A Novel Angiotensin I Converting Enzyme Inhibitory Peptide from the Milk Casein:Virtual Screening and Docking Studies

Angiotensin I converting enzyme （ACE） plays an important physiological role in the regulation of hypertension. In this study, we applied virtual screening to discover a novel angiotensin I converting enzyme inhibitory peptides from milk casein. One potential hit was identified based on docking scores, subsequently confirmed by activity studies in vitro （IC50=20.85 μmol L-1）. The proposed peptide in this study contains a unique sequence, Lys-Val-Leu-Ile-Leu-Ala. Moreover, we performed the docking studies to understand the binding mode between the enzyme and peptide hit.

Drying Technology of Angiotensin Converting Enzyme Inhibitory Peptide Derived from Bovine Casein

Drying technology of angiotensin converting enzyme （ACE） inhibitory peptides derived from bovine casein was investigated. No significance was observed on ACE inhibitory activity of products prepared by spay drying and freeze drying （P〉0.05）. Spay drying was the best drying process for practical industry production. The inlet temperature ranged from 140℃ to 160℃ and the exit temperature ranged from 70 ℃ to 90 ℃ during the spay drying process. Under the optimal conditions, scale-up of angiotensin converted enzyme inhibitory peptide from 1 L to 10 L and the experiment was successively conducted. Peptide yield was 29% and half inhibitory concentration （IC50） was 0.53 g. L^-1.

Liquid Chromatographic Assay of Peptides Activity with Inhibiting Angiotensin Converting Enzyme

A rapid, simple and interference-free method was developed to evaluate the inhibitory activity of hydrolyzed peptides from egg white protein against the angiotensin-converting enzyme. The total reaction volume was 60 μL, saving the cost. The assay was based on a HPLC separation and quantification of the synthetic substrate hippuryl-L-histidyl-L-leucine and its hydrolyzed product-hippuric acid; the separation was performed on a C18 column eluted by a mobile phase of acetonitrile/water（0.5% TFA） at a volume ratio of 25：75. At a signal to noise ratio（S/N） of 10, the detective limit of the quantitation of hippuric acid was （0.4600±0.0097） μmol/L. The standard curve shows a linear response with a slope of 49488 and a correlation coefficient of 0.9995. The assay was adequate for the study of ACE inhibition by Captopril and peptides derived from food protein, and showed a very good correlation with the previous methods.

槟榔籽提取物对血管紧张素转化酶(ACE)活性的抑制作用研究

以嫩果期槟榔籽为研究对象,采用75%乙醇浸提制得槟榔籽提取物(areca nut extract,ANE),再分别用石油醚、乙酸乙酯和正丁醇依次对总提取物进行萃取,依次得到嫩果期槟榔籽75%乙醇提取物的石油醚部位(PE-ANE)、乙酸乙酯部位(EAC-ANE)、正丁醇部位(BU-ANE)、水部位(W-ANE)的萃取部分。通过体外抑制血管紧张素转化酶(ACE)活性抑制试验测定槟榔提取物各极性部位对高血压的抑制潜力;通过酶动力学实验分析ACE抑制活性最好的极性部位对ACE活性的抑制作用类型;测定不同极性部位蛋白质、总糖及多酚的总含量,并分析其与ACE半抑制浓度(IC50)之间的相关性;最后对4种不同极性部位萃取物中的多酚组分进行初步定量。结果表明:嫩果期槟榔籽提取物各极性部位均具有一定的ACE抑制活性,其中EAC-ANE的ACE抑制活性最好。酶动力学实验表明,EAC-ANE对ACE活性的抑制作用类型为竞争与非竞争的混合型抑制。相关性分析表明,各极性部位ACE的IC50值与多酚、总糖及蛋白质含量均呈显著负相关,且与多酚含量之间具有极强相关性(r=‒0.912)。在4个极性部位中定量了儿茶素、L-表儿茶素、原花青素B2、原儿茶酸、槲皮素等多种多酚组分,且EAC-ANE中的相关多酚组分含量最高。综上所述,槟榔提取物具有一定的降血压潜力,且乙酸乙酯萃取部位最好,多酚含量与各萃取部位的ACE抑制活性具有极强的相关性,可初步推断多酚是槟榔提取物中抑制ACE活性的重要物质。

