共查询到20条相似文献,搜索用时 46 毫秒
1.
手性醇是重要的医药中间体与精细化工品,立体选择性羰基还原酶催化制备手性醇具有重要的研究与应用价值,受到国内外科学家和工程师的高度关注。本文主要围绕羰基还原酶的发现与分类、催化羰基还原反应的活性与立体选择性机制、酶的筛选挖掘与分子改造技术、辅酶还原型烟酰胺腺嘌呤二核苷酸(磷酸)的再生方法、羰基还原酶催化合成手性醇医药中间体与精细化学品技术开发与应用等方面展开综述。重点阐述了羰基还原酶催化制备降血脂、抗细菌或病毒感染、抗肿瘤、抗抑郁症、抗癫痫等重要疾病治疗药物中间体及脂肪族、芳香族手性醇精细化工品的国内外技术进展与应用,为高效能立体选择性生物催化剂的创制和手性化合物的生物合成提供理论借鉴和成功范例。 相似文献
2.
3.
4.
实验研究了表面活性剂(SDS,CTAB,Emulsifier OP-6)对面包酵母细胞催化2-辛酮不对称还原反应的影响.结果表明,当底物浓度为10mmol/L时,在不含表面活性剂的体系中,副反应和逆反应使反应96h后的得率和产物(S)-2-辛醇对映体过量率(Enantiomeric Excess,e.e.)仅为77.4%和78.8%.一定浓度的表面活性剂可提高正反应速率、降低逆反应和副反应速率,在含0.4mmol/L Emulsifier OP-6或0.04mmol/L CTAB的体系中反应96h,得率分别达到88.4%和91.1%,产物e.e.值为97.0%和94.5%.反应得率和产物e.e.值提高与表面活性剂对细胞生长、细胞膜透性的改变有关.EmulsifierOP-6的作用效果优于其他2种表面活性剂. 相似文献
5.
通过醛基还原酶和6-磷酸葡萄糖脱氢酶的基因构建重组大肠杆菌,并考察加入诱导剂的时间、浓度和诱导时间对酶活的影响,优化重组大肠杆菌的表达。实验结果表明,重组大肠杆菌在对数生长中期加入0.4 mmol/L的诱导剂,在32℃下培养8 h,酶活可达到5.27 U/mg-protein。以重组大肠杆菌为催化剂,研究4-氯乙酰乙酸乙酯转化为-R( )-4-氯-3-羟基丁酸乙酯的反应,发现利用基因重组技术构建的大肠杆菌,可使醛基还原酶和葡萄糖脱氢酶共同表达,实现辅酶再生,提高产物对映体过量值。在转化反应过程中,随着温度升高,产物收率先增加;当转化温度在32℃以上,收率反而会下降。底物对反应有抑制作用,采用分批加入底物的方式可以减少抑制作用,提高产物收率。 相似文献
6.
综述了有机合成领域中,通过炔烃立体选择性还原制备了Z-或E-烯烃的近期方法。 相似文献
7.
研究有机溶剂中面包酵母催化2-氧代-4-苯基丁酸乙酯(OPBE)不对称还原合成标题化合物((R)-HPBE),分别考察用干酵母和湿酵母作催化、底物浓度、反应体系和湿酵母保存时间等凶素对OPBE转化率(X<,OPBE>)、HPBE产率(Y<,HPBE>)及(R)-HPBE的光学纯度(e.e.%)的影响.实验结果表明,湿酵母的立体选择性好于干酵母,但转化率和产率很低;乙醚为湿酵母催化较为适宜的介质.另外,湿酵母培养好后应立即反应. 相似文献
8.
从近平滑假丝酵母(Candida parapsilosis CCTCC 203011)中分离得到了新的NADPH依赖型羰基还原酶。粗酶经硫铵分级沉淀、DEAE Sepharose离子交换层析、Phenyl-sepharose FF疏水层析、Blue Sepharose FF亲和层析后在SDS-PAGE上显示为单一条带,其酶蛋白的相对分子质量为30 kD。该酶还原反应的最适pH值为4.5,最适温度为35 ℃,Cu2+对羰基还原酶有强烈的抑制作用。该酶具有较高的底物专一性和立体选择性,对α-羟基苯乙酮和4-氯乙酰乙酸乙酯具有较高的不对称还原活力,其产物分别为(S)-苯基乙二醇和(R)-4-氯-3-羟基丁酸乙酯,e.e值分别为100%和94.3%。因此该酶蛋白是不对称合成手性醇有效的生物催化剂之一。经LC-MASS-MASS分析得到了酶蛋白中一个肽段的氨基酸序列,通过比对发现该酶与假定蛋白(hypothetical protein CaO19.10414)具有一定的同源性。 相似文献
9.
