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1.
甲烷单加氧酶的催化性能   总被引:3,自引:0,他引:3  
研究了来源于ethylomonas sp.GYJ3菌的甲烷单加氧酶(MMO)的催化性能,结果表明,当组成该酶的三个组分,羟基化酶、调节蛋白B和还的酶的摩尔比为1:1.7:2.0时,重组的MMO体系酸疼的比活最高,为342nmol/(mg.min),当反应体系的PH在6.5-7.5时,MMO酶的活力最大,研究了纯MMO催化甲烷羟基化反应作丙烯环氧化反应的特性,以及金属离子和电子本对MMO催化反应的影  相似文献   

2.
有机溶剂中(R)-醇腈酶催化不对称合成(R)-苯乙醇腈   总被引:3,自引:0,他引:3  
 研究了来源于杏仁的(R)-醇腈酶在有机溶剂异丙醚中催化苯甲醛与HCN不对称合成(R)-苯乙醇腈,初步探讨了来源于不同杏仁的(R)-醇腈酶的筛选、最适酶量的确定以及底物HCN与苯甲醛的配比、底物浓度、酶的微环境pH和反应温度对不对称合成反应的影响.结果发现,来源于苦杏仁的(R)-醇腈酶优于来源于甜杏仁的(R)-醇腈酶.优化的反应条件为:最适酶量150g/L,HCN与苯甲醛的配比2.5,苯甲醛浓度300mmol/L,酶的微环境pH5.4,反应温度0~5℃.在该优化反应条件下,反应平衡转化率和产物的光学纯度均高达99%以上.  相似文献   

3.
用电子顺磁共振(EPR)法,化学发光法及荧光光谱法研究了100例正常人、42例角膜移值患者泪液中的自由基、超氧化物岐化酶(SOD)和水溶性脂质过氧化物(WSLP)等指标.结果表明正常人泪液中自由基的自旋浓度是(3.6±0.58)×1012spins/mL,SOD浓度为(3.84±1.45)μg/L、水溶性脂质过氧化物相对荧光强度为9.598~16.225U/mL.角膜移植后三项指标变化出现两个规律的峰,这种规律性变化在三项指标间存在显著的相关性.其中5例患者的特殊变化证明移植排斥反应与术后这些变化的进一步持续发展有关  相似文献   

4.
对几种有机溶剂中猪胰脂肪酸催化的酯交换反应进行了研究,详细考察了反应温度、反应时间、反应物摩尔比、反应物中水含量和不同溶剂对反应性能的影响。结果表明:1.反应温度在313K左右时酶显示出最高催化活性。2.在实验条件下,反应进行72h后,转化率不再随反应时间的延长而变化,即反应达到平衡。3.酯/醇摩尔比的增大对反应转化率的影响较小。4.反应系统中水含量为0.5%-1.3%时,酶的催化活性最高。5.酶的催化活性随溶剂极性增大而降低。  相似文献   

5.
研究了无水硫化钠与对二氯苯(以N-甲基吡咯烷酮为溶剂)合成聚苯硫醚反应的宏观动力学,该反应是一个小分子缩合串联自缩聚的过程,通过测定不同反应聚合体系中氯化钠的徨成率和硫化内的转化率,建立了该反应的宏观动力学方程:1/(1-PNaCl+PNa2s)=C0Kt+1;并计算得到220、250℃的表观反应速率为4.5×10^-4和3.0×10^-3kg/(mol.s),表观活化能为134kJ/mol。  相似文献   

