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1.
The aim of this work is to discover the inhibitory mechanism of tea peptides and to analyse the affinities between the peptides and the angiotensin-converting enzyme(ACE) as well as the stability of the complexes using in vitro and in silico methods. Four peptide sequences identified from tea, namely peptides I, II, III, and IV, were used to examine ACE inhibition and kinetics. The half maximal inhibitory concentration(IC_(50)) values of the four peptides were(210.03±18.29),(178.91±5.18),(196.31±2.87), and(121.11±3.38) μmol/L, respectively. The results of Lineweaver-Burk plots showed that peptides I, II, and IV inhibited ACE activity in an uncompetitive manner, which requires the presence of substrate. Peptide III inhibited ACE in a noncompetitive manner, for which the presence of substrate is not necessary. The docking simulations showed that the four peptides did not bind to the active sites of ACE, indicating that the four peptides are allosteric inhibitors. The binding free energies calculated from molecular dynamic(MD) simulation were-72.47,-42.20,-52.10, and-67.14 kcal/mol(1 kcal=4.186 kJ),r espectively. The lower IC_(50) value of peptide IV may be attributed to its stability when docking with ACE and changes in the flexibility and unfolding of ACE. These four bioactive peptides with ACE inhibitory ability can be incorporated into novel functional ingredients of black tea.  相似文献   

2.
阿尔茨海默病(Alzheimer's disease,AD)是全球共同关注的重大公共卫生课题和日益严重的社会问题,发掘防治AD的新靶标和新药物是当今医药领域亟待破解的难题.越来越多的研究显示,中枢肾素-血管紧张素系统(central rennin-angiotensin system,CRAS)与AD密切相关.根据相关文献报道,综述CRAS中血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)及其受体(angiotensinⅡtype l receptor,AT1R; angiotensinⅡtype 2 receptor,AT2R),血管紧张素Ⅳ(angiotensinⅣ,AngⅣ)及其受体(angiotensinⅡtype 4 receptor,AT4R)以及血管紧张素转化酶(angiotensin converting enzyme,ACE)在AD发生发展中的作用,有可能成为防治AD的新靶标,提出新型抗AD药物开发的新思路.  相似文献   

3.
The enzyme unit U, by its definition, is the amount of enzyme that catalyses the transformation of one micromole of substrate per minute under standard assay conditions. However, in practical use, it is identical with micromole or microgram per minute, which deviates from the essence of the definition as a measure of amount of substance. Such usage appears in many publications that involve enzyme kinetics and conveys obscure signification. In this article, we solved the confusion by regarding the unit U as a measure of amount of enzyme having a specified catalytic activity just like the basic SI unit mole (symbol mol) defined as the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of carbon 12. We introduced the concept of unit rate, ru, which is defined as the rate of a reaction mediated by 1 U enzyme, in calculating the enzyme units in an amount of enzyme so as to avoid the inconsistence of the expression with the definition of enzyme unit. The method can also be applied to the case of katal, the recommended SI unit of enzyme activity.  相似文献   

4.
The study was conducted to investigate fasting effects on flesh composition and antioxidant defenses of market-size Sparus macrocephalus. Two hundred fish （main initial weight 580 g） were divided into two groups （control and fasted） and reared in 6 cages. After two weeks of adaptation, group I fasted for 28 d; group II was fed normally as a control. In 3, 7, 14, 21 and 28 d, 6 fish per group were sampled for proximate flesh composition, liver antioxidant enzyme activities and malondialdehyde flesh content analyses. In fasted fish, the reduction of lipid content in muscle occurred after day 3, and, compared to controls, the content of protein decreased from day 14, the activities of liver antioxidative enzymes superoxide dismutase （SOD） and glutathione peroxidase （GPX） increased from day 3, and flesh malondialdehyde levels increased from day 21. Flesh fat reduction shows that fasting may be used as a technique to reduce flesh lipid content in Sparus macrocephalus. However, considering flesh protein loss and the subsequent oxidative stress, the fasting technique should be used with precautions.  相似文献   

