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研究了微波辐射和常规加热下脂肪酶Novozyme 435催化甘油与n-辛酸的反应。在2种加热模式下,n-辛酸与甘油反应的初速度随着反应温度(50~75℃)的升高而加快;同样条件下,微波辐射下的反应初速度略高于常规加热条件下的。微波辐射的产物中的2-单甘酯和1,2-二甘酯的含量增加,但仍明显低于1-单甘酯和1,3-二甘酯的含量,即微波辐射并未根本改变脂肪酶的1,3-专一性;但实验条件下微波辐射均削弱了Novozyme 435的1,3-专一性:微波辐射反应产物中1-单甘酯与2-单甘酯的量比由常规加热下的26.9~43.4下降为16.2~40.4,其中1,3-二甘酯与1,2-二甘酯的量比亦由10.5~19.6降为7.6~15.3。 相似文献
3.
常见金属离子对漆酶酶活的影响 总被引:14,自引:0,他引:14
检测了14种不同的金属离子对两种漆酶(laccaseA和laccaseB,简称LacA和LacB)活性的影响.结果表明:Al3+,Fe3+,Ag+,Hg2+对两种漆酶的活性都有抑制作用,其中Fe3+,Ag+的抑制作用最强,酶活完全损失;Mg2+,Cu2+对两种漆酶的活性有激活作用. 相似文献
4.
水相胶束体系中底物微环境对辣根过氧化物酶催化反应的影响 总被引:1,自引:0,他引:1
利用荧光测活法比较了HRP在有机相与水相胶束体系中催化不同芳香胺类的动力学常数,发现在水相胶束体系中,HRP是在一个较严格的亲、疏水界面进行催化反应。同时对界面酶学性质进行了初步研究,讨论了在胶束中不同增溶位置对反应动力学常数的影响。 相似文献
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研究了在有机溶剂中固定化Alcaligenes sp.脂肪酶催化α-氰基-3-苯氧基苄醇乙酯的对映体选择性转酯化反应,考察了不同性质的溶剂和酰基受体对酶的催化活性和选择性以及对产物稳定性的影响.结果发现在弱极性溶剂如正己烷中酶具有较高的催化活性但产物e.e.%值低,而且容易分解;在四氢呋喃等溶剂中酶催化活性相对低,但产物e.e.%值高,也较为稳定;但反应时间太长,会导致产物分解及纯度下降;不同酰基受体对酶反应无显著影响,甲醇为最佳酰基受体,太多醇会导致反应速率下降;溶剂水含量大于2.0%时对酶活性和产物稳定性产生明显不利影响.在优化条件下,酶反应可得到(S)-α-氰基-3-苯氧基苄醇产率>48%,纯度>99%e.e. 相似文献
7.
研究了在有机溶剂中固定化Alcaligenes sp.脂肪酶催化α-氰基-3-苯氧基苄醇乙酯的对映体选择性转酯化反应,考察了不同性质的溶剂和酰基受体对酶的催化活性和选择性以及对产物稳定性的影响.结果发现在弱极性溶剂如正己烷中酶具有较高的催化活性但产物e.e.%值低,而且容易分解;在四氢呋喃等溶剂中酶催化活性相对低,但产物e.e.%值高,也较为稳定;但反应时间太长,会导致产物分解及纯度下降;不同酰基受体对酶反应无显著影响,甲醇为最佳酰基受体,太多醇会导致反应速率下降;溶剂水含量大于2.0%时对酶活性和产物稳定性产生明显不利影响.在优化条件下,酶反应可得到(S)-α-氰基-3-苯氧基苄醇产率>48%,纯度>99%e.e. 相似文献
8.
无机盐水合物对有机溶剂中酶促寡肽合成的影响 总被引:4,自引:0,他引:4
必需水的存在是酶在有机溶剂中保持活性的关键。本文研究了自由水初始水含量对有机溶剂中α-胰凝乳蛋白酶(α-chymotrypsin)和嗜热杆菌蛋白酶粗品(thermoase)催化合成寡肽的影响。用无机盐水合物Na2SO4·10H2O和Na2CO3·10H2O代替自由水重复了上述反应。实验表明,足量的无盐水合物能在有机溶剂中可逆地失去自射所带的结晶水,因而能代替自由水来提代酶所需的"必需水",并有效地控制有机溶剂中酶促反应体系的水活度(αw)值,从而有利于肽键的形成。 相似文献
9.
