烟酰胺腺嘌呤二核苷酸(NAD~+)类似物的合成及与NAD~+依赖型酶相互作用进展

烟酰胺腺嘌呤二核苷酸(NAD+)与NAD+依赖型酶间的相互作用在细胞氧化还原反应、能量代谢、信号转导过程中发挥着重要作用.NAD+依赖型酶利用共同的辅酶,它们之间相互作用规律受到越来越广泛的关注.主要针对NAD+类似物的合成及与NAD+依赖型酶相互作用研究的最新进展作一综述,包括NAD+类似物的合成及其与天然NAD+依赖型酶相互作用、NAD+与突变酶相互作用及NAD+类似物与突变酶相互作用.     

Hantzsch ester衍生物及其离子基N(C)-H键断裂能量及在其反应机理研究中的应用

NAD(P)H辅酶氧化还原反应模拟研究在生物有机化学中一直占有显著的位置。Hantzsch 1,4-二氢吡啶作为NAD(P)H辅酶的一种类似物,不仅在有机合成、医药、生化等方面,而且在辅酶NAD(P)H模拟反应研究中均具有广泛的应用^[1]。虽然Hantzsch 1,4-二氢吡啶与生物活性分子的反应已进行了大量的研究,但其反应机理即Hantzsch 1,4-二氢吡啶中1位N-H键和4位C-H键孰先孰后断裂仍存在较大争议。若能测得Hantzsch 1,4-二氢吡啶及其离子基中N-H和C-H键的断裂能,应能为阐释其反应机理提供有说服力的依据。     

辅酶Q9的合成

以辅酶Q0为起始原料,经Diels-Aider加成,缩合和逆Dicls-Alder分解反应,合成了辅酶Q10的类似物辅酶Q9,总收率61.9%.中间体和Q9的结构经1H NMR和EI-MS表征.     

烟酰型辅酶NAD(P)+和NAD(P)H再生的研究进展

大部分氧化还原酶的催化反应需要烟酰型辅酶NAD(P) 和NAD(P)H作为氧化剂或还原剂参与,由于氧化还原酶应用广泛而辅酶价格昂贵,使得辅酶再生逐渐成为研究热点.综述了近年来NAD(P) 和NAD(P)H酶法再生、电化学法及光化学法再生的研究进展,并介绍了各再生技术的应用和开发状况.     

纳米金颗粒/麦尔多拉蓝溶胶的合成及NADH传感器应用

1引言脱氢酶是氧化还原酶中为数最多的一类酶,目前已知超过300种脱氢酶使用氧化型烟酰胺腺嘌呤二核苷酸(NAD+)作为辅酶。在这些酶和辅酶协同作用催化底物时,NAD+从底物接受电子被还原成还原型烟酰胺腺嘌呤二核苷     

辅酶I在Co/CFUE上的电化学行为及应用

辅酶I(NAD )在0.005moL/LTris 0.01moL/LNaCl溶液(pH7.0)中,于钴离子注入修饰碳纤维电极上出现一个S形的还原波,半波电位为-1.45V(vs.SCE)。峰电流与NAD 的浓度在2.38×10-5～4.76×10-4mol/L(r=0 9992)和4.76×10-4～1.78×10-3mol/L(r=0.9982)之间成线性关系,检出限为1.19×10-5mol/L,回收率在96.7%～103.4%之间。用线性扫描、循环伏安法研究了钴离子注入修饰碳纤维电极上NAD 的电化学行为。电极反应机理为:NAD e NAD·;NAD· e H NADH;2NAD·→NAD2。另外,钴离子注入修饰碳纤维电极对NAD 具有电催化作用。     

Sirt1及Sirt2与活性分子INA的作用机制研究

应用分子模拟理论与方法研究了人类沉默信息调节因子2相关酶类Sirtuin家族成员Sirt1及Sirt2与一种活性分子(命名为INA)的作用机制.同源模建了Sirt1的三维结构,通过分子对接手段得到Sirt1(NAD+)-INA及Sirt2(NAD+)-INA的两种复合物体系,进行了分子动力学模拟.并且分别计算了两种体系中关键氨基酸残基与INA的结合自由能值,由此推测出Sirt1(NAD+)-INA、Sirt2(NAD+)-INA体系结合位点分别为Val72,Ser73和Arg272及Phe235,Leu264和Gly305,确证了两种体系的结合模式.模拟结果表明,在Sirt1(NAD+)-INA体系中,INA与催化底物NAD+距离较近,可以相互作用,具有较高活性;在Sirt2(NAD+)-INA体系中,INA与催化底物NAD+距离较远,与在Sirt1体系中比较,INA对Sirt2体系的活性较弱,结果与实验一致.本文的研究,对今后以去乙酰化酶Sirt1,Sirt2为靶点的新药开发具有一定指导意义.     

