• BMB Reports
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• v.30 no.6
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• pp.390-396
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• 1997

A sandwich-type enzyme-linked immunosorbent assay (ELISA) for the quantification of human apolipoprotein A-I (apoA-I) was developed using monoclonal antibodies. For this assay, we used three monoclonal antibodies to trap and detect apo A-I. HDAI16 and HDA15 monoclonal antibodies were used for trapping apoA-I and HDAI8 monoclonal antibody was for detecting apoA-I. These three monoclonal antibodies were produced by immunizing mice with high density lipoprotein (HDL) isolated from human plasma. By immunoblot analysis, these three monoclonal antibodies were specific to apoA-I and showed no cross-reactivities with other plasma proteins. The results of competition assays for epitope cross-reactivity test also verified that these monoclonal antibodies identified separate and distinct epitopes on HDL and apoA-I. Affinity constants of monoclonal antibodies were measured by ELISA. Their association constants ranged from $10^7$ to $10^8$ $M^{-1}$. For this assay, pure apoA-I was isolated by affinity chromatography using monoclonal antibodies. In this sandwich assay, the amount of HRP-labeled HDAI8 bound to apoA-I trapped by HDAI16 and HDAI5 was proportional to apoA-I concentration in the range of 0 to 500ng/ml. ApoA-I concentration in plasma was calculated from the linear regression equation of standard curve. The precision and reliability of the assays are reflected in the low intra-and interassay coefficients of variation that averaged 3.25% and 4.30%, respectively. This assay is sensitive, simple, reproducible, convenient in incubation interval, and does not use radioisotope: thus it can be widely applied in clinical laboratories.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.456-460
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• 1993

The present study was conducted to investigate Angiotensin I-converting enzyme(ACE) inhibition activity of the components of traditional tea materials in Korea. Angiotensin I-converting enzyme(ACE) inhibition activity of water soluble fractions obtained from the samples were strong in Zingiberis rhizoma, Acantopanacis cortex, Schizandrae fructus, Perilla semen, Cassiae torae semen, Zizyphy fructus in order. ACE inhibition activity of fractions obtained from methanol extract of Cassiae torae semen were strong in ethyl acetate fraction, ethyl ether fraction, water fraction, chloroform fraction in order. Compound C showed the strongest ACE inhibition activity among compound A, B, C, D separated from Cassiae torae semen, but Compound C separated from Cassiae torae semen was lower than bradykinin in the ACE inhibition activity.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.355-358
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• 2004

Chunkookjang, Korean traditional fermented soybean food emerges as a functional food to improve intestinal function and blood circulation. During Chungkookjang fermentation, microorganisms, enzymes, and diverse bioactive compounds increase sharply. Chungkookjang contains diverse oligo-peptides. Formation of peptides was confirmed by SDS-PAGE. Solube fermented soybean in our sample contained Tyr, Gln-Lys, Trp, Gln, and Lys-Pro as major components. Lys-Pro (0.083 mg/100 g sample) was purified by HPLC analysis. Angiotensin I­converting enzyme (ACE) causes hypertension by converting angiotensin I to angiotension II. ACE inhibitory activity of Lys-Pro was determined to be $IC_{50}=32.1\;{\mu}M.$ Whether or not eating Chungkookjang can lower blood pressure was also determined. Sistolic blood pressure dropped by 15 mmHg, and diastolic blood pressure by 8 mmHg 2 hr after a single administration of 20 g of fermented soybean. Chungkookjang might be helpful in improving blood circulation since it has ACE inhibitor and antihypertenisve effect.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.579-584
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• 1996

The molecular weight of the purified nucleoside oxidase estimated by gel filtration column chromatography was 480,000 and the enzyme protein was composed of four nonidentical subunits (81,000, 69,000, 32,000 and 16,000). On the basis of the visible absorption spectra and the enzymatic determination of the purified enzyme, the enzyme was supposed as a hemoprotein and also a flavoprotein containing 3 moles of FAD per I mole of enzyme. The isoelectric point of the enzyme was pH 5.1. Addition of metal salts such as 1 mM SnCl$_{2}$ and PbCl$_{2}$ into an enzyme reaction solution inhibited the enzyme activity by 94 and 90%, respectively. The enzyme activity was also lost significantly by hemoenzyme inhibitors such as NaCN and NaN$_{3}$ and flavoenzyme inhibitor, acriflavine and quinacrine. The maximal nucleoside oxidase activity was observed at pH 7.0 and 55$\circ$C. The nucleoside oxidase was relatively stable in the range of pH 5.5-9.0 and below 55$\circ$C.