10.
生物不对称合成R-(-)-扁桃酸的影响因素 总被引:10,自引:0,他引:10
研究了酵母细胞(Saccharomyces cerevisiae)生物不对称还原苯乙酮酸合成R-(-)-扁桃酸的过程中,环境因子对底物的转化效率和产物对映体过量值的影响. 结果表明,高浓度的底物苯乙酮酸对酵母细胞的催化还原活性具有较显著的抑制效应. pH 6.5、温度32℃、严格厌氧为较适宜条件,底物苯乙酮酸的转化率和产物扁桃酸的得率分别可达97.0%和96.1%,R-(-)-扁桃酸的对映体过量值(ee)为95.1%. 相似文献
11.
12.
13.
14.
15.
以咪唑类离子液体/水两相为反应体系,考察了咪唑类离子液体的不同咪唑环取代烷基链、离子液体与水相的体积比、反应温度、摇床转速和水相pH对酵母Candida Pseudotropicalis催化还原2'-氯-苯乙酮制备S-2'-氯-苯乙醇反应的影响。结果表明,随着离子液体咪唑环上取代烷基的增大,S-2'-氯-苯乙醇的收率呈下降趋势。以1-己基-3-甲基咪唑六氟磷酸盐/水两相为反应体系,在2'-氯-苯乙酮初始浓度为3 g/L,辅助底物葡萄糖浓度为50 g/L的条件下,较合适的反应条件为离子液体与水的体积比1:50,水相pH值6.8,反应温度30℃,摇床转速200 r/min,反应24 h,产物S-2'-氯-苯乙醇产率可达85.9%,ee值大于99.9%。酵母细胞催化剂的重复使用实验表明,随着使用次数增加,离子液体/水两相体系中酵母细胞的催化作用明显下降。 相似文献
16.
17.
《分离科学与技术》2012,47(7-9):1473-1490
Abstract Pritchard et al. observed the phenomenon that the flux began to rise when the baker's yeast suspension was concentrated to a very high concentration in a thin-channel membrane module under laminar conditions. A further investigation of this interesting finding through both filtration experiments and rheological measurements has been conducted using baker's yeast suspensions. The separate filtrations of the suspensions and their supernatants suggest that for baker's yeast suspensions at very high concentrations there might be no cake layer. On the basis of the above results, an alternative to the normal membrane concentration process is put forward. Using this novel approach, particularly in its batch mode, a low-concentration feed can be directly transferred into a high-concentration product at a much higher flux. 相似文献
18.
Baker’s yeast number 6 was selected by screening. It showed good catalytic activity and enantioselectivity for asymmetric reduction of 2,5-hexanedione to produce (2S,5S)-2,5-hexanediol. Gas chromatography-mass spectrometry (GC-MS) revealed that the intermediate was (S)-5-hydroxyhexane-2-one. Reduction of 2,5-hexanedione proceeded in a two-step reaction. The hydroxyketone was initially formed, and this intermediate was further re-duced to the diol. Factors influencing the product yield and the enantiomeric excess of the reduction of 2,5-hexandione catalyzed by baker’s yeast number 6 were investigated. Higher concentration (≤100 mmol8226;L-1) of 2,5-hexandione did not influence 5-hydroxyhexane-2-one production, but 2,5-hexanediol production was inhibited by excess accumulation (>30 mmol8226;L-1) of intermediate. The optimal conditions were glucose as the co-substrate at an initial glucose concentration of 20 g8226;L-1, 3461616;C, pH 7.0 and cell concentration 60 g8226;L-1 (cell dry mass). Under the optimal condition and an initial substrate concentration of 30 mmol8226;L-1, the yield of 2,5-hexandiol was 78.7% and the enantiomeric excess of (2S,5S)-2,5-hexandiol was 94.4% for 24-h reduction. 相似文献
19.
Leavening activity is an important quality index in the baker's yeast industry. In this work, Taguchi's experimental design was used to investigate the effect of important factors on the leavening activity of Saccharomyces cerevisiae during spray drying. Feed rate and inlet air temperature are the most important factors in spray drying of baker's yeast. The amount of starch as a processing aid also has a considerable effect on the leavening activity of the yeast. 相似文献
20.
Properly chosen additives (carriers) can protect the material or decrease water content in it. The papcr presents results of measurements of sorption isotherms of baker's yeast Saccharvmyces cerevisiae dried in an oven dryer and in a fluidized bed with and without carriers. The authors propose an original method for calculation of sorption isotherms for multicomponent mixtures containing yeast. Results of the calculations were compared with experimental data. 相似文献