烟酰胺辅酶结构及反应机理若干物理有机化学问题

烟酰胺腺嘌呤二核苷三磷酸(烟酰胺辅酶NAD(P)H)是生命体内最重要的一种氧化还原酶(即氢转移酶)的辅酶,在生命体内直接担负着转移或传递负氢离子和电子给底物分子的职能.因此,烟酰胺辅酶一直是生物学家们和化学家们十分关注的一个明星分子.     

光催化NAD（P）H再生的研究进展

辅酶与酶催化反应紧密相关,是酶催化氧化还原反应过程中不可缺失的重要组成,其中,烟酰胺类辅酶NAD和NADP参与了大多数的酶催化氧化还原反应,是辅酶中最重要的一类。然而,辅酶的高成本限制了其实际应用。因此,烟酰胺辅酶的高效和低成本再生具有特别重要的意义。本文总结了还原型烟酰胺辅酶光催化再生方法的相关研究进展以及各种光敏剂的优缺点,提出了光催化NAD(P)H再生仍需要解决的问题。     

脱氢酶电化学生物传感器的研究进展

自然界中超过400种脱氢酶使用辅酶-烟酰胺腺嘌呤二核苷酸(NAD+)或烟酰胺腺嘌呤二核苷酸磷酸(NADP+)作为生物催化反应中氢和电子的传递体,因此烟酰胺型辅酶的电化学氧化对构筑此类脱氢酶电化学生物传感器具有重要的意义.本文介绍了还原型辅酶在人工电子媒介体存在下的电化学氧化,以及脱氢酶电化学生物传感器的设计和应用.     

Synthesis of NAD analogs to develop bioorthogonal redox system

Three new nicotinamide adenine dinucleotide(NAD) analogs were synthesized,and their characteristics as cofactors for Escherichia coli malic enzyme(ME) and its double mutant ME L310R/Q401C were analyzed.Each pair of the NAD analog and the double mutant showed good orthogonality to the natural pair of NAD and ME in terms of catalyzing oxidative decarboxylation of L-malic acid.Results indicated that molecular interactions between redox enzyme and cofactor could be further explored to generate new bioorthogonal redox systems.     

PHOTOCHEMICAL LABELING OF YEAST ALCOHOL DEHYDROGENASE WITH AN AZIDE ANALOG OF NAD +

Abstract— 3-Azidopyridine adenine dinucleotide, an azide analog of NAD⁺, has been synthesized as a potentially general photochemical labeling reagent for the active sites of NAD-dependent dehydrogenases. The analog is a competitive inhibitor of NAD reduction by yeast alcohol dehydrogenase (YADH). Upon photolysis of the ³H-analog in the presence of YADH, 7% of the label becomes covalently bound. The results are discussed in terms of desired properties of a photochemical labeling reagent.     

Synthesis of 1,2,3-triazole moiety-containing NAD analogs and their potential as redox cofactors

Thirteen 1,2,3-triazole moiety-containing NAD analogs were synthesized and evaluated as redox cofactors. Noticeable enzymatic activities were observed when these analogs were employed as cofactors for malic enzyme or alcohol dehydrogenase. Our results indicated that the natural NAD-dependent oxidoreductases possessed flexible NAD binding pockets.     

Coenzyme analogs: excellent substitutes (not poor imitations) for electrochemical regeneration

For the first time, employment of nicotinamide coenzyme NAD analogs has overcome the limitations of NAD in electrochemical regeneration. It has been shown that NAD analogs, APAD and PAAD, were electrochemically reduced more efficiently than original NAD and that the stability of their reduced products was also much higher than NADH.     

Two-dimensional infrared spectroscopy of azido-nicotinamide adenine dinucleotide in water

Mid-IR active analogs of enzyme cofactors have the potential to be important spectroscopic reporters of enzyme active site dynamics. Azido-nicotinamide adenine dinucleotide (NAD(+)), which has been recently synthesized in our laboratory, is a mid-IR active analog of NAD(+), a ubiquitous redox cofactor in biology. In this study, we measure the frequency-frequency time correlation function for the antisymmetric stretching vibration of the azido group of azido-NAD(+) in water. Our results are consistent with previous studies of pseudohalides in water. We conclude that azido-NAD(+) is sensitive to local environmental fluctuations, which, in water, are dominated by hydrogen-bond dynamics of the water molecules around the probe. Our results demonstrate the potential of azido-NAD(+) as a vibrational probe and illustrate the potential of substituted NAD(+)-analogs as reporters of local structural dynamics that could be used for studies of protein dynamics in NAD-dependent enzymes.     

