Abstract Angiotensin I-converting Enzyme Research Articles

Callypyrones from marine Callyspongiidae sponge Callyspongia diffusa: antihypertensive bis-γ-pyrone polypropionates attenuate angiotensin-converting enzyme

Angiotensin I-converting enzyme (ACE) catalyses the biosynthesis of angiotensin II, a potent blood vessel constrictor, from angiotensin I, and ACE inhibitors were recognised as medications for hypertension. Undescribed bis-γ-pyrone polypropionate compounds, callypyrones A and B were purified from the organic extract of Callyspongiidae sponge species Callyspongia diffusa by repeated chromatographic purification. Callypyrone A exhibited significantly greater attenuation potential against ACE (IC50 0.48 mM) than that displayed by callypyrone B (IC50 0.57 mM) and showed comparable activity with standard ACE inhibitor captopril (IC50 0.36 mM). Higher electronic parameters of callypyrone A (topological surface area of 108.36) combined with balanced hydrophilic-lipophilic parameter (octanol–water coefficient, log P ow 1.9), as deduced from the structure–activity relationship analyses, could further indicate the improved ligand–receptor interactions resulting in its prospective ACE inhibitory activity. In silico docking analyses of the callypyrones with ACE recorded lowest binding energy (–12.58 kcal mol−1) for callypyrone A, which further supported the antihypertensive potential of the compound.

Clinical impact of angiotensin I converting enzyme polymorphisms in subjects with resistant hypertension.

Angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphism is thought to affect renin-angiotensin system (RAS) activity and development of cardiovascular disease; significant associations between I/D polymorphism and atherosclerosis, stroke, nephropathy, and early mortality were already found. We investigated whether Southern Italy resistant hypertensives presented an association between the presence of I and/or D alleles and early vascular damage, inflammation, and insulin resistance. One-hundred-fifty resistant hypertensives were enrolled, studied, and genotyped; carotid intima-media thickness (cIMT), arterial stiffness (AS), and HOMA indices were also evaluated. D allele was more prevalent, and 74 patients presented DD homozygosis. Sixty-eight patients had metabolic syndrome (MetS), without significant differences between DD and I allele carriers. DD genotype appeared strongly associated with higher HOMA values (p < 0.001), and also with both Augmentation Index (AIx, p = 0.003) and Pulse Wave Velocity (PWV, p = 0.023). A significant association was found between DD genotype and cIMT (p < 0.005), while no association between ACE genotype and the presence of carotid plaques. HOMA was correlated with AS (PWV: p < 0.001; AIx: p < 0.01). DD genotype appeared to be associated with AS and HOMA index, but not with inflammation, independently from blood pressure values and the presence of other MetS factors, confirming D allele as an independent risk marker. Vascular damage may develop and progress independently from other risk factors in resistant hypertensives, likely through the interplay between ACE gene, RAS activity, and insulin resistance.

Angiotensin I-Converting Enzyme Inhibitory Effect of Chinese Soypaste Along Fermentation and Ripening: Contribution of Early Soybean Protein Borne Peptides and Late Maillard Reaction Products

Angiotensin I-converting enzyme inhibitory effect of Chinese soypaste was investigated during 4-month fermentation and ripening. This effect increased significantly at early stage and reached a plateau until the end of ripening, with an IC50 value of 0.436 mg/mL for the final product. Peptide and reducing sugar contents increased drastically during early fermentation and declined afterward. Maillard reaction took place continuously as indicated by consistent accumulation of precursor, intermediate, and final Maillard reaction products monitored by fluorescence, ultraviolet-absorbance and absorbance at 420 nm, respectively. During early fermentation, peptides were principal compounds responsible for the angiotensin I-converting enzyme inhibitory effect. During late ripening, angiotensin I-converting enzyme inhibition by Maillard reaction products could compensate for the loss of the effect caused by the utilization of peptides, and enable the total effect to remain at a good and steady level, suggesting an indispensable contribution of Maillard reaction products to angiotensin I-converting enzyme inhibitory effect of soypaste, particularly in products with prolonged maturation.

