Converting Enzyme Inhibitory Peptides Research Articles

Production of the angiotensin I converting enzyme inhibitory peptides and isolation of four novel peptides from jellyfish (Rhopilema esculentum) protein hydrolysate.

Angiotensin I converting enzyme (ACE) plays an important role in regulating blood pressure in the human body. ACE inhibitory peptides derived from food proteins could exert antihypertensive effects without side effects. Jellyfish (Rhopilema esculentum) is an important fishery resource suitable for production of ACE inhibitory peptides. The objective of this study was to optimize the hydrolysis conditions for production of protein hydrolysate from R. esculentum (RPH) with ACE inhibitory activity, and to isolate and identify the ACE inhibitory peptides from RPH. Rhopilema esculentum protein was hydrolyzed with Compound proteinase AQ to produce protein hydrolysate with ACE inhibitory activity, and the hydrolysis conditions were optimized using response surface methodology. The optimum parameters for producing peptides with the highest ACE inhibitory activity were as follows: hydrolysis time 3.90 h, hydrolysis temperature 58 °C, enzyme:substrate ratio 2.8% and pH 7.60. Under these conditions, the ACE inhibitory rate reached 32.21%. In addition, four novel ACE inhibitory peptides were isolated, and their amino acids sequences were identified as Val-Gly-Pro-Tyr, Phe-Thr-Tyr-Val-Pro-Gly, Phe-Thr-Tyr-Val-Pro-Gly-Ala and Phe-Gln-Ala-Val-Trp-Ala-Gly, respectively. The IC50 value of the purified peptides for ACE inhibitory activity was 8.40, 23.42, 21.15 and 19.11 µmol L(-1) . These results indicate that the protein hydrolysate prepared from R. esculentum might be a commercial competitive source of ACE inhibitory ingredients to be used in functional foods. © 2015 Society of Chemical Industry.

Purification and characterization of angiotensin converting enzyme-inhibitory peptides derived from Stichopus horrens: Stability study against the ACE and inhibition kinetics

Stichopus horrens is the most popular species of sea cucumber due to strong beliefs of its numerous medicinal properties. In this study, ACE-inhibitory peptides of S. horrens generated through enzymatic hydrolysis using Alcalase were isolated. Three peptides EVSQGRP, CRQNTLGHNTQTSIAQ and VSRHFASYAN were found to exhibit high inhibition potency with IC50 values of 0.05, 0.08 and 0.21 mM, respectively. It was found that the EVSQGRP, VSRHFASYAN and SAAVGSP exhibiting mixed inhibition patterns were susceptible to degradation by ACE as well, suggesting that the mixed-mode inhibition could be a result of new generated peptide fragments while CRQNTLGHNTQTSIAQ inhibited ACE in a non-competitive manner. In-vivo ACE inhibition studies showed that 400 mg/kg of Alcalase-generated proteolysate stabilized the blood pressure in normotensive rats. These results suggest that the hydrolysed protein components of S. horrens possess bioactive peptides that can be exploited as functional food ingredients against hypertension.

Production of angiotensin I converting enzyme inhibitory (ACE-I) peptides during milk fermentation and their role in reducing hypertension

ABSTRACTFermented milk is a potential source of various biologically active peptides with specific health benefits. Angiotensin converting enzyme inhibitory (ACE-I) peptides are one of the most studied bioactive peptides produced during milk fermentation. The presence of these peptides is reported in various fermented milk products such as, yoghurt, cheese, sour milk, etc., which are also available as commercial products. Many of the ACE-I peptides formed during milk fermentation are resistant to gastrointestinal digestion and inhibit angiotensin converting enzyme (ACE) in the rennin angiotension system (RAS). There are various factors, which affect the formation ACE-I peptides and their ability to reach the target tissue in active form, which includes type of starters (lactic acid bacteria (LAB), yeast, etc.), substrate composition (casein type, whey protein, etc.), composition of ACE-I peptide, pre and post-fermentation treatments, and its stability during gastrointestinal digestion. The antihypertensive effect of fermented milk products has also been proved by various in vitro and in vivo (animal and human trials) experiments. This paper reviews the literature on fermented milk products as a source of ACE-I peptides and various factors affecting the production and activity of ACE-I peptides.

