用生物技术合成纯单甘酯

通常用化学方法生产单甘酯，由于高温酯化产物中单甘酯含量不高，必须通过高真空的分子蒸馏过程才能获得纯度较高的单甘酯。这种方法不仅能耗高，而且单甘酯产率较低。最近国外油脂工作者利用1．3一位专一性脂酶为催化剂，使脂肪酸，或脂肪酸的酷类与甘油反应，合成高纯度的1（3）一单甘酯。尤其是利用天然植物油与甘油为原料。利用这种生物技术，可以直接获得纯度高于95％的1（3）一单甘酯，而且单甘酯产率大于85％，本文简要介绍这种新的生物合成技术与结果。合成方法商品固定化酸酶Lipozyme，（来自微生物脂酶）。卧基供体包括：月桂酸…     

相转移剂存在下大豆油脂肪酸单甘脂的合成

以大豆油和甘油为原料,研究了碱催化下大豆油甘油解生成脂肪酸单甘脂的合成反应。同时,利用单因素试验对影响单甘脂质量分数的几种重要因素(如反应温度、催化剂、相转移剂、碱用量、反应时间、反应物料物质的量比)进行讨论,通过正交试验,确定了制备大豆油脂肪酸单甘酯的最佳工艺条件:甘油与大豆油物质的量比为2.5∶1,0.4%的NaOH为催化剂,辅以0.4%的四丁基溴化铵为相转移催化剂,于反应温度200℃下反应时间3 h,得到单甘酯的质量分数为62.6%,为单甘脂的合成提供了一种改进的方法。     

温度对单甘酯的合成起关键作用

在无溶剂体系中以脂肪酶催化棕榈油的甘油解反应合成单甘酯时，发现温度对单甘酯的产率起关键作用。反应存在一临界温度，低于临界温度时单甘酯的平衡浓度高于６０％，而高于临界温度时单甘酯含量只有３０％左右。临界温度与油脂的种类有关；通过测定各种油脂的临界温度并与其熔点相比较，结合反应现象学及反应进程中反应混合物各组分含量的变化，提出了临界温度的存在机理。     

固体超强酸催化大豆油和大豆油脂肪酸酯化与酯交换制备单甘酯的研究

采用固体超强酸催化大豆油和大豆油脂肪酸与甘油酯化和酯交换制备单甘酯,通过二级分子蒸馏纯化单甘酯。通过响应面优化得到的最佳条件为：大豆油30.0 g,大豆油脂肪酸20.0 g,反应温度200℃,固体超强酸催化剂添加量0.26%（占大豆油和大豆油脂肪酸质量）,甘油添加量12.66 g和反应时间4.81 h。在最佳条件下,反应得到的甘油酯混合物中,单甘酯含量达到69.82%。甘油酯混合物在Ⅰ级135℃分子蒸馏除去游离脂肪酸和甘油,在Ⅱ级185℃分子蒸馏蒸出单甘酯,得到产品中单甘酯含量为96.54%。     

中心组合设计优化红花油脂肪酸单甘酯的合成条件

采用中心组合设计法研究了合成红花油脂肪酸单甘酯的三个关键因子:碱催化剂用量wt%、反应温度℃、甘油与红花油的摩尔比对其产率的影响,得到了三因子与单甘酯产率的回归方程以及三因素之间相互作用的响应面图。优化结果表明,碱催化剂用量为0.142%、反应温度194.3℃、甘油与红花油摩尔比3.05时,红花油脂肪酸单甘酯产率可达64.8%,比正交实验结果(62.54%)提高3.6%。     

