Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.15.1 (ACE)
 18,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Angiotensin I-converting enzyme (EC 3.4.15.1) has been purified to electrophoretic homogeneity from chicken lung by using a facile two-step protocol which included affinity chromatography on Sepharose-bound captopril. 2. Captopril was a potent inhibitor of chicken lung angiotensin I-converting enzyme with Ki values of 2.0 nmol/l and 1.6 nmol/l for detergent-extracted and trypsin-extracted angiotensin I-converting enzymes, respectively. 3. Molecular weight comparison of trypsin-extracted (M(r)270,000) and detergent-extracted (M(r)690,000) angiotensin I-converting enzyme indicated that membrane-binding sequence contributed to a large extent to the enzyme molecule. 4. Kinetic properties of both forms of the enzyme suggested that the membrane-bound sequence contributed to an increase of the enzyme-substrate affinity.
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PMID:Inhibition and affinity chromatography of chicken lung angiotensin I-converting enzyme with captopril. 132 42

1. To examine the effect of chronic administration of angiotensin I-converting enzyme (ACE) inhibitor on circulating angiotensin II (AII) concentration, 20 mg of lisinopril was administered once daily for 7 consecutive days to eight healthy volunteers. 2. Plasma ACE activity was inhibited to less than approximately 30% of the pretreatment level during the repeated administration. 3. Mean arterial pressure (MAP) was slightly but significantly reduced during the administration period. Plasma AII concentration measured by an established method using high performance liquid chromatography combined with a radioimmunoassay, however, was maintained at approximately the pretreatment level when it was measured at 24 h intervals after each administration of lisinopril. 4. With the gradual recovery of ACE activity following discontinuation of administration, the plasma AII concentration correlated with AI concentration (r = 0.46), and also with the product of AI and ACE activity (AI x ACE; r = 0.80), corresponding to the formula obtained from the kinetics of ACE activity. No correlation was observed between MAP and AII levels throughout the study period. 5. We conclude that in normal subjects repeatedly administered with ACE inhibitor, the AII level in the circulation is still determined by an elevated level of AI and any remaining ACE activity, thus maintaining AII at pretreatment levels. We confirmed that it is not necessary to achieve a decrease in plasma AII concentration through the chronic administration of ACE inhibitor in order to effectively lower blood pressure.
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PMID:Circulating angiotensin II levels under repeated administration of lisinopril in normal subjects. 132 22

In the present studies, ex vivo-, in vitro-, and in vivo-effects of three structurally different angiotensin I-converting enzyme (ACE) inhibitors on the kallikrein-kinin and eicosanoid systems are described. In the ex vivo- and in vitro-experiments using isolated rat aorta, vascular prostacyclin (PGI2) production is dose-dependently stimulated by the ACE inhibitors captopril, lisinopril, and ramipril. Furthermore, the ACE inhibitor-induced augmentation of vascular PGI2 synthesis observed in vitro was completely inhibited by the competitive bradykinin antagonist D-Arg[Hyp3,Thi5,8,D-Phe7]bradykinin suggesting that ACE inhibitors stimulate PGI2 generation by an enhancement of kinin activity. In the in vivo studies in healthy volunteers, we used platelet cyclic adenosine-5'-monophosphate (cAMP) and cyclic guanosine-5'-monophosphate (cGMP) as indirect parameters of the activity of prostacyclin and the endothelium-derived relaxing factor, respectively. Since platelet cAMP and cGMP were unaffected by an acute dose of 10 mg of lisinopril, our data do not support the concept that the interference of ACE inhibitors with the kallikrein-kinin-prostaglandin system observed ex vivo and in vitro participates in the haemodynamic effects of these agents in humans in vivo.
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PMID:ACE-inhibition, kinins, and vascular PGI2 synthesis. 133 54

