• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.118-125
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• 2011

In this study, an angiotensin I-converting enzyme (ACE) inhibitor from squid skin was purified and characterized. Squid (Todarodes pacificus) skin protein isolates were hydrolyzed using six commercial proteases: alcalase, ${\alpha}$-chymotrypsin, neutrase, papain, pepsin, and trypsin. The peptic hydrolysate had the highest ACE inhibitory activity. The ACE inhibitory peptide was purified using Sephadex G-25 column chromatography and reverse phase high-performance liquid chromatography (HPLC) with a $C_{18}$ column. The purified ACE inhibitory peptide was identified and sequenced, and found to consist of seven amino acid residues: Ser-Ala-Gly-Ser-Leu-Val-Pro (657Da). The $IC_{50}$ value of the purified ACE inhibitory peptide was 766.2 ${\mu}M$, and Lineweaver-Burk plots suggested that the purified peptide acts as a noncompetitive ACE inhibitor. These results suggest that the ACE inhibitory peptide purified from the peptic hydrolysate of squid skin may be of benefit in developing antihypertensive drugs and functional foods.

• Preventive Nutrition and Food Science
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• v.20 no.3
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• pp.176-182
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• 2015

Abalone protein was hydrolyzed by enzymatic hydrolysis and the optimal enzyme/substrate (E/S) ratios were determined. Abalone protein hydrolysates (APH) produced by Protamex at E/S ratio of 1:100 showed angiotensin I converting enzyme inhibitory activity with $IC_{50}$ of 0.46 mg/mL, and APH obtained by Flavourzyme at E/S ratio of 1:100 possessed the oxygen radical absorbance capacity value of $457.6{\mu}M$ trolox equivalent/mg sample. Flavourzyme abalone protein hydrolysates (FAPH) also exhibited $H_2O_2$ scavenging activity with $IC_{50}$ of 0.48 mg/mL and $Fe^{2+}$+ chelating activity with $IC_{50}$ of 2.26 mg/mL as well as high reducing power. FAPH significantly (P<0.05) protected $H_2O_2$-induced hepatic cell damage in cultured hepatocytes, and the cell viability was restored to 90.27% in the presence of FAPH. FAPH exhibited 46.20% intracellular ROS scavenging activity and 57.89% lipid peroxidation inhibition activity in cultured hepatocytes. Overall, APH may be useful as an ingredient for functional foods.

• Journal of Life Science
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• v.8 no.3
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• pp.312-317
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• 1998

This study was designed to investigate the angiotensin convertin enzyme (ACE) inhibitory activity of skipjack/yellowpin tuna cooking broth. The cooking broth was pretreated with membrane filter (MW cut-off 5,000) to obtain the peptide fraction with ACE inhibition. the crude peptides fractionated with Amberlite IR-120 ($H^{+}$ form and followed by Bio-gel P-2, were separated into nine fractions (T-1 to T-9). The maximum inhibitory activity was observed in the fraction T-4 ($IC_{50}$ value, 0.619mg/ml). The abundant amino acids obtained from active fraction T-4 were phenylaanine, leucine and glutamic acid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.737-742
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• 2000

As functionality investigation of a soybean fermentation food, a angiotensin converting enzyme inhibitory peptide was separated during natto fermentation by Bacillus natto and inhibitory effect was investigated. After incubation at each 2$0^{\circ}C$, 3$0^{\circ}C$, 4$0^{\circ}C$, 5$0^{\circ}C$, 6$0^{\circ}C$ for the 0~72 hr, protein content, protease activity and angiotensin converting enzyme inhibition were determined. The protein content and protease activity were increased and reached maximum at 60 hr fermentation with 4$0^{\circ}C$ and decreased after the 60 hr fermentation during natto fermentation. The optimum condition for angiotensin converting enzyme inhibitors was appeared at fermentation for 60 hr at 4$0^{\circ}C$. Crude extract of natto was partially purified by Amicon membrane YM-3 and Sephadex G-10, G-25 gel filtration, stepwise. The inhibitory rate was increased in a concentration dependent manner, espcially the most potent activity about 74.74% at 1.0 mg peptide content. The most prominent amino acid of the peptide from natto was alanine, followed by phenylalnine, histidine.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.9-14
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• 2010