水分子对磺酰脲类分子构效关系影响的研究 总被引:1,自引:0,他引:1
磺酰脲超高效除草剂是进入到植物体内抑制 ALS酶而起作用的 .其结构通式见 Scheme1 . 人们发现 ,在基本结构不变的前提下 ,Li 为 N或 C原子 ,R2 ,R4等的取代基不同将导致除草活性的差异 .而药物分子的构象与其生物活性密切相关 .大多数药物分子进入到植物体内后是在水相体系中与受体结合的 .探讨构效关系时 ,必须考虑水分子对药物分子构象的影响 [1] .本文首次报道在磺酰脲类分子中的有关研究 .1 研究对象及计算方法和过程1 .1 研究对象 对合成并进行生物测定的 35个磺酰脲类化合物 [2 ] 进行研究 ,其活性范围比较宽 ,p I5 0值 (… 相似文献
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G. Üstün S. Güner G. Arer S. Türkay A. T. Erciyes 《Applied biochemistry and biotechnology》1997,68(3):171-186
In an attempt to produce the polyunsaturated fatty acid (PUFA)enriched glycerides, commercially available Turkish anchovy
oil (PUFA content of 27%), was hydrolyzed with 1,3-specificRhizomucor miehei lipase. After the hydrolysis, the triglyceride (TG), diglyceride (DG), monoglyceride (MG), and free fatty acid (FFA) composition
of the reaction mixture was determined, and fatty acid components of these fractions were analyzed.R. miehei lipase released PUFA extremely slowly, resulting in their accumulation in the TG and DG fractions, especially in TG. The
PUFA content in the glyceride mixture (including TG, DG, and MG) increased as hydrolysis progressed. The effects of operational
parameters (pH, temperature, time, and enzyme concentration) on the extent of hydrolysis were investigated. Based on these
results, optimal reaction conditions were established. At optimal conditions (pH 4.0, 35°C, 3 h, and enzyme concentration
of 500 U/g oil), the level of PUFA in the glyceride mixture was raised to 40%. The individual TG and DG fractions contained
45 and 30% PUFA, respectively. Less than 2% of the total PUFA was lost in the FFA fraction. 相似文献
12.
The possible application of native lipase ofNigella sativa seed in the esterification of fatty acids to glycerol was investigated, and the effect of process parameters and the enzyme
selectivity on the reaction were determined. For this aim, the esterification of oleic acid, sunflower oil fatty acids, and
coco oil fatty acids with glycerol were studied. 相似文献
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A protocol that carboxylic acids esterifies with the quaternary ammonium salt of deep eutectic solvent (DES) is presented, which opens a new access to ester using DES as alkylating agent, solvent, and catalyst. The reaction runs smoothly in DES without any other additives. Substituted cinnamic acids, aromatic acids, and aliphatic acids can be esterified in moderate to good yields. The advantages of this reaction include excellent functional group compatibility and simple reaction procedure. 相似文献
14.
尿素包合法分离蚕蛹油中多不饱和脂肪酸 总被引:1,自引:0,他引:1
蚕蛹是缫丝副产品,我国每年副产近20万吨干蛹[1].蚕蛹中油脂含量相当丰富,约占蚕蛹干基的25%~29%,且油脂总量的71.0%为不饱和脂肪酸,这些不饱和脂肪酸在人体内可合成二十碳五烯酸及二十二碳六烯酸,与鱼油中的EPA,DHA具有相似的抗衰老、健脑益智的功能,能维持正常的肾脏功能,治腰背疼痛、肌肉无力,预防动脉硬化、血脂升高等血栓疾病[2]. 相似文献
15.
Fang Hua Zhang Yiping Xie Quanling Huang Xiaoyan Hong Zhuan 《Phosphorus, sulfur, and silicon and the related elements》2016,191(8):1075-1080
A series of novel compounds phosphoryl-containing polyunsaturated fatty acid derivatives n-(diisopropoxy-phosphonamide)-alkyl ester (2a–2o) have been synthesized and evaluated for lowering hypolipidemia activities. Amongst all the synthesized compounds, compound 2d, 2h, and 2m showed significant lowering of triglyceride (TG) by 47.37%, 45.88%, and 45.69%, respectively, in triton induced hyperlipidemic in mice. Furthermore, compound 2d showed potent antihyperlipidemic activity and was found to decrease the plasma total cholesterol levels (TC) by 53.3%, TG by 29.3%, in high-fat diet induced hyperlipidemic in mice. 相似文献
16.
