反胶束体系中脂肪酶催化合成异丁酸异戊酯

报道了在CTAB/正己烷和AOT/正己烷反胶束体系中,CCL脂肪酶催化合成异丁酸异戊酯的新方法.考察了水含量w₀、底物与酶的比例、缓冲溶液pH值以及温度等因素对脂肪酶催化酯合成反应的影响.研究结果表明,两种反胶束体系均为合成异丁酸异戊酯提供了较为合适的微环境,所选定的脂肪酶在CTAB和AOT反胶束中的活性分别是有机溶剂中反应活性的6倍和4倍.     

直链醇对反胶束体系中木素过氧化物酶催化活性的影响

根据研究发现, 在有醇作助表面活性剂的CTAB反胶束中木素过氧化物酶(LiP)不能表现活力, 而在水介质中CTAB对LiP的催化活性影响又不是很大. 为了揭示其中醇的影响, 本工作就不同碳链长度的醇对LiP酶催化性能的影响进行了研究. 由于CTAB反胶束体系中醇浓度较高, 且碳原子数大于4的直链醇在水中的溶解度又很小, 为此采用了LiP可在其中显示催化活性的CTAB正胶束、AOT反胶束和Brij30反胶束作介质, 通过研究这些介质中不同链长的醇对LiP催化活力的影响, 来探讨CTAB反胶束中木素过氧化物酶(LiP)不能表现活力的原因. 结果表明, 不管表面活性剂聚集体的结构、电性质及反胶束大小如何, 只要醇的浓度超过500 mmol•L^－1 (丁醇≥1200 mmol•L^－1), LiP在上述原本可显示活力的介质中均无催化活性. 据此推测CTAB反胶束中木素过氧化物酶(LiP)不能表现活力的原因主要是由助表面活性剂醇造成的.     

反相胶束中脂肪酶催化猪油的甘油解反应

单脂肪酸甘油酯;反相胶束中脂肪酶催化猪油的甘油解反应     

AEOT/异辛烷/水反胶束体系中合成导电聚苯胺

利用阴离子表面活性剂丁二酸二[2-(2-乙基己氧基)乙基]酯磺酸钠(AEOT)形成的反胶束为模板,制备出粒径小而均匀的导电聚苯胺.讨论了反应时间、反应温度、氧化剂与单体的摩尔比、酸浓度、表面活性剂用量及表面活性剂循环利用对聚合产物性能的影响.利用紫外-可见光谱、红外光谱、X射线衍射、Olympus显微镜及透射电镜对产物进行了表征.     

盐酸胍对反胶束中RNase A活性的影响

以胞嘧啶核苷酸2',3'-环单磷酸酯为底物研究了变性剂盐酸胍对十二胺丁酸盐-环己烷反胶束溶液中核糖核酸酶A活性的影响,同水溶液相比,盐酸胍对反胶束中酶活性的抑制作用很小。反胶束的大小限制了酶分子天然态构象的改变,从而保证了其活性中心的完整性。核糖核酸酶A的内源荧光研究发现,同水溶液相比,反胶束中蛋白的最大发射波长没有发生变化,但荧光偏振极化度增加,也表明了在反胶束中酶分子的运动自由度较在水溶液中有所降低。     

AOT/Triton X-100混合反胶束体系中假丝酵母脂肪酶催化蓖麻油水解的活性

研究了二(2-乙基己基)琥珀酸磺酸钠(AOT)/Triton X-100混合反胶束体系中假丝酵母脂肪酶(candida rugosa lipase)催化蓖麻油水解的反应. 考察了Triton X-100占总表面活性剂的摩尔分数(x(Triton X-100))、水与总体表面活性剂的摩尔比(ω0)、pH值、反应温度以及底物蓖麻油的浓度等因素对酶活性的影响. 研究结果表明, 加入非离子表面活性剂Triton X-100可以使假丝酵母脂肪酶的活性得到显著提高, 但是当底物蓖麻油的浓度大于0.24 mol·L-1时, 会对假丝酵母脂肪酶产生抑制作用.     

