脂肪组织甘油三酯酯酶研究进展

脂肪组织甘油三酯酯酶(ATGL)是新近发现的调节脂肪分解的关键酶,含有经典酯酶的Gly-X-Ser-X-Gly模序和α/β水解酶折叠子结构,其主要功能是催化甘油三酯水解的起始步骤,其信号传导途径也可能不同于激素敏感酯酶(HSL).文章就ATGL的近年研究进展进行了概述.     

Effects of Dietary Energy Level on the Expression of the HSL Gene in Different Tissues of Sheep

A total of 36 four-mon-old hybrid lambs (Dorset×Thin-tailed Han sheep) with similar body weight (BW) were randomly allocated to three dietary treatments with different energy (7.21,10.33 and 13.49 MJ d...     

酶法分离温州蜜柑汁囊的研究——Ⅰ、酶分离汁囊的效果及成因

用脂肪酶等四种生物酶分离温州蜜柑汁囊,结果表明:以脂肪酶分离温州蜜柑汁囊的得率达70%,果胶酶等三种酶分离汁囊的得率仅为38-40%。扫锚电镜观察发现未经酶作用的汁囊表面呈连续波纹状,由光滑均匀的蜡质覆盖,经酶处理后,蜡质呈无规则非连续网络状。     

Binding of lipase, amylase and protease to intestinal epithelium as affected by carbohydrates and lectins in vitro

Intraluminal digestive enzymes were shown to bind to chick intestinal epithelial surface (glycocalyx). Affinity of the intestinal epithelium for the enzymes decreased in the order, lipase > amylase > protease. The plant hemagglutinins, Con A, phytohemagglutinin, pokeweed mitogen and raw soybean effectively released lipase and amylase from the glycocalyx. Based on specific inhibition of binding by sugars, such as fucose and N-acetylated sugars, lipase and amylase appeared to be bound to blood group antigen-like sugar moieties on the glycocalyx of the microvilli.     

Preventive effect of Kaempferia parviflora ethyl acetate extract and its major components polymethoxyflavonoid on metabolic diseases

Previously, we reported that rhizome powder of Kaempferia parviflora Wall. Ex. Baker prevented obesity and a range of metabolic diseases. In this study, to clarify which molecular mechanisms and active ingredients of K. parviflora have an anti-obesity effect, we investigated the effect of ethyl acetate extract of K. parviflora (KPE) on TSOD mice, a spontaneously obese Type II diabetes model, and on pancreatic lipase. In the TSOD groups, KPE showed a suppressive effect on body weight increase and visceral fat accumulation and also showed preventive effects on symptoms related to insulin resistance, hypertension and fatty liver. In addition, KPE also suppressed body weight increase and food intake in TSNO mice groups, which served as reference animals, at an early stage of administration. Searching for the ingredients in KPE revealed that KPE contains at least 12 kinds of polymethoxyflavonoid (PMF). Furthermore, KPE and its component PMFs showed an inhibitory effect on pancreatic lipase. The above results suggest that KPE has a preventive effect on obesity and various metabolic diseases. The mechanisms of action probably involve inhibition of pancreatic lipase by the PMFs in KPE.     

Isolation of a novel catechin from Bergenia rhizomes that has pronounced lipase-inhibiting and antioxidative properties

An aqueous ethanol extract of Bergenia crassifolia rhizomes strongly inhibited human pancreatic lipase activity and increased scavenging of DPPH free radicals in vitro. Chromatographic separation of this extract led to isolation of the hydrolysable tannins (+)-catechin 3,5-di-O-gallate () and (+)-catechin 3-O-gallate (). This is the first report of the isolation of compound 1 from plant material. This compound strongly inhibited human pancreatic lipase (with an IC₅₀ value of 0.42 μg/ml) and exhibited a remarkable free radical-scavenging ability (with an SC₅₀ value of 1.04 μg/ml). The chemical structures of 1 and 2 were elucidated using MS, NMR and chemical approaches.     

制备生物柴油用脂肪酶产生菌的诱变和筛选

以提高全细胞生物催化制备生物柴油的效率为目的,采用紫外诱变的方法对产脂肪酶的米根霉菌株进行诱变和筛选。筛选得到的诱变株命名为LY6,脂肪酶水解酶活(4.33 U/mL)是原始菌株的4.33倍,合成酶活(0.28 U/mL)是原始菌株的1.12倍,脂肪酶水解酶最适反应pH值为7.0。将筛选得到的菌株制备成固定化全细胞生物催化剂催化大豆油转酯化制备生物柴油,在醇油比为3∶1(物质的量之比,下同)时,脂肪酸甲酯得率比原始菌株提高了41.0%,达到87.3%;在醇油比为4∶1时,最终生物柴油的甲酯得率比原始菌株提高了16.8%,达到96.1%,故经筛选得到的菌株能作为全细胞生物催化制备生物柴油的优良菌株。     

来源于解酯菌的嗜热耐碱脂肪酶的表达纯化及其酶学性质研究

脂肪酶广泛应用于食品加工、生物柴油制备等领域。为了有效提高微生物脂肪酶的可利用度,将来源于解酯嗜热菌(Thermosyntropha lipolytica DSM 11003)的脂肪酶基因(tll2)克隆到大肠杆菌表达载体pET28a中,获得重组质粒pET28a TLL2,将pET28a TLL2转入大肠杆菌BL21(DE3)宿主菌中进行高效表达。通过热处理和镍柱亲和层析得到电泳纯的蛋白TlLip2,对其进行酶学性质表征。结果显示,TlLip2的亚基分子质量为57 ku,比酶活为31 U/mg,最适反应pH及温度分别为8.0和60℃。在60℃以下、pH 6.0~11.0范围内,TlLip2的稳定性较好,相对酶活均维持在60%以上。金属离子K+和Na+对TlLip2有较大激活作用,而Co^2+、Zn^2+、SDS和Tween 80对TlLip2酶活力抑制作用明显。TlLip2在极性小的有机溶剂中具有较好的耐受性。TlLip2对中等碳链长度的对硝基苯酯显示出更高的活性,其中以对硝基苯己酯为底物时,TlLip2的酶活最高;以对硝基苯棕榈酸酯为底物时,该酶的动力学常数Km为0.29 mmol/L,Vmax为2.28 mmol/(L·min^-1),kcat为6.19 s^-1。此外,将其应用到油酸乙酯的合成研究中,以油酸和乙醇为底物,研究TlLip2催化制备油酸乙酯的转化条件,结果表明在60℃、加酶量为100 U/g的TlLip2,催化摩尔比为1∶2的油酸和乙醇,12 h后油酸乙酯的转化率达到62.1%,表明TlLip2在催化脂肪酸酯化方面具有较大的应用潜能。     

基于BP神经网络的脂肪酶酯化菜籽油脱臭馏出物的仿真研究

该文采用BP神经网络对脂肪酶催化酯化菜籽油脱臭馏出物的工艺条件进行了仿真研究。将中心组合试验和神经网络相结合,采用动量梯度下降法对网络进行训练仿真,并利用训练好的网络对催化酯化工艺条件进行预测。结果表明：经过训练的网络可以很好的模拟反应条件,得到了脂肪酶催化反应的最佳工艺参数,此时脂肪酸甲酯的含量为55.2%,维生素E保留率达到90%,为脱臭馏出物的酯化催化效果的预测提供了一条可行的途径。