzyme can be explained by the relative distances between the sulfur atom of the substrates and C(4a) of the flavin moiety.