CTAB混合反胶团萃取工业脂肪酶

研究了CTAB与Tween、含氧有机物形成的混合反胶团对工业脂肪酶进行萃取分离的效果. 实验表明,CTAB-Tween85和CTAB-含氧有机物混合反胶团的萃取率高于单一CTAB反胶团;反萃时CTAB-含氧有机物混合反胶团的反萃率与单一CTAB反胶团的反萃率相似,CTAB-Tween60和Tween40混合反胶团的反萃效果优于单一CTAB反胶团. 通过测定反萃水相的酶活,发现CTAB-TRPO混合反胶团的效果最好,酶活回收率最高,可以达到70%.     

In Silico Study,Physicochemical, and In Vitro Lipase Inhibitory Activity of α,β-Amyrenone Inclusion Complexes with Cyclodextrins

α,β-amyrenone (ABAME) is a triterpene derivative with many biological activities; however, its potential pharmacological use is hindered by its low solubility in water. In this context, the present work aimed to develop inclusion complexes (ICs) of ABAME with γ- and β-cyclodextrins (CD), which were systematically characterized through molecular modeling studies as well as FTIR, XRD, DSC, TGA, and SEM analyses. In vitro analyses of lipase activity were performed to evaluate possible anti-obesity properties. Molecular modeling studies indicated that the CD:ABAME ICs prepared at a 2:1 molar ratio would be more stable to the complexation process than those prepared at a 1:1 molar ratio. The physicochemical characterization showed strong evidence that corroborates with the in silico results, and the formation of ICs with CD was capable of inducing changes in ABAME physicochemical properties. ICs was shown to be a stronger inhibitor of lipase activity than Orlistat and to potentiate the inhibitory effects of ABAME on porcine pancreatic enzymes. In conclusion, a new pharmaceutical preparation with potentially improved physicochemical characteristics and inhibitory activity toward lipases was developed in this study, which could prove to be a promising ingredient for future formulations.     

磁性淀粉微球固定化脂肪酶的研究

磁性淀粉微球为载体,采用戊二醛交联法固定化脂肪酶。磁性淀粉微球的主要组成是淀粉和磁粉。结果得到,磁性固定化脂肪酶的总活力、蛋白载量、比活、活性回收率、最适温度和最适pH值分别为4897.15U/g、50.59mg/g、98.58U/mg、72.73%、45℃和8.0。Ca2+、Na+和Mg2+对固定化脂肪酶和自由酶有激活作用,作用大小顺序为Ca2+>Mg2+>Na+。Cu2+和Fe2+对固定化脂肪酶和自由酶有抑制作用,Cu2+的作用尤其明显。脂肪酶被固定化后其热稳定性(在水介质和正己烷中)、操作稳定性、pH稳定性均比自由酶明显提高。固定化脂肪酶和自由酶在4℃下,pH8的PBS和正己烷中保存34d后,其相对活力分别是78.3%和98.8%。     

有机相脂肪酶催化合成阿魏酸乙酯

本实验研究了有机溶剂中脂肪酶催化阿魏酸乙酯合成反应。对催化合成阿魏酸乙酯反应的脂肪酶和反应介质进行了比较,最佳溶剂为叔丁醇,在所选的6种脂肪酶中,固定化于大孔丙烯酸树脂的南极假丝酵母脂肪酶B(Novozym 435)的催化活性最好。同时对影响合成阿魏酸乙酯反应的因素(底物浓度、底物摩尔比、温度、初始水含量、反应时间等)进行了探讨,优化了反应条件:在10ml无水叔丁醇中,当酸醇摩尔比为1:1,酸浓度为0.1mol/L,反应温度为60℃,反应时间为120h时产率达到最高,脂肪酶Novozym 435具有较高的稳定性,重复使用六次后产率仍然可达到23%。     

介孔分子筛SBA-15表面改性对脂肪酶固定化的强化作用

引言 脂肪酶可以催化酯水解或醇解、酯合成、酯交换、多肽合成及高聚物合成等多种有机反应,已被广泛应用于食品、精细化工及制药工业中[1].作为重要的生物催化剂,脂肪酶应用的有效性和经济性很大程度上取决于酶的固定化.     

生物酶法转化酵母油脂合成生物柴油

以一株高产油脂圆红冬孢酵母菌(Rhodosporidum toruloides Y4#)干菌粉为原料,利用酸热法提取了该酵母油脂,并对所得油脂进行了分析. 进一步利用该酵母油脂为原料分别研究了无溶剂体系中三步甲醇法及在叔丁醇介质体系中脂肪酶催化合成生物柴油,发现脂肪酶可以有效转化该酵母油脂制备生物柴油. 在优化反应条件下,生物柴油得率可达90%左右,略低于相同条件下利用精制大豆油合成生物柴油的得率.     