Elevated serum angiotensin I-converting enzyme activity may occur in diabetic subjects. This may signal alteration of vascular endothelium. To study the effect of acute glucose change on serum Angiotensin Converting Enzyme (ACE), we performed an oral glucose tolerance test in 17 obese subjects (7M/10F), (Body Mass Index, (BMI): 31 +/- 1 kg/m2), aged 48 +/- 3 years. We measured serum ACE activity (Lieberman's method), active renin (RIA Pasteur kit), and aldosterone (RIA, Cis-International kit), before and 2 hours after oral glucose intake (75 g), and plasma glucose and insulin every 30 min. After oral glucose tolerance test, subjects were classified as 6 Non Insulin-Dependent Diabetic (NIDD), 8 Glucose intolerant (GI), and 3 NormoGlycaemic (NG) subjects. Active renin did not vary after glucose loading (14 +/- 2 vs 15 +/- 2 pg/ml) nor aldosterone (104 +/- 14 vs 133 +/- 18 pg/ml), while ACE activity rose significantly (229 +/- 25 vs 277 +/- 28 IU/l; p = 0.02). Serum ACE activity were different in the 3 groups before glucose loading (NIDD: 266 +/- 37, GI: 252 +/- 32, NG: 90 +/- 21 IU/l; Kruskal-Wallis H = 7.03; p = 0.03), but not after 2 hours (NIDD: 297 +/- 42, GI: 275 +/- 36, NG: 204 +/- 113 IU/l; ns).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Increase of angiotensin converting enzyme activity during oral load of glucose]. 133 58

The ovarian renin-angiotensin system (RAS) has been studied extensively in the virgin cycling rat, but little information is available about this system in pregnant and postpartum rats. We show that renin and angiotensin I-converting enzyme (ACE)--the key enzymes involved in angiotensin II (Ang II) formation--and Ang II receptors, are present in pregnant and postpartum rat ovaries. From gestation Days 2-4 to 10-12, active ovarian renin ranged from 1.12 +/- 0.13 to 1.27 +/- 0.19 ng Ang I/h/mg and comprised between 68 and 86% of total (active+inactive) ovarian renin activity. Between Days 10-12 and Days 14-16 of pregnancy, ovarian active renin activity increased slightly, but inactive renin disappeared, suggesting its activation; the remaining active renin then decreased 62% by Days 18-20 (p < 0.05). On postpartum Day 2, both active and total ovarian renin activity exceeded that of Days 2-20 of pregnancy (p < 0.05); levels of both then declined sharply by postpartum Day 3 (p < 0.05). In pregnant rats, levels of ovarian Ang II receptors, identified by the specific binding of [125I]-[Sar1,Ile8]Ang II to ovarian membranes, were high between Days 2-4 and 10-12 of pregnancy, ranging from 12.8 +/- 1.7 to 15.7 +/- 3.4 fmol/mg, but steadily declined by 82% between gestation Days 10-12 and 18-20 (p < 0.05). Postpartum Ang II receptor levels on Days 2, 3, and 4 showed a gradual increase from low levels comparable to Days 18-20 of pregnancy. Ovarian ACE activity did not change throughout pregnancy or during the postpartum period.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rat ovarian angiotensin II receptors, renin, and angiotensin I-converting enzyme during pregnancy and the postpartum period. 133 75