5.
This paper describes an innovative method for the immobilization of acylase I, which was entrapped into the CA-CTA micropore membrane. The most suitable casting solutions proportion for immobilizing the enzyme was obtained through orthogonal experiment. Properties of the enzyme membrane were investigated and compared with those of free enzyme and blank membrane. The thermal stability and pH stability of the enzyme inside the membrane were changed by immobilization. The optimum pH was found to be 6.0, which changes 1.0 unit compared with that of free acylase I. The optimum temperature was found to be about 90 ℃, which is higher than that of free acylase I (60 ℃). Experimental results showed that immobilization had effects on the kinetic parameters of acylase I.  相似文献   

6.
Since the carbohydrate content affects pear flavor during the process of growth, it is necessary to determine the sugar components that accumulate in the fruit. We analyzed the fruit carbohydrate content, and the gene expression and activity ofacid invertase(AI), neutral invertase(NI), sucrose synthase(SS), and sucrose phosphate synthase(SPS) during the development of "Huangguan" and "Yali" pears. The results demonstrate that during development, the fruit sugar metabolism of the "Huangguan" pear follows a typical sorbitol–starch-soluble sugars middle model, whereas the "Yali" pear fruit follows a typical sorbitol–sucrose–starch-soluble sugars middle model. In the "Huangguan" pear, we found the AI and NI gene expressions, as well as AI( P 0.05) and NI( P 0.01) enzyme activities, to be positively correlated, whereas we found the NI gene expression and NI enzyme activity of "Yali" pear to be negatively correlated( P 0.01). We observed the high levels oflate-stage AI and early-stage SS during development to roughly correspond with the gene expression found in the late and early stages, respectively, suggesting their potential regulatory roles in "Huangguan" pear fruit development. Our results indicate that the primary function of SPS during the early developmental stage is to accumulate sucrose, whereas the primary function of AI is to promote hexose accumulation during the late developmental stage ofmature "Yali" pear fruit.  相似文献   

7.
Objective:To investigate the effect of enalapril on plasma homocysteine(Hcy) levels and the association of methylenetetrahydrofolate reductase(MTHFR) C677T polymorphism with the changes of Hcy levels in response to enalapril among patients with essential hypertension.Methods:A total of 130 patients with mild-to-moderate essential hypertension were enrolled and enalapril was orally administered at a dose of 10 mg/d for eight weeks.Plasma Hcy levels were measured by denaturing high-performance liquid chromatography(DHPLC) at baseline and after eight weeks of treatment.Genotyping of MTHFR C677T polymorphism was performed by TaqMan probe technique.Results:Compared with baseline,plasma Hcy levels did not change significantly after eight weeks(P=0.81).Stratified by baseline Hcy levels,a significant increase in plasma Hcy levels(P=0.02) among those with Hcy 10 μmol/L was observed,in contrast to no significant changes in plasma Hcy levels(P=0.54) among those with Hcy ≥10 μmol/L.No significant association was observed between MTHFR C677T polymorphism and changes in Hcy levels in response to enalapril.Conclusions:Enalapril may cause an increase in plasma Hcy levels among the hypertensives with low baseline Hcy levels.There was no significant association between MTHFR C677T genotypes and changes in Hcy levels in response to enalapril among subjects with essential hypertension.  相似文献   

8.
Objective:Percutaneous coronary intervention(PCI) triggers an acute inflammatory response,while sirolimus is known to have anti-inflammatory properties;the inflammatory system response to PCI after sirolimus-eluting stent placement remains unclear.The purpose of this study is to determine the changes in high sensitive C-reactive protein(hs-CRP) and apelin after PCI procedure and drug-eluting stent implantation in patients with and without reduced left ventricular systolic function.Methods:Forty-eight consecutive patients undergoing PCI at the Beijing Anzhen Hospital between July and September 2006 were recruited.Sirolimus-eluting stents were employed in all patients.Blood samples were drawn immediately before and 24 h after the procedure.Plasma hs-CRP and apelin levels were determined by enzyme immunoassay.Results:Paired t-test revealed a significant increase in both hs-CRP and apelin post-procedure(P=0.006 and P0.0001,respectively).Patients with reduced left ventricular ejection fraction(LVEF) had significantly lower baseline apelin levels compared to those with normal ventricular function [(46.8±10.8) vs.(72.0±8.4) pg/ml,P0.001].However,apelin increased to a level similar to the level of those with normal left ventricular systolic function 24 h after the PCI procedure [(86.7±11.6) vs.(85.1±6.1) pg/ml,P=0.72].Conclusions:hs-CRP and apelin levels increased after PCI and sirolimus-eluting stent implantation.Patients with impaired left ventricular systolic function had significantly lower baseline apelin levels,which increased significantly after PCI.  相似文献   