混合反胶束的电导与微结构研究

反胶束是两亲分子在非极性溶剂中形成的一种有序组合体，在医药、化工、采油、胶束催化及酶催化等领域中有重要应用．与胶束溶液相比，人们对反胶束的形成与结构的了解至今仍不充分．特别是对于由混合表面活性剂形成的反胶束的研究几乎无人涉及．本文采用动态光散射、电导及荧光光谱等手段对阴离子表面活性剂AOT与非离子表面活性剂形成的混合反胶束进行了研究，旨在探讨利用表面活性剂的复配来调节和控制反胶束的结构和性能．亚实验部分二异辛基磺化琉璃酸钠（AOT，Sigma公司）；Brij30为含4个氧乙烯基（EO基）的十二碳醇（AcrosOrgani…     

反胶束中的酶催化研究进展

评述酶在反胶束中的定位和结构、动力学特性、催化活性和稳定性，反胶束作为酶催化反应介质的优点，反胶束中酶催化反应的类型及其应用。     

金属胶束催化体系中经Turing分支形成的空间有序结构与催化活性

摘要基于金属胶束催化反应的三元复合物动力学模型, 分析了金属胶束作为一类特殊的超分子体系, 其参与催化反应的特殊动力学行为与体系中可能出现的自组织结构的关系. 研究结果表明, 在一定的边界条件下, 即使基元反应是线性化学反应步骤, 由于扩散步骤与化学反应的耦合, 以及非理想性的组分热力学行为, 也将不可避免地出现经Turing分支形成的浓度场空间自组织. 计算结果表明, 这种宏观有序结构的形成将使金属胶束催化体系中呈现出以存在反应活性极高的位点为特征的反应活性的空间有序分布; 从自组织理论的角度对这类胶束体系催化活性的时空有序特征给予一定程度的阐释.     

Influence of Gold Nanoparticles of Varying Size in Improving the Lipase Activity within Cationic Reverse Micelles

Herein, we report the effect of gold nanoparticles (GNPs) in enhancing lipase activity in reverse micelles of cetyltrimethylammonium bromide (CTAB)/water/isooctane/n‐hexanol. The size and concentration of the nanoparticles were varied and their specific roles were assessed in detail. An overall enhancement of activity was observed in the GNP‐doped CTAB reverse micelles. The improvement in activity becomes more prominent with increasing concentration and size of the GNPs (0–52 μM and ca. 3–30 nm, respectively). The observed highest lipase activity (k₂=1070±12 cm³ g^?1 s^?1) in GNP‐doped CTAB reverse micelles ([GNP]: 52 μm, ca. 20 nm) is 2.5‐fold higher than in CTAB reverse micelles without GNPs. Improvement in the lipase activity is only specific to the GNP‐doped reverse micellar media, whereas GNP deactivates and structurally deforms the enzyme in aqueous media. The reason for this activation is probably due to the formation of larger‐sized reverse micelles in which the GNP acts as a polar core and the surfactants aggregate around the nanoparticle (‘GNP pool’) instead of only water. Lipase at the augmented interface of the GNP‐doped reverse micelle showed improved activity because of enhancement in both the substrate and enzyme concentrations and increased flexibility in the lipase conformation. The extent of the activation is greater in the case of the larger‐sized GNPs. A correlation has been established between the activity of lipase and its secondary structure by using circular dichroism and FTIR spectroscopic analysis. The generalized influence of GNP is verified in the reverse micelles of another surfactant, namely, cetyltripropylammonium bromide (CTPAB). TEM, dynamic light scattering (DLS), and UV/Vis spectroscopic analysis were utilized to characterize the GNPs and the organized aggregates. For the first time, CTAB‐based reverse micelles have been found to be an excellent host for lipase simply by doping with appropriately sized GNPs.     

新型阴离子表面活性剂的合成及其反胶束体系的酶催化性能

合成了未见文献报道的新型阴离子表面活性剂磷酸二[(2-乙基己氧基)乙基]酯钠(sodium di-[(2-ethylhexyloxy)ethyl] phosphate,DEEPA);以核磁共振氢谱和红外光谱表征了它的结构;在DEEPK/异辛烷反胶束体系中进行了脂肪酶催化橄榄油水解反应实验.结果表明,该反胶束体系的催化活性优于AOT反胶束体系,更优于油-水双相中的酶催化反应,最大活性是油-水双相体系的1.86倍.     