Comparison of ACE inhibitory activity in skimmed goat and cow milk hydrolyzed by alcalase, flavourzyme, neutral protease and proteinase K

Abstract Angiotensin I converting enzyme (ACE) inhibitory peptides derived from milk proteins have obvious effect of lowering blood pressure, safe and non-toxic side effects. This study compared four commercial proteases, namely alcalase, flavourzyme, neutral protease and proteinase K for their ACE inhibitory activity in skimmed goat and cow milk and identified the best one with higher ACE inhibitory activity. The degree of hydrolysis (DH) of alcalase and proteinase K were much higher than flavourzyme, neutral protease for both skimmed goat and cow milk. Alcalase was the best enzyme to produce ACE inhibitory peptides from goat milk, with the ACE inhibitory activity 95.31%, while proteinase K was the optimal protease for hydrolyzing cow milk, with 81.28% ACE inhibitory activity. Furthermore, no correlation was obtained between the ACE inhibitory activity and DH for both goat and cow milk.

Application of Electrolyzed Water to Improve Angiotensin I-Converting Enzyme Inhibitory Activities of Fermented Soybeans Started with Bacillus Subtilis B1

Angiotensin I-converting enzyme (ACE) inhibitory activities of soybeans fermented by Bacillus subtilis B1 with pretreatment of soaking in electrolyzed oxidizing (EO) water, electrolyzed reduced (ER) water, chemically modified acidic and alkaline solutions as well as conventional tap water were investigated. Using electrolyzed water improved significantly (p < 0.05) the ACE inhibitory activities of fermented soybeans as compared with using tap water. The highest ACE inhibitory activity was recorded as an IC50 value of 0.065 mg/mL in the sample, which had been pretreated by soaking in ER water prior to fermentation. The ACE inhibitory activity increased to and tended to keep at a higher level during fermentation of EO water-soaked soybeans. However, there was no evident advantage of chemically modified acidic and alkaline solutions over tap water. Results suggested that electrolyzed water possessed potent ability to improve the ACE inhibitory activity of fermented soybeans, which might be through providing an appropriate microenvironment for the hydrolytic actions of microorganism to generate ACE inhibitors. In addition, this work also suggested a potential ability of electrolyzed water to be applied into the production of functional foods.

Antihypertensive Effect of Angiotensin-Converting Enzyme Inhibitory Peptide Obtained from Hen Ovotransferrin

Angiotensin I-converting enzyme (ACE) inhibitory peptide was isolated from the hen ovotransferrin hydrolysate using chymotryptic hydrolysis by two steps of reverse-phase high-performance liquid chromatography. The amino sequence of this novel peptide was identified as Lys-Val-Arg-Glu-Gly-Thr-ThrTyr that inhibited ACE activity in vitro in a concentration-dependent manner with an effective concentration(IC50)of102.8M.Also,thisinhibitionwasidentifiedasnoncompetitiveusingtheLineweaver-Burk plot.Moreover,theantihypertensiveactionofthisnovelpeptidewasinvestigatedbyanintravenousinjection into spontaneously hypertensive rats (SHR). A dose-dependent reduction of systolic blood pressure by this peptide was observed after 40 min of treatment and it decreased the blood pressure markedly at the maximal dose (1 nmol/mL/kg). The maximal blood pressure lowering activity of this peptide was calculated as 163% of captopril (10 pmol/mL/kg) that was used as positive control. In conclusion, the obtained data suggests that Lys-Val-Arg-Glu-Gly-Thr-Thr-Tyr has an ability to inhibit ACE activity and decrease the systolic blood pressure in hypertensive animals.

