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.

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.

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.

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.

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.

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.

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.

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。

植物乳杆菌B发酵水牛奶产ACE抑制肽的工艺优化及其动态过程分析

采用植物乳杆菌B发酵水牛奶以提高对血管紧张素转化酶(ACE)的抑制活性。以ACE抑制率为指标,在单因素试验的基础上通过响应面法优化发酵工艺,并对发酵过程中产物的动态变化、氨基酸组成和ACE抑制活性进行分析和评价。结果表明:最佳发酵工艺为发酵温度39℃、发酵时间8 h、植物乳杆菌B菌液接种量5%(以发酵水牛奶的体积为基准),在此条件下产物的ACE抑制率为92.42%。在发酵过程中,发酵水牛奶体系中的可溶性蛋白质含量较稳定,保持在2.21~2.37 mg/g。随着发酵时间的延长,发酵水牛奶体系的pH逐渐下降,硬度、稠度、黏附性逐渐升高,发酵6 h后发酵水牛奶体系的持水力上升。氨基酸分析结果表明,水牛奶富含9种必需氨基酸和疏水性氨基酸,且随着发酵时间的延长,游离氨基酸总含量持续下降。

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。

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。

海洋生物ACE抑制肽研究进展

血管紧张素转化酶(ACE)抑制肽是一类通过抑制ACE活性实现降压作用的多肽类物质。天然来源的ACE抑制肽具有安全性高、毒副作用小、可长期服用等优点,目前已经从陆源性植物蛋白、动物蛋白中发现了多种ACE抑制肽。海洋生物是一类重要的新型生物资源,含有大量的蛋白质类物质,通过降解可得到ACE抑制肽。本文运用生物信息学检索方法,对国内外主要海洋生物ACE抑制肽的研究进行了综述,主要从材料来源、降解酶、氨基酸序列以及IC50值4个方面重点介绍海洋鱼、虾、贝、藻等来源的ACE抑制肽,比较了其可能的区别和特征,并对海洋生物ACE抑制肽应用前景进行了展望,旨在为开发和利用海洋生物蛋白,促进海洋生物活性物质的研发提供指导。

酪蛋白水解物中ACE抑制肽分离及氨基酸序列分析

以牛乳酪蛋白为底物,先经胃蛋白酶水解,再经胰蛋白酶水解,从水解物中分离获得血管紧张素转化酶（angiotensin converting enzyme,ACE）抑制肽并确定其氨基酸序列.酪蛋白的双酶水解物经超滤和葡聚糖凝胶色谱分离,分离得到3个组分,收集高ACE活性抑制效果组分Ⅱ和Ⅲ.采用离子色谱法分析水解片段的氨基酸组成,液相色谱-质谱法分析水解片段的氨基酸序列,采用固相合成法制备获得的短肽片段,用分光光度法检测ACE活-性抑制效果.结果表明,组分Ⅱ包含缬氨酸、丝氨酸、脯氨酸、亮氨酸、苯丙氨酸、谷氨酸、天冬氨酸、酪氨酸,共8种氨基酸,组分Ⅲ包含痕量的丝氨酸和酪氨酸;将组分Ⅱ和Ⅲ经液相色谱-质谱分析,获得8个片段,其中,αs2-f（56～57）∶YS、αs2-f （98～107）∶YQKFPQYLQY和κ-f （52～61）∶INNQFLPYPY具有ACE活性抑制作用,其IC50值分别为11.89、l1.75 μg/mL和421 μg/mL.