Data in support of optimized production of angiotensin-I converting enzyme inhibitory peptides derived from proteolytic hydrolysate of bitter melon seed proteins.

VY-7 has been demonstrated as a potent ACE inhibitory peptide in the previous study [1]. In this article, we provide accompanying data about the identification of bitter melon seed proteins (BMSPs), and quantitative analysis and optimized production of VY-7 in BMSPs hydrolysate.

Screening, discovery, and characterization of angiotensin-I converting enzyme inhibitory peptides derived from proteolytic hydrolysate of bitter melon seed proteins

In this study, new angiotensin-I converting enzyme (ACE) inhibitory peptides were comprehensively identified from a thermolysin digest of bitter melon (Momordica charantia) seed proteins. The hydrolysate was fractionated by reversed-phase high performance liquid chromatography (RP-HPLC), and the inhibitory activities of the resulting fractions were evaluated using ACE inhibitory assay. Two novel ACE inhibitory peptides (VY-7 and VG-8) were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and database-assisted peptide sequencing. VY-7 and VG-8 were derived from momordin A and MAP30, respectively, and their IC50 values were as low as 8.64±0.60 and 13.30±0.62μM, respectively. Lineweaver–Burk plots further indicated that VY-7, which showed the best IC50 value, acts as a competitive inhibitor. Notably, the content of VY-7 in crude thermolysin digest was determined to be as high as 14.89±0.88μg/mg using LC-MS/MS quantification. In the spontaneously hypertensive rat (SHR) model, oral administration of VY-7 at 2mg/kg body weight significantly decreased the systolic blood pressure. The interaction between VY-7 and ACE was examined using molecular docking calculations and the results suggested that certain residues of VY-7 can fit perfectly into the S1, S1’ and S2’ regions of the binding pocket of ACE. Biological significanceOne of the most common supportive therapies for treating hypertension is the use of synthetic drugs to inhibit ACE activity. Synthetic ACE inhibitors possess good antihypertensive effects, but come with accompanying side effects. Therefore, food-derived ACE inhibitory peptides are regarded as safer alternatives and are attracting much attention for hypertension treatment. In this study, we comprehensively identified peptides derived from bitter melon (Momordica charantia) seed proteins (BMSPs) using a shotgun proteomics approach. Based on results from an in vitro ACE inhibitory assay, two peptides (VY-7 and VG-8) derived from momordin A and MAP30 proteins, respectively, showed good ACE inhibitory activities. For VY-7, which showed the best IC50 value (8.64±0.60μM), the inhibition type was determined to be competitive inhibition, as found using a Lineweaver–Burk plot. The novel ACE inhibitory peptide VY-7 (at 2mg/kg body weight) as well as the crude hydrolysate of BMSPs (at 10mg/kg body weight) showed significant and moderate antihypertensive effects, respectively, in an animal model of hypertension, spontaneously hypertensive rats (SHRs). The present work demonstrated the screening of ACE inhibitory peptides from BMSPs and, as far as we know, VY-7 is the first well-characterized antihypertensive peptide derived from bitter melon seeds.

Białka pstrąga tęczowego jako potencjalne źródło biologicznie aktywnych peptydów

1. Lee JK, Jeon JK, Byun HG. Antihypertensive effect of novel angiotensin I converting enzyme inhibitory peptide from chum salmon (Oncorhynchus keta) skin in spontaneously hypertensive rats. J Funct Foods. 2014; 7: 381–389. CrossRef Google Scholar

Hybrid in Silico/in Vitro Approach for the Identification of Angiotensin I Converting Enzyme Inhibitory Peptides from Parma Dry-Cured Ham.