In this study, lactic acid bacteria with high angiotensin converting enzyme inhibitor activity were isolated from Korean fermented food, such as kimchi and salted seafood. The strain HLJ59, isolated from salted shrimp showed the highest angiotensin converting enzyme inhibitor activity in DeMan Rogosa Sharpe broth. Optimum growth temperature of Lactobacillus brevis HLJ59 was at $34^{\circ}C$. Acid treatment at pH 3.0 for 1.5 h decreased cell viability from $9.9{\times}10^8$ CFU/ml to $3.11{\times}10^4$ CFU/ml. The bile extract concentration of 0.3%, 0.5%, and 1.0% in MRS broth did not inhibit the growth of HLJ59. Isolated strain HLJ59 showed more sensibility to amikacin, gentamycin, neomycin, streptomycin, kanamycin, cefmetazole, cephalothin, ampicillin, ticarcillin, sulbactam+ampicillin, amoxicillin+clavulanic acid (AMC), tetracycline, and sulfamethoxazole+trime thoprim (SXT) as compare to other 7 different antibiotics. However, it showed more resistance to cefoxatin, ceftnaxone, penicillin, ciprofloxacin, nalidixic acid, lincomycin, and chloramphenicol.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.135.2-135
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• 2003

Angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II by cleaving C-terminal dipeptide of angiotensin I and inactivates bradykinin. ACE inhibitors have been screened from various food sources since the inhibitors decrease blood pressure. Therefore, in this study, an ACE inhibitor was isolated and purified from squid ink using membrane filtration, gel permeation chromatography, normal phase HPLC, and fast protein liquid chromatography. The purified inhibitor was identified to be a molecular mass of 294 by mass spectrometry, and to have IC$\sub$50/ value of 4.9 $\mu\textrm{g}$/mL.

• The Journal of Korean Medicine
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• v.22 no.2
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• pp.3-9
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• 2001

Objective : Oriental medicinal plants reported to be used as anti-hypertensive drugs have been in vitro screened for inhibitory effects on angiotensin-converting enzyme (ACE). Methods : The bioassay is based on inhibition of plasma angiotensin-converting enzyme, as measured from the enzymatic cleavage of the Hip-His-Leu substrate into His-Leu. The plant material is extracted with hexane, ethylacetate, n-buthanol and water separately. Results : In total, 51 species (202 extracts) have been investigated and $400{\;}\mu\textrm{g}/ml$ of the solvent extracts from 26 extracts inhibit the enzyme activities by more than 50%. Among them, four samples of two plant species (buthanol and ethylacetate extracts of Salvia miltiorrhiza and buthanol and water extracts of Jeffersonia dubia) were found to posses a high ACE inhibition ability more than 90%. Conclusion : These results suggested that many Oriental medicinal plants have a antihypertensive effects by inhibition of ACE.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.177-181
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• 2009

The peptides from Aroase AP10 enzymatic hydrolysates of octopus proteins were isolated and tested for inhibitory activity against angiotensin converting enzyme (ACE). The Aroase AP10 hydrolysates were filtered through PM-10 membrane (M.W. cut-off 10,000) to obtain the peptides fractions with ACE inhibition activity. These fractions were applied to a Biogel P-2 column. Three active fractions (A, B, and C) were collected and applied to a SuperQ-Toyopearl 650S column chromatography, leading to the isolation of four active fractions (A-1, A-2, B-1, and C-1). Among the active fractions, C-1 had the highest ACE inhibitory activity ($IC_{50}=3.10{\mu}g$). The main composition of its amino acids is arginine, lysine, histidine and leucine, which cover about 60% of the total amino acids.

• Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.109-112
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• 2005

A peptide that inhibits angiotensin-converting enzyme (ACE) was isolated from a hydrolysate of Manila clam (Ruditapes philippinarum) proteins prepared with thermolysin. Amino acid sequence of the peptide was determined to be Leu-Leu-Pro. Chemically synthesized Leu-Leu-Pro had an $IC_{50}\;value\;of\;158\;\mu{M}$. Peptides related to the Manila clam-derived peptide were synthesized to study the structure-activity relationships. The tetrapeptide, Leu-Leu-Pro-Pro, had a very weak effect on the enzyme. However, Leu-Leu-Pro-Asn showed no inhibitory activity.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.848-854
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• 1999

Inhibitory compounds of angiotensin converting enzyme (ACE) were separated from Doenjang (traditional Korean fermented soybean paste). Water extracts from Doenjang which showed ACE inhibitory activity were separated with gel permeation chromatography (GPC), in which two fractions with high ACE inhibitory activities were obtained. The first fraction from GPC was further isolated by semi-preparative reverse phase preparative-HPLC (high performance liquid chromatography) and 2-dimensional electrophoresis/thin layer chromatography (TLC). The purified spot had molecular weight of 759 daltons and ninhydrin-positive non-peptide. The second fraction from GPC was also further isolated by semi-preparative reverse phase HPLC and $NH_2-column$ HPLC. One fraction with high ACE inhibitory activity was purified and characterized. Molecular weight of this fraction by LC-MS was 272.34 daltons. The active fraction was identified as Arg-Pro with ACE $IC_{50}$ of $92\;{\mu}M$.