胃蛋白酶水解珠蛋白获得ACE抑制肽的工艺优化

以猪血中提取的珠蛋白为原料,水解度为指标,对胃蛋白酶水解珠蛋白的工艺条件进行优化,然后测定不同水解阶段产物对血管紧张素Ⅰ转换酶(ACE)抑制活性的影响,来筛选具有较高抑制ACE活性的生物功能活性肽。结果表明:在酶量为0.3%,初始pH值2.6,蛋白浓度0.7%,温度37℃条件下,时间为12 h时,水解度值最大,为11.85%;在其他因素不变条件下,水解时间为4 h时,水解产物对ACE抑制率达到最大值,其ACE抑制率为93.2%,水解度为9.64%。

血管紧张素转化酶抑制二肽抑制ACE作用的柔性分子对接

食源性血管紧张素转化酶(angiotensinⅠ-converting enzyme,ACE)抑制肽可有效抑制生物体内ACE活性,进而起到降压疗效,且作用温和,无副作用,是高血压治疗的理想药物,但其分子作用机制一直未有明确解释。本实验选取4个代表性食源ACE抑制二肽(Gly—Phe、Gly—Tyr、Val—Phe、Ile—Tyr)为研究对象,采用柔性分子对接的方法研究它们与ACE的相互作用模型与分子机理。分子对接结果表明:氢键、亲水、疏水、静电等作用力同时对二肽与ACE的结合有贡献,但以氢键作用为主;ACE分子中Ala354、Glu384、Arg522等氨基酸残基为二肽与其结合的重要活性位点;ACE抑制二肽中氮端氨基对其抑制活性影响显著。通过以上分子机理研究可为指导开发强活性ACE抑制肽提供理论指导。

海洋蛋白源ACE抑制肽研究进展

血管紧张素转化酶(ACE)抑制肽在血压调节中起着重要作用,食源性ACE抑制肽具有较强降血压效果,是调节血压的潜在活性成分。海洋蛋白源ACE抑制肽是食源性活性肽的重要组成部分,是未来研究的热点。本文综述了海洋蛋白源ACE抑制肽的制备、纯化、结构鉴定、体外和体内活性研究及构效关系等研究进展,同时对海洋蛋白源ACE抑制肽的研究和应用前景进行展望。

泥鳅ACE抑制肽的体外活性研究

以泥鳅蛋白为原料,酶解制备具有降血压活性的短肽,研究该肽的稳定性。在加热温度≤80℃条件下加热2h,泥鳅降血压肽(<2.5ku)的ACE抑制活性没有显著变化。当2.0≤pH≤8.0时,泥鳅降血压肽的ACE抑制活性变化不显著。冷冻干燥优于喷雾干燥。Mg2+对泥鳅降压肽的降压活性起到促进作用,而Zn2+和Mn2+抑制了肽的降压活性。葡萄糖对降压肽活性的影响程度明显大于蔗糖,随着浓度的升高,其ACE抑制活性逐渐降低,褐变程度加深;氯化钠对降压活性的影响不明显。在模拟胃肠道消化体系中,胃蛋白酶的消化显著提高了产物的降压活性;胰酶的消化降低了产物的降压活性。泥鳅多肽属于底物型ACE抑制肽。

鲢头酶解物对ACE的抑制活性

通过测定鲢Hypophthalmichthysmolitrix头酶解物对血管紧张素转化酶(ACE)的抑制率(I),确定了蛋白酶酶解鲢头制取ACE抑制肽(ACEI)的酶种及其最佳酶解工艺条件,并用SephadexG-15凝胶柱对酶解物进行分离,测定酶解物中ACE抑制肽的相对分子质量分布。结果表明:在胰蛋白酶、木瓜蛋白酶、胃蛋白酶、枯草杆菌蛋白酶和复合风味蛋白酶5种酶中,胃蛋白酶为酶解鲢头制备ACE抑制肽的理想蛋白酶;其最佳酶解工艺条件为温度37℃、pH2 0、酶解时间3h、酶的质量分数为1 4%、底物浓度w(原料)∶w(水)=1∶3,在该条件下得到的酶解物对ACE的抑制活性最强,其I=83 58%;在最佳酶解工艺条件下得到的酶解物经层析分离,在最大洗脱峰处得到的ACE抑制肽抑制活性最高,其I=86 72%,相对分子质量为1096。