离子液体中酶法酯化选择性富集单甘酯的研究

系统地探究了离子液体的溶剂性质对酶法酯化反应中选择性富集单甘酯的影响。结果表明,离子液体的极性和氢键性质是影响选择性富集单甘酯的决定因素。在[Tf_2N]~-类离子液体中,E_N~T值与单甘酯选择性呈现明显的正相关性。具有羟基功能基团的离子液体[HO(CH_2)_2MIM]Tf_2N以及具有强氢键碱性的阴离子离子液体[BMIM]N(CN)_2有很高的单甘酯选择性。[PF_6]~-和[Tf_2N]~-类离子液体由于具有较高的log P值和较低β值,因此具有较高的脂肪酸转化率。[PF_6]~-离子液体过高的黏度提高了反应的传质阻力,使脂肪酸转化率降低,单甘酯选择性升高,呈现与极性规律相反的规律。选择[HO(CH_2)_2MIM]Tf_2N作为反应溶剂,得到合成单甘酯的最佳工艺条件为底物(甘油与油酸)摩尔比4∶1、反应时间8 h、脂肪酶添加量4%、离子液体添加量30%、反应温度50℃。在最佳条件下脂肪酸转化率为93.6%,单甘酯含量为61.1%,单甘酯选择性为64.5%。     

具有保健功能的甘油脂肪酸酯

本文将具有保健功能的甘油脂肪酸酯分为甘三酯、甘二酯、甘一酯(单甘酯)分别加以详细介绍。文中所述物质既有正处于实验阶段或已工业化生产的产品，也有作者预测的尚未出现的物质。     

米糠油酶法酯化脱酸的研究

通过添加单甘酯和甘油混合物,以Lipozyme TLIM为催化剂对米糠油酶法酯化脱酸进行了研究。分别考察了反应温度、反应时间、催化剂添加量、单甘酯和甘油混合物添加量,单甘酯和甘油的比例对酸价的影响。由单因素和响应面试验得出酶法酯化脱酸反应的最佳条件为温度65℃,反应时间9.3 h,催化剂添加量10%,单甘酯和甘油的添加量为150%,单甘酯和甘油的比例为1∶1。在此条件下酸值由原料的43.0 mg/g降至7.2 mg/g。     

分子蒸馏单甘酯的近况与发展(二)

３分子蒸馏单甘酯的生产工艺３．１工艺方法分子蒸馏单甘酯的生产工艺包括单甘酯合成、采用分子蒸馏技术分离出纯单甘酯及产品喷雾冷凝包装３个部分。单甘酯合成工艺主要采用酯化和醇解两种工艺。经过合成单甘酯工艺得到中间产品实际上是单脂肪酸甘油酯、二脂肪酸甘油酯、...     

酶促玉米油甘油解制备双、单甘酯

了以１６１９脂肪酶为催化剂,用玉米油甘油解制备双,单甘酯的影响因素,试验结果表明,适宜的工艺条件,ＰＨ值７．５甘油含水量５．５％,酶浓度４００－６００／ｇ脂肪,玉米油甘油摩尔比１：１,反应温度２０℃,搅拌速度７２０ｒ／ｍｉｎ。在上述条件下反应８ｈ,双、单甘酯含量〉７６％。同时,报道了反应进程的监测和产品分析方法。     

双元配体转光剂的合成及其在防紫外线织物中的应用

本文讨论了使用固相和液相两种合成方法,合成稀土金属有机配合物防紫外转光剂材料。通过对比固相和液相合成转光剂的红外谱图、水溶液中的分散性能、对织物的防紫外效果,发现液相合成方法中稀土金属铕离子与有机配体分子结合更充分,液相合成的转光剂材料在水溶液中更易于分散均匀,其提升织物防紫外效果更加显著。     

Effect of caseinophosphopeptides added to fruit beverages upon ferritin synthesis in Caco-2 cells

Ferritin synthesis was evaluated in iron sulphate solutions and in fruit beverages supplemented with iron, with/without zinc in the presence of caseinophosphopeptides (CPPs), based on a system combining simulated gastrointestinal digestion and the Caco-2 cell model. In iron sulphate solutions with/without zinc, the addition of CPPs had no effect upon ferritin synthesis. When CPPs were added to the bioaccessible fraction of fruit beverages supplemented with iron, ferritin synthesis increased in the same proportion as with the addition of milk. The addition of zinc to fruit beverages supplemented with iron and to iron sulphate solutions decreased ferritin synthesis. Nevertheless, in fruit beverages with milk, this decrease in ferritin synthesis was not observed when zinc was present.     