The angiotensin I-converting enzyme (kininase II, ECA) is a membrane bound enzyme anchored to the cell membrane through a single transmembrane domain located near its carboxyterminal extremity. Secretion of ACE by the cell occurs most likely as a result of a posttranslational cleavage of the membrane anchor and intracellular region. The ACE molecule is organized into two large highly homologous domains, each bearing consensus sequences for zinc binding in metallopeptidases. Site directed mutagenesis allowed to establish that both domains bear in fact a functional active site, able to convert angiotensin I into angiotensin II and to hydrolyze bradykinin or substance P. The two active sites of ACE, however, do not display the same sensitivity to anion activation (the C terminal active site being more chloride activatable) and also differs in kinetic parameters for peptide hydrolysis. The C terminal active site can hydrolyze faster angiotensin I and substance P and the N terminal active site is able to perform a peculiar endoproteolytic cleavage of an in vitro substrate of ACE, the luteinizing hormone releasing hormone. Both active sites bind with a high affinity, competitive inhibitors but the Kd of the reaction can vary up to 10 between the two active sites. All together, these observations suggest that ACE contains two active sites, whose structure is not exactly identical. They may have a different substrate specificity, however this remains speculative at the present time. Concerning the regulation of ACE gene expression in man, population studies indicated that the large interindividual variability in plasma ACE levels is genetically determined. An insertion/deletion polymorphism located in an intron of ACE gene is associated with differences in the level of ACE in plasma and cells. The physiological and clinical implications of these observations is discussed.
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PMID:[Angiotensin converting enzyme (kininase II). Molecular and physiological aspects]. 133 89

Dried bonito (Katsuobusi), a Japanese traditional seasoning made of bonito muscle was hydrolyzed by various proteases and the inhibitory activity of the hydrolyzates for angiotensin I-converting enzyme (ACE) [EC 3.4.15.1] was measured. Among the digests, thermolysin digest showed the most potent inhibitory activity. Eight inhibitory peptides were isolated from the digest using HPLC. The amino acid sequences of inhibitory peptides were Ile-Lys-Pro-Leu-Asn-Tyr, Ile-Val-Gly-Arg-Pro-Arg-His-Gln-Gly, Ile-Trp-His-His-Thr, Ala-Leu-Pro-His-Ala, Phe-Gln-Pro, Leu-Lys-Pro-Asn-Met, Ile-Tyr, and Asp-Tyr-Gly-Leu-Tyr-Pro. By searching for the sequence homology in many proteins, four of them were found in the primary structure of actin. Asp-Met-Ile-Pro-Ala-Gln-Lys was obtained from the boiling water extract of dried bonito and this peptide was found in the primary structure of creatine kinase. Fragments of these peptides were prepared by further enzymatic digestion or chemical synthesis and their ACE-inhibitory activities were measured. Among them, Ile-Lys-Pro, Ile-Trp, Leu-Lys-Pro, and Leu-Tyr-Pro had higher inhibitory activity than their parental peptides. Ile-Lys-Pro suppressed the hypertensive activity of angiotensin I.
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PMID:Peptide inhibitors for angiotensin I-converting enzyme from thermolysin digest of dried bonito. 136 54

Ageing of the kidneys has long been associated with a fall in the number of functioning nephrons resulting in a reduction of renal blood flow and glomerular filtration. This narrow concept of age-related changes in renal function has been developed chiefly during the last few years by Brenner et al. on the basis of experimental studies conducted on rodents. According to these authors, the size and frequency of segmental and focal lesions of glomerulosclerosis increase regularly with age, and in its final phase this pathology results in occlusion of glomerular capillaries. Renal ageing, therefore, can be assimilated to the nephron reduction models obtained by surgical ablation. The hypothesis that hypofiltration in certain nephrons is compensated by hyperfiltration in healthy glomerulis, leading to a vicious circle of self-destruction, was then applied to both ageing and experimental renal impairment: the smaller the number of nephrons, the greater the filtration achieved by the remaining nephrons, a process that accelerates the probability of their destruction. Conversely, any attempt to reduce intracapillary pressure or glomerular filtration slows down the progression of renal failure. This hypothesis is supported by experiments showing that reduction of protein intake or chronic inhibition of angiotensin I-converting enzyme activity are truly capable of limiting the progression of glomerulosclerosis induced in rats by partial renal mass ablation. Similarly, prolonged food restriction increases the life expectancy of rodents and almost totally prevents the occurrence of glomerulosclerosis. The experimental finding that degenerative renal lesions do not necessarily develop with age raises the problem of normal and pathological ageing. With an adequate choice of rats' food, strain and sanitary surroundings it is possible to obtain very old animals devoid of occluded glomerular capillaries and loss of nephron. What about the functional and structural changes due to ageing and not to pathology? This question has given rise to numerous studies which concluded, on the whole, that there exists a normal ageing of the kidneys without loss of nephron and that ageing is expressed by the fact that the kidneys have difficulties in adjusting themselves to disturbances in the inner environment. As regards renal functional reserve, response to the antidiuretic hormone in case of water restriction, or stimulation of the renin-angiotensin system in response to decrease of sodium intake, it is clear that the renal cells responsible for glomerular filtration, tubular transport or synthesis and release of peptidic hormones exhibit functional alterations that are age-related. The cellular and molecular mechanisms underlying these physiological changes are little known.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Normal and pathological renal aging in animals]. 140 79