Candida sp.脂肪酶的纯化及其性质

采用简单的两步法-离子交换层析和疏水层析法,对Candida sp. 99-125脂肪酶进行了纯化,比活提高了10.0倍,达到27200 U/mg,回收率为35.5%. SDS-PAGE电泳分析显示该酶的分子量约为38 kDa. 酶学性质研究表明,该酶最适反应温度为40℃,最适反应pH值为8.5,在室温下具有良好的稳定性. 钙离子和Tween80能够促进提高脂肪酶的活性,而铁离子、铜离子和SDS对其有明显的抑制作用.     

Biofuel production from spent coffee grounds via lipase catalysis

Lipases namely Mucor miehei, Pseudomonas cepacia, Rhizopus delemar, Geotrichum candidum, Candida rugosa, Porcine pancreas-II, Pseudomonas fluorescence, and Candida antarctica lipase-B (Novozyme-435) were employed for biodiesel synthesis from spent coffee oil. Around 96% oil-to-biodiesel conversion was obtained using Novozyme-435 as a catalyst at 1:5 oil-to-methanol molar ratio and 40ºC. Total spent coffee grounds generated at the North-West University, Potchefstroom Campus (NWU PC) was estimated which could be used to produce 162 L of biodiesel. A waste valorization strategy was devised for converting organic wastes produced at the NWU PC to bioenergy.     

Enzymatic enrichment of arachidonic acid from Mortierella single-cell oil

An attempt was made to enrich arachidonic acid (AA) from Mortierella single-cell oil, which had an AA content of 25%. The first step involved the hydrolysis of the oil with Pseudomonas sp. lipase. A mixture of 2.5 g oil, 2.5 g water, and 4000 units (U) Pseudomonas lipase was incubated at 40°C for 40 h with stirring at 500 rpm. The hydrolysis was 90% complete after 40 h, and the resulting free fatty acids (FFA) were extracted with n-hexane (AA content, 25%; recovery of AA, 91%). The second step involved the selective esterification of the fatty acids with lauryl alcohol and Candida rugosa lipase. A mixture of 3.5 g fatty acids/lauryl alcohol (1:1, mol/mol), 1.5 g water, and 1000 U Candida lipase was incubated at 30°C for 16 h with stirring at 500 rpm. Under these conditions, 55% of the fatty acids were esterified, and the AA content in the FFA fraction was raised to 51% with a 92% yield. The long-chain saturated fatty acids in the FFA fraction were eliminated as urea adducts. This procedure raised the AA content to 63%. To further elevate the AA content, the fatty acids were esterified again in the same manner with Candida lipase. The repeated esterification raised the AA content to 75% with a recovery of 71% of its initial content.     

Effects of Additives on the Activity and Enantioselectivity of Candida rugosa Lipase in a Biphasic Medium

The effects of Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺ ions on the activity and enantioselectivity of Candida rugosa lipase (CRL) were investigated in a biphasic medium composed of phosphate buffer solution (containing a metal ion within a 50–500 mM concentration range) and isooctane. The hydrolytic activities of CRL towards p‐nitrophenyl acetate were measured after incubation of the enzyme in the presence of metal ions for 24 h, and they were compared to that obtained after incubation in the absence of any metal ion. The CRL activity was stimulated by the chloride salts of Li⁺, K⁺ and Mg²⁺ for all concentrations considered and the highest enhancement was achieved by Li⁺ with a 1.24–1.75 fold increase observed. The effects of metal ions on the enantioselectivity of CRL were investigated by performing the hydrolysis of racemic Naproxen methyl ester in the same biphasic medium containing Li⁺, Na⁺, K⁺, Mg²⁺ and Zn²⁺ ions. The addition of metal ions increased the hydrolysis rate by ca. 1.31–1.45 fold relative to the control, whereas the enantiomeric excess of product increased slightly in the presence of the metal ions. The effect of Triton X‐100 on the activity and enantioselectivity of the CRL was also investigated by employing 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 mM concentrations of it in phosphate buffer solution of the biphasic medium. High concentrations of Triton X‐100 stimulated the enzyme activity up to 1.66 fold after 24 h incubation. Triton X‐100 increased the hydrolysis rate almost independently of the concentration.