De Angelis L Risé P Giavarini F Galli C Bolis CL Colombo ML 《Journal of mass spectrometry : JMS》2005,40(12):1605-1608
Algae from cold water (Canada) and warm water (China) were analyzed for their total lipid content, and for their fatty acid (FA) composition and content. The major findings are that FA from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n-3/n-6 FA ratio, and a higher degree of total unsaturation. The 18 C, 4 double bonds FA (18 : 4 stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n-3 FA in Canadian algae, suggests their possible utilizations for nutritional purposes. 相似文献
17.
Rong He Xiaogang You Hongye Tian Feng Gao Daxiang Cui Hongchen Gu 《Frontiers of Chemistry in China》2006,1(4):378-383
Nearly monodisperse CdSe quantum dots (QDs) have been prepared by a soft solution approach using air-stable reagents in different
organic solvents. This scheme is a supplement to the conventional thermal decomposition of organometallic compounds at higher
temperatures. CdSe nanocrystals of different sizes could be obtained by simply changing the solvent. This method is reproducible
and simple and thus can be readily scaled up for industrial production. The reaction process was monitored by the temporal
evolution of the UV-Vis absorption and room temperature photoluminensce spectra. The structures of the CdSe quantum dots were
determined by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The phase-transfer of oleic acid-stabilized
CdSe nanocrystals into PBS buffer solutions was also studied for their potentials in biological applications.
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Translated from Journal of Shanghai Jiaotong University, 2005, 39(1) (in Chinese) 相似文献
18.
Lipase-catalyzed esterification of selected phenolic acids with linolenyl alcohols was investigated in selected organic solvent
media. The enzyme activity for the esterification of dihydrocaffeic acid with linolenyl alcohol in solvent mixtures of hexane/2-butanone
of 75∶25 (v/v) and 65∶35 (v/v) was 0.88 and 0.47 μmol of esterified dihydrocaffeic acid/(g of solid enzyme·min), respectively,
with a corresponding esterification yield of 76 and 58%, respectively. However, the esterification of ferulic acid with linolenyl
alcohol in the reaction medium of hexane/2-butanone of 65∶35 (v/v) resulted in a low yield (16%). Using the reaction medium
of hexane/2-butanone of 75∶25 (v/v), an increase in linolenyl alcohol concentration with a concomitant use of a constant amount
of dihydrocaffeic acid resulted in an increase in esterification yield. The highest esterification yield of 99% was obtained
with a ratio of dihydrocaffeic acid to linolenyl alcohol of 1∶8 after 7 d of reaction. Biosynthesis of the end product, linolenyl
dihydrocaffeate, was confirmed by electrospray ionization mass spectroscopy structural analysis; the esterproduct demonstrated
an antiradical activity close to that of α-tocopherol. 相似文献
19.
Petr Huek Jacques A. Rijks Piet A. Leclercq Carl A. Cramers 《Journal of separation science》1990,13(9):633-638
Alkyl chloroformates with methyl, ethyl, and 2-chloroethyl substituents can instantaneously esterify fatty acids under proper reaction conditions. Apart from the formation of the corresponding alkyl esters, even the alkoxycarbonyl esters can be prepared. These derivatives are useful for the analysis of short-chain fatty acids. As alkoxycarbonyl ester, even acetic acid can already be separated from the solvent peak. The reaction conditions were examined, and the Influence of solvent polarity and reagent concentration on the conversion was studied. Quantitative conversion of acids to their easters was achieved in non-aqueous solutions, but even in the presence of water the yields were acceptable. 相似文献
20.
The kinetics of the esterification of lauric acid with geraniol catalyzed by a commercially immobilized lipase preparation
fromMucor miehei, Lipozyme, was studied in well-stirred flasks under conditions of no external mass transfer limitations. It was shown that
the reaction is inhibited by lauric acid and the reaction mechanism can be described as a Ping-Pong Bi-Bi with Dead-End inhibition
caused by lauric acid. 相似文献