含磷丙酮酸脱氢酶系抑制剂的研究进展

丙酮酸脱氢酶系是生物体内重要的氧化还原酶之一,其催化丙酮酸氧化脱羧转化为乙酰辅酶A是生物体内的关键代谢过程,在生物化学研究中具有重要的意义.根据生物化学的理由来进行新药分子生物合理设计的观点,丙酮酸脱氢酶系是一个具有重要意义和值得探索的靶标.研究表明许多有机磷化合物是一类重要的丙酮酸脱氢酶系抑制剂.本文系统介绍了含磷丙酮酸脱氢酶系抑制剂的研究历程和研究动态,并结合本课题组的研究工作对代表性的研究结果和进展进行了总结和评述.     

L-乳酸脱氢酶催化反应机理的理论研究进展

介绍Ｌ－乳酸脱氢酶可逆催化氧化Ｌ－乳酸生成丙酮酸的反应机理研究的最新进展。讨论底物及活性中心附近残基的构型对反应的影响以及Ｈ－离子转移的可能机理。     

具有除草活性的α-氧代膦酸衍生物研究进展

简要的总结了十三个系列的α-氧代膦酸衍生物的合成和生物活性的研究进展。为了获得具有较高除草活性及商品化潜力的新型膦酸脂,尝试采用生物合理设计的方法设计新型的丙酮酸脱氢酶系抑制剂,通过在合成、生物测定、机理及生物化学研究的基础上进行构效关系及结构优化的研究,发现α-(取代苯氧乙酰氧基)烃基膦酸酯为一类兼具有良好除草活性和植调活性的先导母体,研究证明该类化合物为丙酮酸脱氢酶系的强抑制剂。     

介体型乳酸脱氢酶生物传感器的研制及应用

本报道了能对丙酮酸产生良好响应的电流型乳酸脱氢酶生物传感器。该传感器以耐尔兰Ａ修饰浸石墨电极为基体电极，将酶直接固化在蚕丝蛋白膜上。在ＰＨ７．４的ＮａＨ２ＰＯ４－ＮａＯＨ介质中，当２．４×１０＾－４ｍｏｌ／Ｌ的辅酶Ｉ（ＮＡＤＨ）存在下，该传感器的响应电流与丙酮酸浓度在３．２×１０＾－５ｍｏｌ／Ｌ范围内有良好的线性关系。响应时间为６０ｓ．本讨论了影响传感器响应的各种因素，用此传感器测定了人血清中     

基于丙酮酸/还原型辅酶I/乳酸脱氢酶/氧化型辅酶I/乳酸正逆反应同时测定丙酮酸/乳酸的酶荧光毛细管分析

利用丙酮酸(PA)/还原型辅酶I(NADH)/乳酸脱氢酶(LDH)/氧化型辅酶I(NAD+)/乳酸(LA)荧光反应体系的正逆反应,建立了一种可直接用于临床检验、能同时测定血清中微量PA/LA的酶荧光毛细管分析法.本方法可在常规荧光光度计上,用普通玻璃毛细管同时实现了PA/LA的高灵敏分析,每次分析试剂和样品的用量仅9 ...     

离子排斥法测定丙酮酸发酵提取液中的丙酮酸含量

建立一种测定丙酮酸发酵液中丙酮酸含量的方法。采用有机酸离子排斥柱,TSKgel OApak-A为分析柱,TSKgel OApak-P为保护柱;柱温:40℃;流动相:4.5mmol/L H2SO4,流速0.8mL/min;检测波长:210nm。丙酮酸在42.45~2122.3mg/L范围内,峰面积与样品浓度有良好的线性关系(A=4.7278c 31.6296,r=0.9999),检出限为4.6mg/L。发酵液中丙酮酸含量在5.1%左右,丙酮酸的回收率为97.11%~99.21%。     

二价金属离子影响乳酸脱氢酶活性的单扫伏安研究

探讨了５种二价金属离子对乳酸脱氢酶在辅酶ＮＡＤＨ存在下转化丙酮酸为乳酸催化体系的影响、结果表明，Ｚｎ＾２＋，Ｃａ＾２＋与ＬＤＨ活性无影响，Ｍｎ＾２＋有抑制作用，而Ｃｕ＾２＋，Ｍｇ＾２＋在低浓度时有微弱的促进作用。     

微量乳酸脱氢酶毛细管电泳在线反应电化学检测方法的研究

以乳酸脱氢酶催化乳酸与NAD^ 反应生成丙酮酸与NADH和安培法检测NADH为基础,利用电泳中介微分析（EMMA）技术,研究了超微量乳酸脱氢酶的毛细管电泳在线反庆的电化学检测方法,并从理论上对EMMA电泳图中的平台宽度和高度作了初步探讨,结果表明,在EMMA的恒高压和零高压两种模式下,使用直径为150μm和束状碳纤维电极,在＋0.8V检测电位下,对LDH活性检测灵敏度分别为1.1nU和0.6nU;所导出的平台高度、宽度与实验条件的关系式对提高毛细管电泳分离效率和检测灵敏度有一定指导意义。     

紫外分光光度法测定丙酮酸

基于丙酮酸在紫外吸收光谱290～340nm区有较强的吸收,建立了分光光度法测定丙酮酸(盐)的方法。在pH11．0的水溶液中,位于320nm处,丙酮酸有吸收,而其他有机酸和杂质无吸收或吸收不明显。在320nm处,丙酮酸在0．2～2．8g／L范围内符合比耳定律,其R2为0．9997,平均回收率99．8％,RSD0．46％。该法适合于发酵液和分离提取过程中丙酮酸及其盐类的测定。     

酶荧光毛细管分析法测定微量血清中乳酸脱氢酶活性

基于丙酮酸/还原型辅酶I/乳酸脱氢酶(LDH)/乳酸/氧化型辅酶I荧光猝灭体系和荧光毛细管分析技术,建立了可用于微量样品中LDH酶活性测定的方法。优化的测定条件为:激发及发射波长分别为350和460nm;测定温度为25℃;酸度为pH 6.5;NADH浓度为300μmol/L;丙酮酸浓度为1.2mmol/L。本方法的测定范围为50～1500IU/L,检出限为30IU/L,相对标准偏差2.1%～2.2%(n=10),回收率在96.4%～105%范围内。本方法操作简单,每次测定仅需样品2.0μL、试剂18.0μL,分析速度约为30样/h,利用本方法测定了微量血清中LDH的活性。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.