The bioactivity assessment of foodborne peptides is currently a research area of great relevance, and, in particular, several studies are devoted to the antihypertensive effects through the inhibition of angiotensin I converting enzyme (ACE). In the present work, a straightforward workflow to identify inhibitory peptides from food matrices is proposed, which involves a hybrid in vitro/in silico tandem approach. Parma dry-cured ham was chosen as case study. In particular, the advantage of using the hybrid approach to identify active sequences (in comparison to the experimental trials alone) has been pointed out. Specifically, fractions obtained by in vitro gastrointestinal digestion of ham samples of 18 and 24 months of aging have been assessed for ACE inhibition. At the same time, the released peptidomic profiles, which cannot be entirely evaluated by using in vitro assays, have been screened for the inhibition by using an in silico model. Then, to identify novel inhibitory sequences, a series of strong candidates have been synthesized and assessed for their inhibitory activity through in vitro assay. On the one hand, the use of computational simulations appeared to be an effective strategy to find active sequences, as confirmed by in vitro analysis. On the other hand, strong inhibitory sequences were identified for the first time in Parma dry-cured ham (e.g., LGL and SFVTT with IC50 values of 145 and 395 μM, respectively), which is a product of international dietary and economic relevance. Therefore, these findings demonstrate the usefulness of in silico methodologies coupled to in vitro tests for the identification of potentially bioactive peptides, and they give an important contribution to the study of the overall nutritional value of Parma ham.

In silico investigation of action mechanism of four novel angiotensin-I converting enzyme inhibitory peptides modified with Trp

To potentiate activities of angiotensin-I converting enzyme (ACE) inhibitory peptides VK, YA, KY and TAY from oyster hydrolysate, four novel tripeptides VKW, YAW, KYW and TAW were designed by modification with Trp at the C-terminus. The tripeptides were synthesized, and their 50% ACE inhibitory concentrations (IC50) were measured to be 0.020, 0.49, 0.43 and 0.63 µM, respectively. Their activities increased 27–1450 times compared to their corresponding original peptides. All peptides did not show toxicity on the Chang cell. Molecular docking and molecular dynamics simulation showed that modification with Trp can enhance the stability of ACE/derived peptide complexes by increasing binding affinity and interaction sites with important amino acid residues. Interactions between peptides with amino acid residues of ACE GLN281, ALA354, GLU411, PHE457 and LYS511 played an important role in activity improvement of derived peptides. Modification with Trp at the C-terminus was an effective way for designing novel ACE inhibitory peptides.

Egg ovotransferrin-derived ACE inhibitory peptide IRW increases ACE2 but decreases proinflammatory genes expression in mesenteric artery of spontaneously hypertensive rats.

ScopeEgg ovotransferrin‐derived angiotensin converting enzyme (ACE) inhibitory peptide IRW was previously shown to reduce blood pressure in spontaneously hypertensive rats through reduced vascular inflammation and increased nitric oxide‐mediated vasorelaxation. The main objective of the present study was to investigate the molecular mechanism of this peptide through transcriptome analysis by RNAseq technique.Methods and resultsTotal RNA was extracted from kidney and mesenteric arteries; the RNAseq libraries (from untreated and IRW‐treated groups) were constructed and subjected to sequence using HiSeq 2000 system (Illumina) system. A total of 12 764 and 13 352 genes were detected in kidney and mesenteric arteries, respectively. The differentially expressed (DE) genes between untreated and IRW‐treated groups were identified and the functional analysis through ingenuity pathway analysis revealed a greater role of DE genes identified from mesenteric arteries than that of kidney in modulating various cardiovascular functions. Subsequent qPCR analysis further confirmed that IRW significantly increased the expression of ACE‐2, ABCB‐1, IRF‐8, and CDH‐1 while significantly decreased the expression ICAM‐1 and VCAM‐1 in mesenteric arteries.ConclusionOur research showed for the first time that ACE inhibitory peptide IRW could contribute to its antihypertensive activity through increased ACE2 and decreased proinflammatory genes expression.