In vitro intestinal transport and antihypertensive activity of ACE inhibitory pea and whey digests

Angiotensin I converting enzyme (ACE) inhibitory peptides cause an antihypertensive effect if they reach the systemic circulation. This was investigated for the high ACE inhibitory activity present in peas and whey in vitro gastrointestinal digests. The samples retained high ACE inhibitory activity when incubated in Caco-2 homogenates or rat intestinal acetone powder, both sources of small intestine peptidases. Only little ACE inhibitory activity was transported through Caco-2 cell monolayers in 1 h. As the Caco-2 model is tighter than intestinal mammalian tissue, sufficient absorption of these peptides might occur in vivo. After intravenous administration of 50 mg protein kg−1 BW in spontaneously hypertensive rats (SHR), pea digest exerted a transient, but strong antihypertensive effect of 44.4 mmHg. Whey digest exerted no effect at this dose. These results suggest that pea digest could be a promising source of ACE inhibitory peptides for use in the prevention and treatment of hypertension.

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ABSTRACT Angiotensin-
Iconverting enzyme(ACE)inhibitor was isolated from beef by-products. The beef by- product hydrolysates prepared with various proteases were tested for the inhibitory effects against ACE. The proteases used were proteinase A from bakers yeast, protease type
O
I
fungal and thermolysin. The maximum inhibitory effect was observed after hydrolysis for 12hrs(beef heart) and 24hrs(beef spleen), respectively. After gel filtration, IC 50 value was 0.37mg/L
in beef heart and 1.84mg/L
in beef spleen. After RP-HPLC, the IC 50 value of peak 1, peak 2, peak 3 and peak-4 were 0.28mg/L, 0.26mg/L, 0.25mg/L
and 0.35mg/L, respectively. In the results of amino acid composition of peak 1, peak 2, peak 3 and peak 4, it was observed that peak 1 was consisted mainly of glycine and methionine, peak 2 was proline, cystine and methionine, peak 3 was proline and peak 4 was alanine, methionine and leucine. In conclusion, beef heart hydrolysate treated with thermolysin+ proteinase A was shown to have the highest inhibitory effect for 12hrs incubation at 37.(

Epitope-specific antibody-induced cleavage of angiotensin-converting enzyme from the cell surface

Angiotensin I-converting enzyme (ACE; CD143, EC 3.4.15.1) is a type-1 integral membrane protein that can also be released into extracellular fluids (such as plasma, and seminal and cerebrospinal fluids) as a soluble enzyme following cleavage mediated by an unidentified protease(s), referred to as ACE secretase, in a process known as "shedding". The effects of monoclonal antibodies (mAbs) to eight different epitopes on the N-terminal domain of ACE on shedding was investigated using Chinese hamster ovary cells (CHO cells) expressing an ACE transgene and using human umbilical vein endothelial cells. Antibody-induced shedding of ACE was strongly epitope-specific: most of the antibodies increased the shedding by 20-40%, mAbs 9B9 and 3A5 increased the shedding by 270 and 410% respectively, whereas binding of mAb 3G8 decreased ACE shedding by 36%. The ACE released following mAb treatment lacked a hydrophobic transmembrane domain anchor. The antibody-induced shedding was completely inhibited at 4 degrees C and by zinc chelation using 1,10-phenanthroline, suggesting involvement of a metalloprotease in this process. A hydroxamate-based metalloprotease inhibitor (batimastat, BB-94) was 15 times more efficacious in inhibiting mAb-induced ACE shedding than basal (constitutive) ACE release. Treatment of CHO-ACE cells with BB-94 more effectively prevented elevation in antibody-dependent (but not basal) ACE release induced by 3,4-dichloroisocoumarin and iodoacetamide. These data suggest that different secretases might be responsible for ACE release under basal compared with antibody-induced shedding. Further experiments with more than 40 protease inhibitors suggest that calpains, furin and the proteasome may participate in this process.