青刺果ACE抑制肽的分离纯化、结构鉴定及其体外活性评价

以具有血管紧张素转化酶(ACE)抑制活性的青刺果蛋白酶解物为研究对象,采用超滤、强阴离子交换层析分离纯化ACE抑制肽,液相色谱-串联质谱鉴定其肽序列。采用傅里叶红外光谱、酶反应抑制剂动力学、MTT试验和分子对接技术解析其二级结构特征、体外活性以及与ACE的结合机制。结果表明,分子质量<3 ku的超滤组分活性较好(IC50=0.380 mg/mL),离子交换层析后以F-a组分活性最好(IC50=0.159 mg/mL)。质谱鉴定出4条肽序列,通过生物信息学分析确定肽PGDVF为潜在的ACE抑制肽[IC50=(0.56±0.1)mmol/L]。二级结构分析表明PGDVF由α-螺旋(20.28%)、β-折叠(6.21%)、β-转角(31.55%)和无规则卷曲(41.85%)构成,其抑制模型为非竞争性抑制,肽质量浓度小于1 mg/mL时,对HepG2细胞无毒性。分子对接显示PGDVF可通过氢键、疏水作用与ACE紧密结合,从而有效抑制ACE活性。研究结果可为青刺果降压肽的开发利用提供参考。

Correlation of angiotensin converting enzyme gene polymorphism with perioperative myocardial protection under extracorporeal circulation

Objective:To observe the expression of angiotensin converting enzyme(ACE),angiotensinⅡ(AngⅡ),cardiac troponin 【cTnⅠ),creatine kinase isozymes(CK-MB) and muscle red protein(Myo) after cardiopulmonary bypass(CPB),and to investigate the association of polymorphisms in angiotensin converting enzyme genes and myocardial injury.Methods:Sixty-three patients suffered from rheumatic mitral stenosis and scheduled for mitral valve replacement with CPB, were randomly divided into three groups according polymorphisms in angiotensin converting enzyme genes:typeⅡ,type ID,type DD(each=21).Blood samples were withdrawn from artery before operation(T1),at the beginning of CPB(T2),30 min after CPB(T3),(T4) at the end of CPB(T5), 2 h after CPB(T6),6 h after CPB(17) to measure the expression of ACE,AngⅡ,cTnⅠ,CK-MB, Myo.Results:The level of ACE during and after CPB were significantly higher than those before CPB(P【0.05).As extension of CPB time,the expression of ACE was increased.The level of cTnⅠ, CK-MB,Myo after CPB were significantly higher than those before CPB(P【0.05).The level of cTnⅠ,CK-MB and Myo were highest at T7,T6 and T5 and T7,respectively.The level of ACE,AngⅡ,cTnⅠin patients with DD genotype was significantly higher than the ID andⅡgenotype(P【 0.05).Besides,the level of ACE,AngⅡin patients with ID genotype was significantly higher than the II(P【 0.05).Conclusions:There is certain correlation between CPB perioperative midterm ACE and cTnⅠ,Myo,CK-MB.ACE DD genotype is a susceptibility gene of the CPB perioperative myocardial injury.