Separation of angiotensin I‐converting enzyme inhibitory peptides from bovine connective tissue and their stability towards temperature, pH and digestive enzymes

SummaryBovine collagen was isolated from connective tissue, a by‐product in the meat processing industry and characterised by SDS‐PAGE. Alcalase and papain were employed to generate collagen hydrolysates with different degree of hydrolysis (DH). In vitro angiotensin I‐converting enzyme (ACE) inhibitory activities were evaluated and the two most potent hydrolysates from each enzyme were separated by two‐step purification. Both alcalase‐catalysed and papain‐catalysed hydrolysates exhibited strong ACE inhibitory capacities with IC50 values of 0.17 and 0.35 mg mL−1, respectively. Purification by ion‐exchange chromatography and gel filtration chromatography revealed higher ACE inhibitory activities in one fraction from each enzyme with IC50 values of 3.95 and 7.29 μg mL−1. These peptide fractions were characterised as 6‐12 amino acid residues by MALDI‐TOF/MS. The peptides retained their activity (>90%) after exposure to processing temperature and pH and in vitro simulated gastrointestinal digestion. The present results demonstrated that collagen peptides can be utilised for developing high value‐added ingredients, for example ACE inhibitory peptides.

Purification and molecular docking study of a novel angiotensin-I converting enzyme (ACE) inhibitory peptide from alcalase hydrolysate of ultrasonic-pretreated silkworm pupa (Bombyx mori) protein

Silkworm pupa (Bombyx mori) protein (SPP) was treated by ultrasound, and then was hydrolyzed using alcalase. The hydrolysate with the highest ACE inhibitory activity was obtained at hydrolysis of 50min when SPP was treated at power of 410W/100ml for 32min. The hydrolysate was fractionated by ultrafiltration, and peptide with the highest ACE inhibitory activity was purified from <5kDa fraction using gel filtration and RP-HPLC. A novel peptide was identified as Lys-His-Val (IC50=12.82μM), and it was stable against the gastrointestinal proteases. The molecular docking study revealed that ACE inhibitory activity of the tripeptide was mainly attributed to the hydrogen bond interactions and Zn(II) interaction between the tripeptide and ACE. These results suggest that the tripeptide is a potential natural ACE inhibitor that can be used as drug or functional food ingredient.

Rapid purification and characterization of angiotensin converting enzyme inhibitory peptides from lizard fish protein hydrolysates with magnetic affinity separation

In this study, angiotensin converting enzyme (ACE) inhibitory peptides from lizard fish protein hydrolysate with neutral protease were purified through magnetic affinity separation. Magnetic agarose microsphere was prepared by reverse-phase microemulsion method, and its surface was modified with epoxy groups to immobilize ACE as a magnetic affinity medium (MAM-ACE) and then mixed with lizard fish ultrafiltration hydrolysate (<5kDa). The MAM-ACE was recovered by a magnet. The bound peptides were released by 1M NaCl and further purified by reverse-phase high-performance liquid chromatography. The amino acid sequence of the peptide with the highest ACE inhibitory activity was identified as Gly-Met-Lys-Cys-Ala-Phe, and its IC50 was 45.7±1.1μM. The result indicates that MAM-ACE is a faster and more efficient method for purifying micro-bioactive peptides from food protein complex mixtures compared with ion exchange and gel chromatography.

High-level expression of angiotensin converting enzyme inhibitory peptide Tuna AI as tandem multimer in Escherichia coli BL21 (DE3)