Inhibition of angiotensin-converting enzyme by peptides from the venom of the viperEchis multisquamatus

Angiotensin I-converting enzyme [dipeptidyl carboxypeptidase] (ACE, CE 3.4.15.1) isolated in the pure form from ox kidney, has been characterized physicochemically and kinetically. Inhibition of the enzyme by homogeneous peptides from the venom of the Central Asian viperEchis multisquamatus Ch. has been investigated.

Angiotensin I converting enzyme activity in uranyl nitrate induced acute renal failure in rats.

Angiotensin I converting enzyme (ACE) was measured in urine, serum, and tissues from rats with acute renal failure (ARF) induced by a single subcutaneous injection (15 mg/kg BW) of uranyl nitrate (UN). Urine was collected daily until day 5, when rats were sacrificed by decapitation for the obtention of blood serum and tissues. Other groups of rats were sacrificed on days 1 and 2. These rats showed proteinuria and polyuria. The damage to the kidney proximal tubule was shown by (a) histological analysis at light and electron microscopy levels on days 1, 2, and 5, (b) the increase in urinary excretion of dipeptidyl aminopeptidase IV and N-acetyl-beta-D-glucosaminidase on days 1-5, and (c) the low molecular weight proteinuria pattern on day 1. In addition, the histological analysis at the ultrastructural level showed normal glomeruli appearance on days 1 and 2, but structural alterations on day 5. These data suggest that the increased urinary excretion of enzymes and proteins is a consequence of the tubular injury on days 1 and 2, and of tubular and glomerular injury on day 5. ACE activity increased in urine on days 1-5 and in serum on day 5. Tissue ACE activity increased in lung, small intestine, and adrenal glands; and remained unchanged in testis, aorta, brain, kidney, heart, and liver. Our data suggest that: (a) the increase in serum ACE may be secondary to the changes in tissue ACE activity, and (b) the urine ACE increase may be due to the kidney proximal tubule damage. This work supports the contention that an increase in urine ACE may be an indicator of injury to the proximal tubule.

Angiotensin I converting enzyme in glycerol-induced acute renal failure in rats.

Angiotensin I converting enzyme (ACE) activity was measured in serum, urine, and tissues of rats with acute renal failure (ARF) induced by glycerol. Glycerol-injected rats were subdivided in three groups according to the urinary volume: oliguric, nonoliguric, and polyuric. The damage to the proximal tubule was evident by (a) the histological analysis at light and electron microscopy level, (b) the augmented urinary excretion of the enzymes dipeptidyl aminopeptidase IV and N-acetyl-beta-D-glucosaminidase, and (c) the low molecular weight proteinuria pattern. On the other hand, the appearance of the glomeruli at the ultrastructural level was normal. These data suggest that the increased urinary excretion of enzymes and proteins in these rats is a consequence of the tubular injury. ARF was markedly higher in the oliguric rats. Urine ACE activity increased in the rats of the three groups, but statistical significance was reached only in the oliguric rats. Serum ACE activity increased in the oliguric rats and tissue ACE activity did not change. It is concluded that the high urinary ACE in glycerol-treated rats is associated with the damage to the kidney tubules. These data support the contention that urinary ACE may be another marker of injury to the proximal tubule.

No effect of insertion/ deletion polymorphism at the ACE locus on normal blood pressure level or variability

Angiotensin I-converting enzyme (ACE) cleaves angiotensin I to angiotensin II, which is the active component in the renin-angiotensin system (RAS). We have studied an insertion/deletion polymorphism in DNA at the ACE locus. In three different series comprising 140, 90 and 136 unrelated individuals we found no evidence of association between genotypes in this insertion/deletion (I/D) polymorphism and level of systolic or diastolic blood pressure. In two series of 130 and 88 monozygotic (MZ) twin pairs, respectively, there was no difference between genotypes in within-pair variation in systolic or diastolic blood pressure. Thus, in these series of healthy people, neither "level gene" nor "variability gene" effects of this insertion/deletion polymorphism were observed.