酶法合成生物表面活性剂

总结了外源酶催化法和整胞微生物代谢法合成生物表面活性剂的特点,并将外源酶催化法对整胞微生物代谢法及传统化学合成法的优势进行了比较.详细介绍了单甘酯、糖酯、(溶血)磷脂、纯异头烷基糖苷和氨基酸型表面活性剂等生物表面活性剂的酶催化合成方法及其研究进展;展望了酶工程的进步、化学 酶催化技术进展、外源多酶联合催化技术的开发与应用、酶膜反应器和其它连续酶反应器的开发,以及反应 分离耦合技术在酶催化过程中的应用将给酶法合成生物表面活性剂带来的机遇.     

非水介质中脂肪酶催化合成酯类的研究进展

生物催化是酶工程学的研究重点之一.脂肪酶的来源广泛,底物特异性多样化,它在生物催化中的研究和应用尤为引人注目,利用脂肪酶合成酯类已成为研究的热点之一.本文综述了脂肪酶在有机相溶剂中催化酯类合成的反应机理、相对于化学合成酶法合成的优点以及脂肪酶合成酯类的研究进展.并探索提出了改进该方法的一些想法,以期使酶合成法可以逐步取代化学合成法.     

Biosynthesis of phytochelatins in the fission yeast. Phytochelatin synthesis: a second role for the glutathione synthetase gene of Schizosaccharomyces pombe

By complementation screening of a cadmium-sensitive Schizosaccharomyces pombe mutant deficient in phytochelatin synthesis, but with 44% of the wild-type glutathione content, we cloned a DNA fragment involved in phytochelatin synthesis. Sequence analysis revealed that it encodes the second enzyme involved in glutathione (GSH) biosynthesis, glutathione synthetase (GSH2) (E.C.6.3.2.3, Wang and Oliver, 1997). The mutant allele shows a single base-pair exchange at the 3' end of the reading frame leading to a single amino acid change from glycine to aspartate. This mutation leads to a significant reduction of phytochelatin synthesis, whereas glutathione synthesis is impaired to a far lesser extent. Complementation with the Arabidopsis thaliana GSH2 cDNA led to a partial restoration of phytochelatin synthesis. These data strongly suggest that the GSH2 gene encodes a bifunctional enzyme that is able to catalyse both the synthesis of GSH by adding glycine to the dipeptide (gammaGlu-Cys) and the synthesis of phytochelatins. The sequence has been submitted to EMBL, Accession No. Y08414.     

Effect of sialoadenectomy on the ability of mouse serum to induce deoxyribonucleic acid synthesis in mammary epithelial cells: possible role of epidermal growth factor

Serum was collected from sham-operated or sialoadenectomized mice and added to serum starved cultures of normal mouse mammary epithelial cells. Synthesis of DNA, estimated with a pulse of 1 microCi/ml [3H]thymidine between 17 and 18 h after adding serum, was increased by serum. Sialoadenectomy did not affect the ability of low serum concentrations (less than 4%) to increase DNA synthesis, but DNA synthesis induced by higher serum concentrations was reduced by sialoadenectomy. Physiological concentrations of epidermal growth factor restored the ability of serum from sialoadenectomized mice to increase DNA synthesis. Antiepidermal growth factor reduced DNA synthesis in cultures treated with high concentrations of serum from sham-operated mice, but not in cultures treated with serum from sialoadenectomized mice. Time course studies indicated that the time of maximum DNA synthesis was similar between cultures treated with serum from sham-operated and sialoadenectomized mice. Treatment with serum from sialoadenectomized mice for 4 d resulted in lower cell number than did treatment with serum from sham-operated mice. This effect of sialoadenectomy could be overcome by epidermal growth factor. These data indicate that sialoadenectomy, which has previously been shown to depress mammary gland development, alters the endocrine status of mice, such that serum from sialoadenectomized mice is less effective in inducing DNA synthesis by mammary epithelial cells. These differences in ability of serum to induce DNA synthesis can be explained by differences in epidermal growth factor concentration or the concentration of epidermal growth factor-like constituents.     