Food-derived angiotensin converting enzyme inhibitory peptides (ACEIP) show a great promise for prevention and treatment of hypertension. Tuna muscle derived peptide, Tuna AI (PTHIKWGD), is a potent ACEIP with high activity and stability. To improve the expression level of Tuna AI in Escherichia coli, multimer genes of Tuna AI were assembled and expressed as fusion proteins by constructing the vectors of pET30-4nTunaAI (n=1, 2, 4 and 8). The results showed the multimer genes were successfully expressed in the constructed system, and their expression level improved significantly with increasing repeat degree. The E. coli harboring pET30-32TunaAI was selected for production of peptide based on its highest expression level and its fusion protein was suit for urea-washing purification. The peptide monomer was released from the fusion protein by formic acid cleavage, and successively purified by membrane filtration, cation exchange chromatography and size exclusion chromatography, with a final yield of 218.9mg/L. The purified monomeric peptide was confirmed by mass spectrometry analysis, N-terminal sequencing, and activity measurement. This peptide resulted in a significant decrease of systolic blood pressure by 36.5mmHg in rats at 4h. These results suggest our strategy is an economic solution for the mass production of antihypertensive peptides.

Further evidence that a new type of Japanese pickles reduce the blood pressure of spontaneously hypertensive rats.

A new type of pickles (nukazuke) that contain GABA and angiotensin converting enzyme-inhibitory peptides and that reduce blood pressure of rats was studied further. Seven kinds of nukazuke forcefully administrated orally for one day reduced temporarily the blood pressure of spontaneously hypertensive rats. In addition, a fermented shougoin daikon administrated freely for 4 weeks did not increase the blood pressure of the rats, but suppressed it throughout the experiment. Taken together with previous data (Oda et al., Biosci. Biotechnol. Biochem., 2014) it was concluded that the nukazuke could reduce the blood pressure of spontaneously hypertensive rats. Thus, the newly developed functional pickles appear to be beneficial for pickles business.

Extraction of antioxidant and ACE inhibitory peptides from Thai traditional fermented shrimp pastes

Antioxidant and angiotensin converting enzyme (ACE) inhibitory peptides were extracted and isolated from two different types of Thai traditional fermented shrimp pastes, Kapi Ta Dam (Kp-B6) and Kapi Ta Deang (Kp-R6). Compounds with masses less than 500Da were found to be predominantly presented in both extracts. Following fractionation with sequential anion exchange chromatography and solid phase extraction (C18 matrix), three dipeptides were identified. Ser-Val and Ile-Phe were shown to exhibit ACE inhibitory activity with IC50 values of 60.68±1.06 and 70.03±1.45μM, respectively. Trp-Pro was shown to have high 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity (EC50 17.52±0.46μM). These results indicate that Thai traditional fermented shrimp pastes are potential sources of bioactive peptides possessing ACE inhibitory and antioxidant activities.

Generation and identification of angiotensin converting enzyme (ACE) inhibitory peptides from a brewers’ spent grain protein isolate

An alkaline extracted brewers’ spent grain protein-enriched isolate (BSG-PI) was hydrolysed using Alcalase, Corolase PP, Flavourzyme and Promod 144MG, yielding Alc hydrolysate (H), CorH, FlavH and ProH, respectively. The degree of hydrolysis (DH) of the protein hydrolysates varied from 4.45% for ProH to 16.4% for CorH. The in vitro ACE inhibitory activity of the BSG-PI increased significantly following 15min incubations with Alcalase, Corolase PP and Flavourzyme. The 5kDa ultrafiltration permeates of FlavH and CorH resulted in lower ACE IC50 values than their respective hydrolysates. The bioactivity of the BSG-PI hydrolysates was retained after simulated gastrointestinal digestion (SGID) while SGID also resulted in the release of ACE inhibitory peptides from the BSG-PI and ProH. UPLC–MS/MS analysis resulted in the identification of 34 peptides. Of 12 synthesised peptides, IVY and ILDL were the most potent, having ACE IC50 values at 80.4±11.9 and 96.4±8.36μM, respectively.