料酒糟源新ACE抑制肽的分离纯化、活性评价与结构解析

传统料酒以大米为原料发酵生产,料酒糟作为料酒酿造的主要产物,其中含有大量的营养物质。本文以料酒糟作为原料,通过一次醇沉分离,一次制备液相色谱分离和一次分析液相分离后,得到两个高活性ACE抑制肽单体F1和F2。在相同浓度下,单体F1、F2的ACE抑制率分别高于市售降压肽产品约17%和14%。后续,利用LTQ Orbitrap Velos Pro质谱仪对两个单体的结构进行解析,结合Uniprot数据库搜索,鉴定出了多肽的序列分别为F1:LIIPQH,F2:IFSGFNNELLS。其中,F1为已报道过的降压肽序列,而F2为本实验首次报道的降压肽序列。研究为酒糟的高值化加工利用提供了理论依据,也为食源性降压肽提供了新证据。

Microwave-assisted Solid-phase Synthesis, Biological Evaluation and Molecular Docking of Angiotensin I-converting Enzyme Inhibitors

Short peptides based on the tripeptides, Leu-Arg-Pro and Leu-Lys-Pro, were synthesized by microwave assisted solid-phase synthesis method, in order to make a search for potential inhibitors for angiotensin I-converting enzyme（ACE） with minimum side effects in the treatment of hypertension. One peptide with the sequence Leu-Arg-Pro-Phe-Phe shows the strongest inhibition towards ACE with an IC50 value of 0.26 μmol/L in vitro. The study of structure-activity relationship shows that the introduction of a bulky group into the N-terminal of this series of inhibitors may enlarge steric hindrance, resulting in the poor inhibitory activity towards ACE. The inhibitory activity decreased in turn when L-Pro, D-Pro or Ac6c was at the C-terminal respectively. The binding interaction between each of these inhibitors and testicular ACE（tACE） was performed by molecular docking. The results suggest that Leu-Arg-Pro-Phe-Phe mainly occupied the S1 subsite of tACE, and made contact with tACE via seven H-bonds. It appeared that the site on the peptide that bound with tACE was influenced by the configuration of the amino acid, L or D-form, at the C-terminal of the peptide.

Study of angiotensin converting enzyme and genotype among Egyptian preeclampsia patients

Preeclampsia is a frequent disorder with reported incidence in pregnancies. In Egypt, it complicates 6%-8% of pregnancies and reaches 15% in referral centers. The renin-angiotensin system activation during the early stages of Preeclampsia proved to be a direct cause. Women carrying the D allele of the ACE-I/D polymorphism have higher measures of uterine artery resistance, which is a marker for development of intrauterine growth retardation and preeclampsia. The maternal syndrome of preeclampsia (PE) during the latter half of pregnancy is believed to result from impaired placentation in early gestation and a failure to develop low resistance uteroplacental circulation. Aim: The aim of this study was to evaluate the association with angiotensin converting enzyme gene polymorphism and changes in its enzyme serum level in preeclamptic patients compared to non preeclamptic control group together with studying the changes in umbilical artery and uterine artery Doppler. Subjects: The study was conducted on 180 pregnant women allocated into two groups having the same inclusion and exclusion criteria except for hypertension and proteinuria;each group comprised of 90 pregnant women with matched age. Methods: Doppler study of umbilical and uterine arteries and the detection of Angiotensin converting gene polymorphism by PCR with Estimation of serum ACE in serum by ELISA technique. Results: The distribution of the ACE-I/D genotypes and allelic frequencies in the present study of polymorphism was 37.8% for the DD, 48.9% for the ID, 13.3% for the II in preeclampsia group while it was 33.3% for the DD, 46.7% for the ID, and 20% for the II in the control group. There was no significant difference between cases and controls regarding the cumulative D effect. Conclusions: No existence of a relation between preeclampsia and ACE gene polymorphism considering different modes of inheritance whether is dominance or recessiveness. No effect of ACE gene polymorphism is on ACE serum level. Positive correlation between ACE gene polymorphism and the uterine artery Doppler changes gives strong evidence that ACE gene may have a role in the histopathological changes taking place in these vessels, therefore affecting maternal prognosis. It is unclear to explain this mismatched ACE genetic influence on the incidence of preeclampsia, but the multifactorial pathogenesis of the development and complication in preeclampsia and also physician’s intervention may contribute to the pregnancy outcome. Recommendations: International collaborations, particularly among countries with a high incidence of preeclampsia, may help to include participants with different cultural and genetic backgrounds, which can provide further insight into the etiology of the disease both genetic and environmental.