蛹虫草虫草素合成代谢网络及其关键节点的研究进展

虫草素（Cordycepin）是虫草属（Cordyceps）真菌产生的核心高附加值次级代谢产物之一。与其他工业菌种相比,蛹虫草在腺苷结构类似物（如虫草素）合成方面有天然的代谢通量优势。近年,随着组学分析技术和蛹虫草基因编辑技术的发展,蛹虫草虫草素合成代谢网络,尤其是关键的底物合成途径得到了完整的解析。因此,该综述对目前已知的蛹虫草虫草素合成代谢网络进行了模块化梳理,将其划分为中心碳代谢途径、单磷酸肌苷（Inosinate,IMP）途径和虫草素底物合成途径,并分析了前体物质组成和多个分散途径、关键节点对虫草素合成的影响,系统阐述了IMP物质的合成与流向,佐证了IMP的合成与代谢是虫草素合成的关键节点,为未来通过代谢工程与合成生物学策略优化蛹虫草虫草素代谢网络、构建稳定高产虫草素的蛹虫草菌株提供相对详实的背景参考。     

Features of nutrition and biosynthesis of protein in animals of various ages

Age-dependent features of protein synthesis intensity were studied in tissues (liver, muscles, plasma) by the method of continuous constant L-(1-14C)-leucin infusion. The investigation was conducted in male rats aged 4 and 24 months that were bred in large and small holes, and received rations with varying protein content (2.5, 15 and 60% of casein). It has been shown that protein synthesis intensity in the tissues studied is not lowered with age, in the liver it is higher than in the muscles. Differences in the early postnatal nutrition (breeding of the animals in large and small holes) has not influenced protein synthesis in the tissues. A tendency has been observed to activation of protein synthesis in the liver with lowering protein level in the diet.     

外源脱落酸对发芽玉米籽粒中类胡萝卜素合成的影响

为研究脱落酸（abscisic acid,ABA）及抑制剂钨酸钠（Na2WoO4）处理对发芽玉米中类胡萝卜素合成的影响,以‘苏玉29’黄色玉米为材料,将其进行不同质量浓度外源ABA浸泡处理后进行发芽,测定发芽玉米中可溶性蛋白、游离氨基酸、脯氨酸、VC、总酚、抗氧化酶活性、抗氧化能力、类胡萝卜素含量及类胡萝卜素合成基因表达量。结果表明,与对照组相比,ABA处理能提高发芽玉米中可溶性蛋白、游离氨基酸、脯氨酸、VC、总酚的含量和内源ABA含量;5 mg/L ABA条件下,类胡萝卜素含量达到最高,叶黄素和玉米黄质分别较对照组提高了27.6%和20.1%,而Na2WoO4会抑制内源ABA的合成,同时降低类胡萝卜素含量。实时聚合酶链式反应结果表明,ABA处理能够显著提高发芽玉米类胡萝卜素合成基因的表达量。同时,发芽玉米籽粒中抗氧化酶活性及抗氧化能力明显增强。综上,外源ABA处理能够促进发芽玉米内源ABA合成,提高发芽玉米类胡萝卜素合成基因的表达,促进发芽玉米中类胡萝卜素的合成,增强发芽玉米抗氧化能力,提高发芽玉米籽粒的营养品质。     

L-抗坏血酸棕榈酸酯的合成研究进展

L-抗坏血酸棕榈酸酯是优良的天然抗氧化剂。综述了L-抗坏血酸棕榈酸酯合成研究进展，归纳了L-抗坏血酸棕榈酸酯的几种合成方法，如化学合成法和酶催化法，为其合成研究提供一些线索。