Angiotensin-I converting enzyme inhibitory peptides from antihypertensive skate (Okamejei kenojei) skin gelatin hydrolysate in spontaneously hypertensive rats

The aim of this study was to investigate antihypertensive effect of bioactive peptides from skate (Okamejei kenojei) skin gelatin. The Alcalase/protease gelatin hydrolysate below 1kDa (SAP) exhibited the highest angiotensin-I converting enzyme (ACE) inhibition compared to other hydrolysates. SAP can decrease systolic blood pressure significantly in spontaneously hypertensive rats. SAP inhibited vasoconstriction via PPAR-γ expression, activation and phosphorylation of eNOS in lungs. Moreover, the expression levels of endothelin-1, RhoA, α-smooth muscle actin, cleaved caspase 3 and MAPK were decreased by SAP in lungs. Vascularity, muscularization and cellular proliferation in lungs were detected by immunohistochemical staining. Finally, two purified peptides (LGPLGHQ, 720Da and MVGSAPGVL, 829Da) showed potent ACE inhibition with IC50 values of 4.22 and 3.09μM, respectively. These results indicate that bioactive peptides isolated from skate skin gelatin may serve as candidates against hypertension and could be used as functional food ingredients.

Separation, Purification, and Identification of Angiotensin I–Converting Enzyme Inhibitory Peptides from Walnut (Juglans regia L.) Hydrolyzate

Walnut proteins were hydrolyzed with pepsin, alcalase, and papain. A peptide that strongly inhibits angiotensin I–converting enzyme was isolated and purified from walnut protein hydrolyzates via ultrafiltration, Sephadex G-25, Superdex™ Peptide 10/300 GL, and reversed phase high-performance liquid chromatography. The in vitro inhibition of angiotensin I–converting enzyme was used as an indicator. The molecular structure and sequences of the angiotensin I–converting enzyme inhibitory peptides were identified through mass spectrometry and amino acid sequencing. The angiotensin I–converting enzyme inhibitory peptide from the walnut hydrolyzate was identified as Tyr-Glu-Pro (YEP) and its median inhibitory concentration was 0.29μmol/L.

High-pressure improves enzymatic proteolysis and the release of peptides with angiotensin I converting enzyme inhibitory and antioxidant activities from lentil proteins

Angiotensin I converting enzyme (ACE) inhibitory and antioxidant peptides are receiving attention due to their beneficial effects in the prevention/treatment of hypertension. The objective was to explore the effect of high hydrostatic pressure (HP) on proteolysis by different proteases and the release of bioactive peptides from lentil proteins. Pressurisation (100–300MPa) enhanced the hydrolytic efficiency of Protamex, Savinase and Corolase 7089 compared to Alcalase. Proteolysis at 300MPa led to a complete degradation of lentil proteins and increased peptide (<3kDa) concentration by all enzymes. Proteolysis at 300MPa by Savinase gave rise to lentil hydrolysates (S300) with the highest ACE-inhibitory and antioxidant activities that were retained upon in vitro gastrointestinal digestion. The peptides responsible for the multifunctional properties of S300 hydrolysate were identified as different fragments from storage proteins and the allergen Len c 1. These results support the potential of HP as a technology for the cost-effective production of bioactive peptides from lentil proteins during enzymatic proteolysis.

A novel angiotensin-І converting enzyme (ACE) inhibitory peptide from gastrointestinal protease hydrolysate of silkworm pupa (Bombyx mori) protein: Biochemical characterization and molecular docking study

Silkworm pupa (Bombyx mori) protein was hydrolyzed using gastrointestinal endopeptidases (pepsin, trypsin and α-chymotrypsin). Then, the hydrolysate was purified sequentially by ultrafiltration, gel filtration chromatography and RP-HPLC. A novel ACE inhibitory peptide, Ala-Ser-Leu, with the IC50 value of 102.15μM, was identified by IT-MS/MS. This is the first report of Ala-Ser-Leu from natural protein. Lineweaver–Burk plots suggest that the peptide is a competitive inhibitor against ACE. The molecular docking studies revealed that the ACE inhibition of Ala-Ser-Leu is mainly attributed to forming very strong hydrogen bonds with the S1 pocket (Ala354) and the S2 pocket (Gln281 and His353). The results indicate that silkworm pupa (B. mori) protein or its gastrointestinal protease hydrolysate could be used as a functional ingredient in auxiliary therapeutic foods against hypertension.