9.
Fe(Ⅲ)-2,9,16,23-tertracarboxy-phthalocyanine(Fe(Ⅲ)-taPc)was synthesized.and bonded to polystyrene(PS) with covalence by Friedel-Crafts reaction to form a new polymer(Fe(Ⅲ)-tapC-PS) (polymer(II)),UV-VIS and Infrared spectra indicated that Fe(Ⅲ)-taPc was successfully bonded to PS.A photoreceptor device of sandwich structure consisting of alternate layers of poly-mer(II)and fullerene(C60) was prepared.The experiment results show that the photoconductivity of the photoreceptor is higher than that of the single-layer film of polymer(II) or C60,because of the charge-transfer effect between the layers.  相似文献   

10.
A solution with different Cu supply levels was cultured to investigate gama-aminobutyric acid (GABA) accumulation in Elsholtzia splendens, a native Chinese Cu-tolerant and accumulating plant species. Increasing Cu from 0.25 to 500 μmol/L significantly enhanced levels of GABA and histidine (His), but considerably decreased levels of aspartate (Asp) and glutamate (Glu) in the leaves. The leaf Asp level negatively correlated with leaf Cu level, while leaf GABA level positively correlated with leaf Cu level. The leaf Glu level negatively correlated with leaf GABA level in Elsholtzia splendens. The depletion of leaf Glu may be related to the enhanced synthesis of leaf GABA under Cu stress.  相似文献   

11.
This study investigated the effect of heat treatment combined with acid and alkali on the angiotensin-Iconverting enzyme (ACE) inhibitory activity of peptides derived from bovine casein. The free amino group content, color, and cytotoxicity of the peptides were measured under different conditions. When heated at 100 °C in the pH range from 9.0 to 12.0, ACE inhibitory activity was reduced and the appearance of the peptides was significantly darkened. After thermal treatment in the presence of acid and alkali, the free amino group content of ACE inhibitory peptides decreased markedly. High temperature and prolonged heating also resulted in the loss of ACE inhibitory activity, the loss of free amino groups, and the darker coloration of bovine casein-derived peptides. However, ACE inhibitory peptides, within a concentration range of from 0.01 to 0.2 mg/ml, showed no cytotoxicity to Caco-2 and ECV-304 cell lines after heat treatment. This indicated that high temperature and alkaline heat treatment impaired the stability of bovine casein-derived ACE inhibitory peptides.  相似文献   

12.
以葛根（radix puerariae）生产葛粉后的葛渣为材料,采用乙醇回流法通过正交实验对异黄酮提取条件进行优化,同时对葛根异黄酮对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌的抑菌作用进行研究.结果表明：以乙醇作为提取溶剂,最佳提取条件为乙醇浓度95％,提取温度70℃,料液比1∶15,提取时间120 min,葛根异黄酮的得率为1.59％;葛根异黄酮对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌的生长都具有抑制作用,最低抑菌浓度分别为125 μg/mL、62.5 μg/mL、250μg/mL,最低杀菌浓度分别为250 μg/mL、125 μg/mL、500 μg/mL.  相似文献   

13.
多酚氧化酶是一种氧化还原酶,主要与植物色素的生成及其产品的色变有关,有利于水果或作物营养价值的保持．本论文以绿豆嫩叶多酚氧化酶粗提液为研究对象,采用不同条件下的磁感应强度的稳恒磁场处理,研究其对多酚氧化酶活性的影响．实验过程分别选用不同的磁感应强度以及时间处理,结果表明：在测酶活性过程中,酶与底物反映很快,1min时底物已全部反应,吸光度也不再增加．在反应初,对照组吸光度为0．8822．处理条件为1．6T15min时,磁场处理对PPO活性促进作用最明显,吸光度为1．0023．反应初始阶段完成以后,对照组酶活力为0．668U．处理条件为0．8T10min时,磁场处理对PPO活性促进作用最明显,酶活力为0．781U．  相似文献   

14.
对米渣浓缩蛋白进行复合蛋白酶和风味蛋白酶联合酶解试验,在单因素试验基础上通过正交试验优化酶解条件,所得水解液米渣蛋白提取率达到57.81%。对上述水解液进行了二次风味蛋白酶水解试验。米渣蛋白的提取率可以达到63.6%。将酶解产物冷冻干燥即得蛋白含量为84.62%的可溶性米渣蛋白粉。  相似文献   