棉籽蛋白ACE抑制肽的酶法制备及其体外稳定性研究

食源性血管紧张素转化酶(angiotensin-I-converting enzyme,ACE)抑制肽因安全、无副作用、易吸收等优点,对防治高血压、提高居民健康水平具有重要作用。利用碱性蛋白酶、复合蛋白酶、风味蛋白酶、木瓜蛋白酶和菠萝蛋白酶水解棉籽蛋白制备ACE抑制肽,通过单因素实验优化水解条件,分离纯化水解物并鉴定其活性肽段组成,评价水解物的体外消化吸收稳定性。结果表明,棉籽蛋白经复合蛋白酶(1500 U/g)在pH值为8.0和55℃下水解5 h,蛋白回收率为39.8%,ACE抑制率可达93.7%。棉籽蛋白复合蛋白酶水解物经分离得到5个组分,其中组分4(F4)的ACE抑制活性最高(IC_(50)=220.1μg/mL)。从该组分中发现3条新型ACE抑制肽:VFNNNPQE、LLSQTPRY和VFPGCPET,其中LLSQTPRY的活性最高(IC_(50)=105.2μmol/L)。经人工胃肠液消化和Caco-2细胞单层膜吸收后,棉籽蛋白复合蛋白酶水解物仍具有一定ACE抑制活性,分别为53.8%和20.5%。研究结果表明,棉籽蛋白的复合蛋白酶水解物有望作为一种功能性食品配料,用于开发降压食品。

辣木籽ACE抑制肽的分离纯化、结构鉴定及其体外活性评价

采用超滤、离子交换层析分离辣木籽蛋白酶解产物,以血管紧张素转换酶(angiotensin-converting enzyme,ACE)抑制率为评价指标,筛选具有较高降压活性的肽组分,并通过高效液相色谱-串联质谱鉴定其肽序列,结合生物信息学和分子对接技术筛选出潜在的ACE抑制肽,进一步利用傅里叶变换红外光谱、酶反应抑制剂动力学和四甲基偶氮唑蓝法实验解析其二级结构特征及体外活性。结果表明:分离得到的F-b肽组分具有较好的降压效果,共鉴定出11条肽序列,进一步筛选出肽QGPRPQ为潜在的ACE抑制肽(IC_(50)=(1.15±0.3)mmol/L),分子对接表明QGPRPQ可以与ACE以氢键、疏水作用更好地结合;二级结构分析表明QGPRPQ由22.8%α-螺旋、33.3%β-折叠和43.9%β-转角构成;QGPRPQ的抑制模型为混合型抑制,且质量浓度低于0.01 mg/mL时对HepG2细胞无毒性作用。该研究可为辣木籽蛋白源降压肽的开发利用提供一定的理论参考。

青稞源ACE抑制糖肽结构及其稳定性研究

为制备一种血管紧张素转换酶(ACE)抑制糖肽并研究其结构及稳定性,选用嗜热链球菌和米根霉混合发酵青稞,单因素和响应面法优化发酵条件,凝胶色谱、反相高效液相色谱(RP-HPLC)分离纯化ACE抑制糖肽,红外光谱和β-消除法分析其结构,考察ACE抑制糖肽物理化学和体外胃肠模拟消化稳定性。料液比1.0∶15.5 g/mL,接菌量2.4%,嗜热链球菌∶米根霉1∶1,发酵6.4 d,ACE抑制率达65.79%;Sephadex G-15分离获得的A_(2)组分ACE抑制活性最高(IC_(50)=2.0 mg/mL);RP-HPLC分离得到的组分F5纯度达95.17%;ACE抑制糖肽具有糖和多肽的典型结构,糖苷键为O-糖肽键;高温、强碱、高NaCl含量及体外胃肠模拟消化显著影响ACE抑制糖肽活性。