Characterization of chicken lung angiotensin I-converting enzyme.

Angiotensin I(AI)-converting enzyme (ACE) (EC 3.4.15.1) was solubilized from the membrane fraction of chicken lung using trypsin and nonidet P40 extraction, and then purified to homogeneity by captopril affinity chromatography. Comparison of trypsin-extracted and detergent-solubilized membrane-bound converting enzyme by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and isoelectric focusing indicated that the membrane-binding sequence contributed to a large extent to the size and charge of the enzyme. Both forms of the enzyme were glycoproteins but they differed in the glucidic content; 4.5% by weight of the enzyme in the trypsin-extracted ACE and 15% by weight of the enzyme in the detergent-solubilized ACE. In both cases hexoses were the most abundant residues. Both forms of the enzyme were found to contain 1 g-atom zinc/mol enzyme. The purified enzymes did not only split Hip-His-Leu but also AI and bradykinin. The Michaelis constant (Km) and maximum velocity (Vmax) values of the trypsin-extracted ACE for Hip-His-Leu were 52 x 10(-5) mol/l and 15.36 nmol/min respectively, and for AI they were 7.8 x 10(-5) mol/l and 0.45 nmol/min respectively. The Km and Vmax values of the detergent-solubilized ACE for Hip-His-Leu were 32 x 10(-5) mol/l and 11.75 nmol/min respectively, and for AI they were 6.5 x 10(-5) mol/l and 0.97 nmol/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Perinatal development of angiotensin-converting enzyme in the rat's blood.

Angiotensin-I-converting enzyme (ACE) activity was measured by a fluorimetric technique in serum samples taken from rat fetuses and their mothers. The samples were collected from anesthetized rats on consecutive days from day 18 of gestation to day 22 (day of delivery) and one day after birth. Fetal ACE activities were significantly higher than the corresponding maternal values which remained nearly unchanged during pregnancy. No dramatic changes in serum ACE activity of the developing fetuses could be observed.

Biological regulation of testicular angiotensin I-converting enzyme.

Angiotensin I-converting enzyme (ACE) from rat testes and lung was purified to homogeneity and partially characterized with respect to physicochemical parameters. Additionally, the biological regulation of testicular ACE by gonadotropins and androgens was investigated was investigated and the cell type with which ACE is associated in testes was identified. Rat testicular ACE is a lower molecular weight, isozymic version of the lung enzyme. Partial proteolysis of each isozyme produces different peptide maps, suggesting unique primary structures for each protein. The sensitivity of each isozyme to Co2+, chelators and thermal denaturation is different, a finding that further supports the hypothesis that structural differences exist between the two isozymes. The pituitary gland is essential for the development during puberty and maintenance during adulthood of testicular ACE. In hypophysectomized mature rats, gonadotropins or androgen can maintain ACE activity to near sham-operated levels. ACE activity in testes appears to be associated almost entirely with various stages of germinal cell development. The function(s) of testicular ACE awaits definition. The mechanism of androgen-maintenance of testicular ACE is unclear. Whether androgen specifically induces gene expression of testicular ACE or simply allows for ACE activity to develop in parallel with spermatogenesis is an unresolved question.

Angiotensin I converting enzyme activity in rabbit corneal endothelial cells.

Angiotensin I converting enzyme (ACE) was studied in Vero cells, rabbit corneal fibroblasts, and rabbit corneal endothelial cells. The enzyme activity was determined by means of an assay employing hippuryl-glycyl-glycine as a substrate. The hippuric acid end product was separated from the substrate by reversed phase liquid chromatography and measured spectrophotometrically at 228 nm. The enzyme was further characterized by a captopril inhibition study. Significant ACE activity was found in rabbit corneal endothelial cells but not in other types of cells tested. This is the first report of the presence of this enzyme in a specific ocular cell type and suggests that angiotensin II may play a role in normal ocular physiology.