Catalytic Activity of Hexokinase in Reversed Micelles

Reversed micelles can control the size of water pools and the physical property of water by changing W(0)(=[water]/[surfactant]). Hexokinase (HK) activity seems to be easily affected by the microenvironment in the neighborhood of the enzyme because it is assumed that HK binds to the outer mitochondrial membrane by insertion of its hydrophobic NH(2) tail. The catalytic activity of HK was examined in reversed micelles in order to study the effect of the microenvironment in the neighborhood of HK on the activity. Sodium bis(2-ethylhexyl)sulfosuccinate (AOT), hexadecyltrimethyl ammonium chloride (HTAC), and octaoxyethylene dodecyl ether (C(12)E(8)) were used as anionic, cationic, and nonionic surfactants, respectively. HK activity was obtained by measuring ATP and ADP amounts with HPLC. The high electrostatic inner surfaces of AOT and HTAC reversed micelles were not favorable for HK to exhibit the catalytic activity, but the activity in HTAC reversed micelles was 2-3 times higher than that in AOT reversed micelles and the activities in both reversed micelles revealed an optimum at W(0)=10. The phenomenon was discussed in connection with the location of HK, nonuniform distribution of substrates, and the size and physical properties of the water pools. On the other hand, HK activity was much higher in C(12)E(8) reversed micelles than in AOT and HTAC reversed micelles and increased with the concentration of C(12)E(8). This suggests that HK activity is easily revealed in hydrated ethylene oxide chains. In conclusion, it was demonstrated that HK activity depends on the microenvironment such as the electrostatic field, the physical properties of water, and the hydrophobicity. Copyright 2001 Academic Press.     

醇脱氢酶在反胶束溶液中的催化动力学性质

以十六烷基三甲基溴化铵(CATB)-辛烷-己醇反胶束体系对醇脱氢酶(ADH)进行固定化,试验了含水量、酶液pH值、CTAB和己醇浓度对ADH固定化的影响。对游离酶和固定化酶的催化动力学性质研究表明：酶促反应的最适pH值分别为8.2和8.8,最适温度分别是31℃和20℃,对乙醇的米氏常数Km分别为12mmol/L和7.4mmol/L。在30℃时,游离酶存放150min后失活90%,固定化酶失活50%,表明反胶束固定化ADH有较好的热稳定性。     

Gas Hydrate Formation in Reversed Micelles

We describe a technique to modify protein solubility and optimize enzyme activity in reversed micellar solutions. The technique is based on the ability of hydrates of natural gas to form in the micro-aqueous phase. Clathrate hydrates are crystalline inclusions of water and gas, and their formation in bulk water has traditionally been studied with relevance to natural gas recovery. We have found that hydrates can form in the environment of the microaqueous pools of reversed micelles, and that their extent of formation can be well controlled through the thermodynamic variables of temperature and pressure. Additionally, formation of hydrates affects the size and aggregation number of the micelles, and thus influences the solubility and conformation of encapsulated proteins. We demonstrate how the concept can be used in two applications: (i) protein extraction into reversed micelles and subsequent recovery, and (ii) optimization of enzyme activity in reversed micelles.     

无机杂化脂肪酶的制备及其催化性能研究

采用脂肪酶为有机组分,Ca2+、Zn2+、Mn2+和Cu2+等4种金属磷酸盐为无机组分,制备脂肪酶-无机杂化纳米花,系统研究4种杂化脂肪酶的结构和催化活性。结果表明,制备的杂化脂肪酶具有花状的层级片状结构,并探究了无机杂化脂肪酶的最优反应时间为10 min,反应温度为40 ℃,pH为8。4种金属离子制备的杂化脂肪酶包封率达到90%以上。相比于游离脂肪酶,杂化脂肪酶的催化水解活性、催化反应速率、耐温性、耐变性剂均有所提高,其中Ca2+金属磷酸盐合成的杂化脂肪酶催化效率是游离脂肪酶的1.87倍,合成的杂化脂肪酶表现出良好的重复使用性。     

聚苯胺纳米粒子的反胶束法合成及自组装

聚苯胺纳米粒子的反胶束法合成及自组装;聚苯胺;纳米粒子;反胶束;自组装     

磷脂对脂肪酶催化性能的影响

脂肪酶催化可再生动植物油脂的酰基化反应可以生产多种具有重要价值的化工产品,近年来受到了越来越多的关注.而天然油脂原料中往往含有一定量的磷脂,它对脂肪酶的催化活性、热稳定性以及反应动力学等的影响非常显著.介绍了油脂中存在磷脂的种类与结构,并分别针对脂肪酶催化的水解、酯化和转酯化反应过程,综述了磷脂对脂肪酶催化性能的影响,以及可能的作用机制.     

分光光度法测定微乳液中脂肪酶的酶活

通过对胶束酶学对传统脂肪酶酶活测定的改进,建立了适合于油包水微乳液体系中脂肪酶酶活测定的分光光度方法。与传统方法相比,本法克服了底物乳化液难配制、不稳定等缺点,无需进行在pH缓冲溶液体系中的酸碱滴定,提高了酶活测定的准确性。