Evaluation of complexes of DNA duplexes and novel benzoxazoles or benzimidazoles by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry is used to compare the metal ion binding and metal-mediated DNA binding of benzoxazole (1, 2, 3, 4) and benzimidazole (5) compounds and to elucidate the putative binding modes and stoichiometries. The observed metal versus non-metal-mediated DNA binding, as well as the specificity of DNA binding, is correlated with the biological activities of the analogs. The ESI-MS spectra for the antibacterial benzoxazole and benzimidazole analogs 4 and 5 demonstrated non-specific and non-metal-mediated binding to DNA, with the appearance of DNA complexes containing multiple ligands. The anticancer analog 2 demonstrates a clear preference for metal-mediated DNA interactions, with an apparent selectivity for Ni2+ -mediated binding over the more physiologically relevant Mg2+ or Zn2+ cations. Complexation between DNA and the biologically inactive analog 1 was not observed, either in the absence or presence of metal cations.     

Synthesis of phosphodiester-type nicotinamide adenine dinucleotide analogs

Fourteen phosphodiester-type β-nicotinamide adenine dinucleotide (NAD⁺) analogs were prepared starting from nicotinamide. The phosphodiester linkage was effectively assembled in 69-93% yields via condensation reaction between 2′,3′-di-O-acetyl nicotinamide mononucleotide and alcohols in the presence of 2,4,6-triisopropylbenzenesulfonyl chloride. The analog β-nicotinamide ribose-5-(2-phenylethyl) phosphate showed beneficial effects on cell growth of model microorganisms.     

Synthesis of amino core compounds of galactosyl phytosyl ceramide analogs for developing iNKT-cell inducers

1-Aminophytosphingosine and 6-aminogalactosyl phytosphingosine were prepared in 61% and 40% yield libraries with 44 carboxylic acids showed that a 4-butylbenzoic acid-derived product exe, respectively. Glycosylation using benzoyl-protected lipid resulted in better a-selectivity for ceramide analogs, but the yield was less than that obtained with benzyl moieties. Screening the amide rted less cytotoxicity. These analogs were purified for validation of immunological potencies and the a-GalCer analog but not the sphingosine analog stimulated human iNKT cell population.     

Solution conformation by NMR and molecular modeling of three sulfide-free somatostatin octapeptide analogs compared to angiopeptin

Summary The conformation in dimethylsulfoxide of the somatostatin derivative angiopeptin and of three disulfide-free analogs was estimated by two-dimensional nuclear magnetic resonance spectroscopy at room temperature. The resulting 3D molecular graphics were compared and shown to reflect the observed differences in the inhibition of restenosis after rat aorta balloon injury by these octapeptide inhibitors. Angiopeptin and its active analog 2 displayed a relatively rigid conformation of the cyclic hexapeptide backbone due to the presence of two well-defined hydrogen bonds, further stabilized by a third hydrogen bond outside the ring. No such constraints were detected for the two biologically inactive analogs, which, compared to 2, had a two-atom longer or shorter hexapeptide ring. The well-defined structure of compound 2 may serve as an improved pharmacophore for this new class of drugs.     

Carbocyclic analogs of anhydrothymidines

The carbocyclic analog of thymidine (C-Thymidine, 2 ) was converted to the analog of 3′-(O-methanesulfonyl)-5′-O-tritylthymidine, which was cyclized in alkaline solution or with 1,5-diazabicyclo[5.4.0]undec-5-ene (DBU) to the carbocyclic analog of 5′-O-trityl-2,3′-anhydrothymidine ( 6 ). Hydrolysis of the latter compound produced the carbocyclic analog of all-cis-thymidine. C-Thymidine was also converted to the carbocyclic analog of 3′-O-acetyl-2,5′-anhydrothymidine ( 12 ) by treating the 5′-O-methanesulfonyl analog with DBU. Hydrolysis of the anhydro derivative gave back C-Thymidine. The carbocyclic analog ( 3 ) of 3′-deoxy-2′-hydroxythymidine was converted similarly to the corresponding 2,2′-anhydrothymidine ( 15 ) and 2,5′-anhydrothymidine ( 21 ) analogs. As expected, C-5′-O-trityl-2,2′-anhydrothymidine formed more readily than did the 2,3′-anhydrothymidine analog. Hydrolysis of these 2,2′- and 2,5′-anhydrothymidine analogs gave, respectively, the carbocyclic analog of all-cis-3′-deoxy-2′-hydroxythymidine and 3 .