源于皱纹盘鲍裙边胶原蛋白ACE抑制肽的制备

为了提高皱纹盘鲍(Haliotis discus hannai)裙边的利用率,以其为原料纯化胶原蛋白,并通过胰蛋白酶和胃蛋白酶共酶解制备血管紧张素转换酶(angiotensin I-converting enzyme,ACE)抑制肽。酶解液经超滤、Superdex^(TM) peptide 10/300 GL凝胶柱和高效液相色谱分离纯化,获得了3条来源于皱纹盘鲍胶原蛋白的肽段SGEVGQ、QRGPAGAQGPQ和GPPGPAGAR。其中结合能力最强的肽为GPPGPAGAR,对ACE的IC_(50)值为177.1μmol/L,分子对接结果显示其主要作用于ACE的S_(1)活性口袋,抑制模式与赖诺普利类似,并且经模拟胃肠液消化后仍能发挥较强的ACE抑制作用。本研究通过酶解皱纹盘鲍裙边胶原蛋白制备ACE抑制肽,为鲍鱼裙边的精深加工和ACE抑制肽的开发提供了参考。

亚临界水制备芝麻ACE抑制肽的分离纯化、构效、分子对接

以亚临界水降解高温芝麻饼粕蛋白水解液为研究对象,通过纳滤、超滤及液相层析系统对水解液中血管紧张素转化酶(angiotension converting enzyme,ACE)抑制肽进行分离纯化,并通过液相色谱-质谱联用仪进行结构鉴定,合成相应寡肽验证ACE抑制活性。预测寡肽的吸收代谢特性,建立三维定量构效关系(three dimensional quantitative structure-activity relationship,3D-QSAR)模型,并进行分子对接分析。结果显示:分子质量<3 kDa组分具有最强的ACE抑制作用,进一步纯化后从峰1组分中共鉴定到9个ACE抑制肽,这些肽不会干涉人体正常的生理活动。基于比较分子场分析法成功建立LFRAF的3D-QSAR模型。ACE抑制肽的C端处带正电荷氨基酸残基与侧链处引入大基团能够提高ACE抑制能力。LFRAF通过占据ACE的S2、S1′活性口袋,并与Zn2+结合从而抑制ACE活性。该结果表明采用亚临界水技术降解高温芝麻粕中蛋白制备ACE抑制肽可行。

藜麦源ACE抑制糖肽制备、结构表征及体外稳定性研究

利用毛霉和米根霉混合发酵藜麦制备藜麦源血管紧张素转化酶(angiotensin-I converting enzyme,ACE)抑制糖肽。通过单因素实验和响应面试验优化发酵工艺条件,发酵液经真空浓缩、醇沉、葡聚糖凝胶G-15和反相高效液相色谱分离纯化,利用傅里叶红外光谱法判断官能团构成,β-消除法判断糖肽键链接方式,并分析温度、p H、金属离子以及体外模拟消化对活性的影响。结果表明:在料液比1:18 g/m L、毛霉与米根霉接种量比1:1、总接种量2.8%(φ)、发酵时间8.7 d时,得到ACE抑制率为64.22%±4.57%的藜麦发酵液,分离纯化后获得单一组分F_(3)b。利用傅里叶红外光谱检测,发现F_(3)b具有多肽和多糖的特征吸收,β-消除法确定其存在O-糖肽键。体外稳定性研究结果表明,温度(25~55°C)对F3b活性影响较小,100℃处理后ACE抑制率为25℃时的86.23%±3.47%;不同p H条件(pH2~12)对其活性无显著影响(P>0.05);在Zn2+和Fe3+浓度为4 mmol/L时,ACE抑制率分别为对照的109.91%±8.12%和117.43%±6.78%,增强其活性;相同浓度的K+和Ca2+减弱其活性,ACE抑制率分别为对照的78.94%±2.18%和85.31%±4.99%;模拟胃肠消化过程中,F3b活性略有降低,ACE抑制率为对照的70.00%±3.30%。该研究丰富了ACE抑制肽的种类,为藜麦资源高值化利用提供理论和数据技术参考。