15.
研究了不同酸性条件下豆渣对水中Cd(II)的吸附特征.结果表明:(1)在强酸(pH=2.0)、中等酸性(pH=4.0)和弱酸(pH=6.0)条件下时豆渣对Cd(II)的最大吸附率分别为55.4%、99.2%和79.4%,中等酸性条件下豆渣对水中Cd(II)的吸附率最大.(2)豆渣对Cd(II)的吸附过程遵循F方程;而L方程对弱酸条件下的吸附过程拟合较好(R2>0.99).在中等酸性和弱酸条件下,豆渣吸附Cd(II)是向有利于吸附的方向进行的,而在强酸条件下则不利于吸附.  相似文献   

16.
A newly isolated strain EL31410, producing elastase (E.C3.4.4.7) with high elastolytic activity was identified as Bacillus sp. In the medium optimization, it was found that wheat bran and soybean flour hydrosate were the best crude carbon and nitrogen source for enzyme production, respectively. Addition of corn steep flour can affect the bacterium growth and elastase production. A fractional factorial design was applied to study the main factors that affect the enzyme production, and central composite experimental design and response surface methodology were adopted to derive a statistical model for the effect of wheat bran and soybean flour hydrosate on elastase production. The experimental results showed that wheat bran had positive effect but soybean flour hydrosate had negative effect, on enzyme production. An initial concentration of 3.4%(w/v) wheat bran and 9.4%(v/v) soybean flour hydrosate were found to be optimal for enzyme production in batch culture. The time course of elastase production in the optimized medium composition was also described.  相似文献   

17.
ACE基因多态性与有氧耐力运动关系研究   总被引：4，自引：0，他引：4  
目前普遍认为ACE(血管紧张素转换酶)的水平和心血管的形态、功能密切相关。ACE基因的多态性是人耐力素质优劣的决定性因素之一。为了解运动员血管紧张素转换酶(ACE)基因插入或缺失(I/D）多态性情况，探讨ACE基因多态性与有氧耐力可能的关系，用聚合酶链反应(PCR)技术检测20例运动员和20例健康对照者的ACE基因多态性。结果位于ACE基因16内含子的L／D多态性经PCR扩增后呈三种基因型：纯合子插入型(II）、纯合子缺失型(DD)和杂合子插入或缺失型(ID)。耐力运动员组Ⅱ基因型和Ⅰ等位基因频率显著高于健康对照组。结果表明ACE基因可能在运动员的有氧耐力中起重要作用。  相似文献   

18.
ＩＮＴＲＯＤＵＣＴＩＯＮＡｎｉｎｃｒｅａｓｉｎｇｄｅｍａｎｄｆｒｏｍｃｏｎｓｕｍｅｒｓｆｏｒｈｅａｌｔｈｙａｎｄｌｏｗｃｏｓｔｍｅｄｉｃａｌｓｈａｓｌｅｄｔｏｔｈｅｄｅ ｖｅｌｏｐｍｅｎｔｏｆａｌｔｅｒｎａｔｉｖｅｍｅｄｉｃａｌｔｈｅｒａｐｙａｇｅｎｔｓｕ  相似文献   

19.
A newly isolated strain EL31410, producing elastase (E. C3. 4. 4. 7) with high elastolytic activity was identified asBacillus sp. In the medium optimization, it was found that wheat bran and soybean flour hydrosate were the best crude carbon and nitrogen source for enzyme production, respectively. Addition of corn steep flour can affect the bacterium growth and elastase production. A fractional factorial design was applied to study the main factors that affect the enzyme production, and central composite experimental design and response surface methodology were adopted to derive a statistical model for the effect of wheat bran and soybean flour hydrosate on elastase production. The experimental results showed that wheat bran had positive effect but soybean flour hydrosate had negative effect, on enzyme production. An initial concentration of 3.4% (w/v) wheat bran and 9.4% (v/v) soybean flour hydrosate were found to be optimal for enzyme production in batch culture. The time course of elastase production in the optimized medium composition was also described. Project (No. 300024) supported by the Zhejiang Provincial Natural Science Foundation of China  相似文献   

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