To evaluate the relationship between urinary albumin excretion and left ventricular hypertrophy in essential hypertension, we studied, cross-sectionally, 64 subjects with essential hypertension and no diabetes. Urinary albumin excretion and Sokolow index correlated significantly (r = 0.483; P = 0.0001). Five subjects were positive for microalbuminuria (> 30 mg/24 h) and Sokolow index (> 35 mm); 43 were negative for both, with a concordance rate of 77 percent (chi-squared test 11.1; P = 0.0009). Stepwise multivariate regression analysis indicated two independent determinants for urinary albumin excretion: Sokolow index (F = 18.29), and diastolic blood pressure (F = 12.23). The relationships between urinary albumin excretion, Sokolow index, and blood pressure were not different in the 18 subjects taking angiotensin I-converting enzyme inhibitors and in the 46 others. The close relationship between urinary albumin excretion and Sokolow index observed in this study suggests that left ventricular hypertrophy due to hypertension may account for the increased cardiovascular mortality observed in non diabetic subjects with microalbuminuria.
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PMID:[Microalbuminuria and left ventricular hypertrophy in essential arterial hypertension. A study in non-diabetic patients]. 143 89

To test the effect of converting enzyme inhibition (CEI) on diabetes, with or without renal insufficiency, we studied streptozotocin-induced diabetic rats, with or without reduced renal mass, which were treated with insulin in sufficient amounts to maintain glucose values in the mild to moderately hyperglycemic range. We found that diabetes increased glomerular filtration rate (GFR) (inulin clearance, 2.3 +/- 0.5 ml/min vs 1.9 +/- 0.1 ml/min; p < 0.05) and blood pressure (137 +/- 15 mm Hg vs 116 +/- 6 mm Hg; p < 0.05) but did not increase plasma atrial natriuretic peptide (ANP) values, when compared with control rats (72 +/- 38 vs 68 +/- 24 pg/ml). CEI decreased GFR and blood pressure to control values. In rats with diabetes and concomitantly reduced renal mass, hypertension, elevated ANP values, proteinuria, and glomerulosclerosis were prominent features. CEI was associated with reduced blood pressure (172 +/- 17 mm Hg vs 138 +/- 15 mm Hg; p < 0.05), without a concomitant decrease in GFR (1.1 +/- 0.1 ml/min vs 1.1 +/- 0.1 ml/min). Further, CEI reduced the elevated ANP values (140 +/- 34 pg/ml vs 66 +/- 19 pg/ml; p < 0.05) to those of control rats. CEI reduced proteinuria by 50% and ameliorated the histopathologic changes. In separate experiments, rats with 5/6th nephrectomy and hypertension but without diabetes were also found to have elevated ANP levels that decreased to control values with CEI. The data speak for a renal protective effect of angiotensin I-converting enzyme inhibition in this model but do not support a specific role for ANP in the model of diabetes with concomitantly reduced renal mass.
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PMID:Effects of angiotensin-converting enzyme inhibition in diabetic rats with reduced renal function. 145 98


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