6.
无溶剂体系中的脂肪酶催化反应研究进展   总被引:1,自引:3,他引:1  
酶作为一种生物催化剂,具有专一性强、催化效率高、在常温常压等温和条件下能进行操作等优点,从而引起众多学者的兴趣.传统酶学研究的是酶在水溶液中的催化行为,这使得人们产生了误解,认为只有在水溶液中酶才能保持活性,有机溶剂会使酶变性失活.1984年,美国麻省理工工学院的科学家Klibanov首次发现有许多酶可用于有机溶剂,从而解决了有机化合物在水介质中的低溶解性限制酶催化剂应用的问题,酶不仅能够在有机溶剂中保持稳定,而且还显示出很高的催化转酯活力.这一发现为酶学研究和应用带来了又一次革命性飞跃,从而促进了非水酶学的兴起,使之成为目前重要的酶技术之一.其中研究较多的是脂肪酶,脂肪酶不仅能催化油脂水解,而且在非水介质中也能催化油脂的酯交换反应,用来提高油脂的品位.随着研究的深入和学科的交叉,各种新的酶促反应体系也相继被发现,大大拓宽了酶催化反应的应用范围,使酶法合成逐步发展成为与化学法合成相互补充的合成方法.近年来非水介质中的不同反应体系的酶催化反应,主要有:有机溶剂体系、反相胶束体系、超临界体系、气相体系等,其中无溶剂体系中的酶促反应是非水体系中酶促反应的特例.  相似文献   

7.
在0.1mol/L的磷酸盐缓冲溶液(pH7.4)中,用微量热法测定了298.15K时漆树漆酶与邻氨基苯酚反应的摩尔反应焓ΔrHm=252.21±3.59kJ/mol,米氏常数Km=7.77×10-3mol/L和表观一级反应速率常数k1=7.23×10-3s-1,及此条件下邻氨基苯酚作底物时的漆酶活性值EA=0.190(IU)。  相似文献   

8.
氧化藏红T褪色催化荧光法测定痕量钒   总被引:13,自引:3,他引:13  
陈兰化  罗兵 《分析化学》1997,25(6):656-658
研究了在酸性介质中柠檬酸存在下,痕量钒(V)催化溴酸钾氧化藏红T的褪色反应及其动力学条件,建立了催化荧光测定痕量钒的新方法。催化反应在沸水浴中进行8min,为假零级反应,反应的表观活化能力为99.21kJ/mol,反应速度常数为0.12/s;该方法的检出限为2.2×10^-8g/L;线性范围为0.2 ̄2.4μg/L研究了共存离子的影响,用于人发和煤灰中痕量钒的测定,结果令人满意。  相似文献   

9.
陈瑞川  万桢 《应用化学》1998,15(6):25-28
以电化学聚合法在石墨电极上获得聚间苯二胺膜(PMPD),并建立了快速、灵敏的膜质量检验方法:辣根过氧化物酶(HRP)标记PMPD膜-邻苯二胺(OPD)反应法,对聚合、活化等条件作了研究;进一步制成了检测乙肝表面抗原(HBsAg)和检测鼠免疫蛋白(MIgG)的免疫电极,对血清样品作了检测.结果表明:2.5V电池电压下,于含0.12mol/LMPD的1.2mol/LH2SO4中聚合20min,再以30g/L浓度的戊二醛活化4h,所得HRP标记电极及免疫电极重现性好;检测HB-sAg和MIgG的线性范围分别为0.1~3.2mg/L及0.1~10mg/L  相似文献   

10.
研究了核糖核酸酶A(RNaseA)在丁酸十二铵(DAB)-环己烷反胶束溶液中催化水解胞苷2',3'环单磷酸酯的动力学,数据符合Michaelis-Menten酶催化机理。以kcat/Km表示酶催化活性时,RNaseA在反胶束溶液中的催化活性是在水溶液中的14 ̄30倍。无论是固定DAB浓度还是固定H2O与DAB浓度之比,随增溶水量的增加,kcat/Km呈下降趋势。  相似文献   

11.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

12.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

13.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).  相似文献   

14.
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.  相似文献   

15.
In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.  相似文献   

16.
Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.  相似文献   

17.
用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.  相似文献   

18.
19.
A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu0 as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than CuI in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).  相似文献   

20.
(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C60, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.  相似文献   

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