• BMB Reports
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• v.32 no.2
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• pp.154-160
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• 1999

A calcium-independent phospholipase $A_2$ ($iPLA_2$) was identified from the cytosolic fraction of rat liver cells. On gel filtration chromatography, the $iPLA_2$ activity was eluted as broad peaks of 150 to 500 kDa. The enzyme was maximally active at pH 7.5, retained 75% of its original activity after heating at $50^{\circ}C$ for 5 h, and was inhibited by $Ca^{2+}$, $Mg^{2+}$, and $Zn^{2+}$ ions, but was not affected by $Na^+$ and $K^+$ ions. The enzymatic activity was increased up to 150% by 1 to 4 mM DTT and was inhibited up to 25% by 0.1 to 1 mM PMSF. The $iPLA_2$ activity had preference for the head group of phospholipids, where phosphatidylethanolamine was preferred to phosphatidylcholine. The results suggest that the $iPLA_2$ may be a novel enzyme distinct from the previously reported $iPLA_2s$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.226-233
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• 1993

Enzymatic hydrolysates of food proteins (defatted soybean cake, egg albumin and casein) were tested for inhibitory activity against angiotensin-I converting enzyme (ACE). Food proteins were hydrolysed with complex enzyme, bromelain, alcalase, $\alpha$-chymotrypsin, trypsin, papain and pepsin by heating method. The hydrolysates obtained from the treatment of complex enzyme and bromelain showed the higher ACE inhibitory activity. ACE inhibitory activity of hydrolysates exhibited a tendency to be increased until 8hrs and increased with increment of concentration. The activity was also stable by heat treatment at 10$0^{\circ}C$ for 20min. Molecular weight of active fraction was about 1, 400 and defatted soybean cake hydrolysate below 1, 400 in case of defatted soybean cake hydrolysate treated with alcalase. Amino acid of the active fractions was abundant in Asp, Glu, Lys, lle, Leu, Ala and Val.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.9
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• pp.1369-1373
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• 2003

ACE (Angiotensin-I converting enzyme) inhibitory peptides derived from foods are thought to suppress high blood pressure by inhibiting ACE. We tried to make efficient production of the ACE inhibitory hydrolysate from egg albumen. A hydrolysate digested by neutrase presented the highest ACE inhibitory activity ($IC_50\;value=256.35{\mu}g/ml$) and the proper proteolysis was occurred by 1.0% enzyme addition and 4 h incubation at $47^{\circ}C$. Antihypertensive effect of neutrase hydrolysate was investigated in spontaneously hypertensive rats (SHR, n=5). Systolic blood pressure (SBP) was decrease by 6.88% (-14.14 mmHg, p<0.05) at 3 h after oral administration of 300 mg/kg body weight, and by 13.33% (-27.72 mmHg, p<0.05) by emulsified hydrolysate. These results showed that it is very effective to utilize egg albumen as a protein source for the production of ACE inhibitory peptides. However, further studies are required to investigate the methods to increase recovery yield and the isolation of active peptide is necessary for determining its sequence responsible for ACE inhibitory activity.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.417-424
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• 2003

Inhibitory activities against angiotensin I-converting enzyme (ACE) of enzymatic hydrolysates of porcine skeletal muscle proteins were investigated. Myosin B, myosin, actin, tropomyosin, troponin and water-soluble proteins extracted from pork loin were digested by eight kinds of proteases, including pepsin, $\alpha$-chymotrypsin, and trypsin. After digestion, hydrolysates produced from all proteins showed ACE inhibitory activities, and the peptic hydrolysate showed the strongest activity. In the case of myosin B, the molar concentration of peptic hydrolysate required to inhibit 50% of the activity increased gradually as digestion proceeded. The hydrolysates produced by sequential digestion with pepsin and $\alpha$-chymotrypsin, pepsin and trypsin or pepsin and pancreatin showed weaker activities than those by pepsin alone, suggesting that ACE inhibitory peptides from peptic digestion might lose their active sequences after digestion by the second protease. However, the hydrolysates produced by sequential digestion showed stronger activities than those by $\alpha$-chymotrypsin, trypsin or pancreatin alone. These results suggested that the hydrolysates of porcine meat were able to show ACE inhibitory activity, even if they were digested in vivo, and that pork might be a useful source of physiologically functional factors.

• 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.

• BMB Reports
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• v.37 no.5
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• pp.552-555
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• 2004

Several studies have demonstrated the importance of angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) polymorphisms in the pathogenesis of hypertension. This study sought to determine the association between the ACE I/D polymorphism and essential hypertension in young Pakistanis. The frequency of the ACE I/D polymorphism was established by a comparative cross-sectional survey of Pakistani patients suffering from essential hypertension and ethnically matched normotensive controls. Samples were collected from tertiary care hospitals in northern Pakistan. Hypertensive individuals were defined as those with a systolic blood pressure > 140 mmHg and/or diastolic blood pressure > 90 mmHg on three separate occasions, or those currently receiving one, or more, anti-hypertensive agents. DNA samples obtained from hypertensive (n=211) and normotensive (n=108) individuals were typed by PCR. The frequency of the ACE I/I genotype was significantly higher in hypertensive patients, aged 20-40 years, than in normotensive controls of the same age group ($\chi^2$ = 4.0, P = 0.041). Whereas no overall significant differences were observed between the I/I, I/D and D/D ACE genotypes (One way ANOVA, F=0.672; P=0.413). The association between the ACE I/I genotype and essential hypertension in individuals aged $\leq$ 40 years suggests that ACE has a role in early onset essential hypertension in Pakistan.