多棘海盘车多肽的制备及其抑制ACE活性研究

采用酶解法制备多棘海盘车多肽,选取胃蛋白酶、木瓜蛋白酶和碱性蛋白酶分别酶解多棘海盘车的水溶性蛋白,获得多肽样品PE-P、PA-P和AP-P。选取胰蛋白酶水解多棘海盘车的水溶性蛋白后再用质量分数为30%,50%,80%的硫酸铵溶液分别沉淀出不同分子量范围的多肽样品P-1,P-2和P-3。然后采用HPLC法分别测定上述多肽的血管紧张素转换酶(ACE)抑制活性。结果表明,PE-P,PA-P和AP-P均具有一定的抑制ACE活性,其中AP-P的抑制活性最好,PA-P次之,PE-P最差,它们的IC50值分别为0.6827,0.5526,0.3328 mg/mL。通过对P-1,P-2和P-3分析结果可知,分子量越小的多肽对ACE的抑制活性越显著。

Pharmacophore-based structure optimization of angiotensin converting enzyme inhibitory peptide

Chemical feature based pharmacophore models were generated for an angiotensin converting enzyme(ACE) inhibitory peptide using the Discovery Studio 2.0 pharmacophore modeling approach. The pharmacophore hypothesis selected has five features(one negative ionizable region,one hydrogen bond donor,one hydrogen bond acceptor and two hydrophobic functional groups). Additionally,ACE inhibitory hexapeptide previously obtained from silkworm pupae protein was optimized to target the ACE based on the selected pharmacophore. The results suggest that tri-peptide(thr-val-phe) may be structural determinant of ACE activity. Docking studies further provided confidence for the validity of the selected pharmacophore model to perform structure optimization of the ACE inhibitory peptide.

Inhibitory mechanism of angiotensin-converting enzyme inhibitory peptides from black tea

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.

ACE抑制肽的生理功能和研究进展

血管紧张素转化酶(ACE)在人体血压调节方面起着重要的生理作用。近年来天然食品来源的ACE抑制肽已成为生物活性肽研究领域的热点。ACE抑制肽通过抑制ACE活性起降血压作用。文章综述了ACE抑制肽的作用机制、结构特点、评价方法和研究进展。

红毛藻血管紧张素转化酶抑制肽的筛选及其稳定性评价

本实验以红毛藻为原料,利用酶解法及超滤分级制备获得不同分子质量的肽组分,经高效液相色谱法测定体外血管紧张素转化酶(angiotensin-converting enzyme,ACE)抑制活性发现F2组分(800~2000 Da)的ACE抑制率最高;采用液相色谱-串联质谱技术和PEAKS Studio软件的de novo从头测序对F2组分进行氨基酸序列鉴定,并结合分子对接筛选出与ACE稳定结合的6个ACE抑制肽。利用固相合成法制备预测肽并经体外ACE抑制活性验证,发现L1(LVLLFLFGE)的ACE抑制活性最高,半抑制浓度(half maximal inhibitory concentration,IC_(50))为14.22μg/mL。分子对接结果表明,L1对ACE的抑制主要归因于其能够与ACE的活性口袋形成氢键相互作用。最后,探讨温度、pH值、金属离子、光照类型和模拟胃肠道酶系消化对L1稳定性的影响,结果表明L1具有较好的热稳定性和离子强度稳定性,pH>2时抑制活性逐步减弱,紫外光处理会影响其抑制活性,体外模拟胃肠液处理后L1的ACE抑制率虽然显著降低,但仍具有较高ACE抑制活性。