Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Immunohistochemical techniques have been used to study a group of membrane peptidases in the distal segment of the ulnar nerve of piglets 7 and 14 days after surgical section. Five peptidases were studied, all of which have a wide distribution on the surfaces of many cell types and have roles in metabolising neuropeptides. In normal pig nerves, endopeptidase-24.11 is expressed by both myelin- and nonmyelin-forming Schwann cells. Peptidyl dipeptidase A (angiotensin converting enzyme), aminopeptidase-N and dipeptidyl peptidase IV are present in the microvessels, and aminopeptidase-N is also seen in the perineurial connective tissue. Of this group of peptidases, only aminopeptidase-W is a neuronal marker in normal nerve. Macrophages were identified by two antibodies, 74-22-15 and 40D (which recognises Ia). Short-term cultures of macrophages obtained by alveolar lavage were positively stained by both antibodies and about half of the cells also expressed aminopeptidase-N and dipeptidyl peptidase IV. Staining by 40D and 74-22-15 revealed the presence of significant numbers of macrophages in normal nerve, but none of the membrane peptidases colocalized with these cells. Seven days after section of the nerve, the distal segment showed morphological changes typical of Wallerian degeneration. Endopeptidase-24.11 was no longer visible in myelin sheaths, but remained a marker for the surface of Schwann cells (defined also by staining for glial fibrillary acidic protein). The macrophage markers revealed marked changes in the morphology of these cells, often consistent with their phagocytic activity. Two peptidases, aminopeptidase-N and aminopeptidase-W, also appeared at this time to be associated with cells exhibiting the morphology of activated macrophages. This association could be confirmed in many instances by double staining with 74-22-15 and antibodies to the peptidases. Angiotensin converting enzyme retained its single location in microvessels at 7 days after section, but at 14 days a new pattern emerged as it, too, was expressed by macrophages. Dipeptidyl peptidase IV was not shown to be a macrophage marker in the degenerating nerve. Thus Wallerian degeneration leads to remarkable changes in the cellular expression of membrane peptidase; endopeptidase-24.11 reflects the changed morphology of Schwann cells while aminopeptidase-N, aminopeptidase-W and angiotensin converting enzyme become expressed by the actively phagocytosing macrophages.
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PMID:Cellular reorganisation of membrane peptidases in Wallerian degeneration of pig peripheral nerve. 168 7

The time course of dipeptidase activity and the effect of p-mercuribenzoate (PCMB) on the subestimation of the fluorometric determination of angiotensin-converting enzyme (ACE, EC 3.4.15.1) during development was studied. ACE and dipeptidase activities were measured fluorometrically in homogenates of the developing chick retina using Hip-His-Leu and His-Leu as substrates, respectively, both either in the presence or in the absence of 1 mM PCMB. ACE activity was inhibited by captopril (IC50 1.7 nM), MK 422 (IC50 4.8 nM), BPP9a (IC50 0.25 microM) and BPP5a (IC50 1.2 microM), thus suggesting that avian retinal ACE catalytically resembles the mammalian enzyme. Dipeptidase activity varied 3.4-fold throughout development, leading to a large and variable (28-83%) subestimation of ACE activity during chick retina ontogenesis. PCMB (1 mM) inhibited 67-94% dipeptidase activity during development, thus greatly reducing any subestimation of ACE activity determination during the development of the chick retina.
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PMID:Effect of p-mercuribenzoate on the subestimation of angiotensin-converting enzyme measurement during chick retina development. 215 60

Bradykinin (BK) (Arg1-Pro2-Pro3-Gly4-Phe5-Ser6-Pro7-Phe8-Arg9) was degraded by rat brain synaptic membranes at a rate comparable to that found for Met-enkephalin, but approximately 40 times the rate for vasopressin and oxytocin. The catabolic pathway for BK and its metabolites was elucidated through the use of high performance liquid chromatography for metabolite identification and peptidase inhibitors for blocking specific cleavage sites. BK was hydrolyzed at three sites: at the -Phe5-Ser6- bond by metalloendopeptidase 24.15, at the -Pro7-Phe8- bond by an apparently novel peptidyl dipeptidase, and at the -Phe8-Arg9 bond by a carboxypeptidase B-like enzyme. Each enzyme contributed about equally to BK degradation under the assay conditions used. Some of the resulting metabolites were further hydrolyzed: BK(1-8) to BK(1-7) + Phe by a DFP inhibitable prolyl carboxypeptidase-like enzyme, BK(1-8) to BK(1-5) + BK(6-8) by metalloendopeptidase 24.15, BK(1-7) slowly to BK(1-5) by a second peptidyl dipeptidase which was captopril inhibited, and Phe-Arg to Phe + Arg by a bestatin-inhibited dipeptidase. A number of properties of the individual enzymes were determined including sensitivity to a variety of peptidase inhibitors. These results provide a starting point for investigating the potential physiological role of each enzyme in BK function in the brain.
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PMID:Degradation of bradykinin and its metabolites by rat brain synaptic membranes. 260 54

Endopeptidase-24.11 (sometimes referred to as 'enkephalinase') is a key cell-surface enzyme in the metabolism of neuropeptides. A previous immunohistochemical study mapped the enzyme in pig brain and indicated a striosomal ordering of the enzyme within the striatum. This point has now been confirmed by staining adjacent sections for acetylcholinesterase (by histochemistry) and endopeptidase-24.11 (by an immunoperoxidase method). While there were some general similarities in the mapping of these two hydrolases, e.g. in the caudate-putamen, globus pallidus, olfactory tubercle, substantia nigra and striatonigral tract, there were differences in intensity and in the microscopic distribution, e.g. as in striosomes for which acetylcholinesterase was diminished. Two other membrane peptidases, peptidyl dipeptidase A ('angiotensin converting enzyme') and aminopeptidase N, were also mapped by the same immunohistochemical method. Peptidyl dipeptidase A had some similarities with endopeptidase-24.11, e.g. in its concentration within the striatal nuclei, but clear differences were also apparent, in particular the absence of staining of the former in the globus pallidus and olfactory tubercle. Immunostaining for aminopeptidase N, in contrast to the other peptidases, was observed as a diffuse staining throughout the gray matter. At the microscopic level, two important differences were that staining for aminopeptidase N and peptidyl dipeptidase A was very intense throughout the vasculature of the brain and that striatal efferent bundles of unmyelinated fibres staining positively for endopeptidase-24.11 were depleted of the other two peptidases. All three peptidases were identified in the pia mater. Thus, endopeptidase-24.11, unlike peptidyl dipeptidase A and aminopeptidase N, is a marker for a set of striatal efferent fibres in pig brain.
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PMID:Endopeptidase-24.11 is striosomally ordered in pig brain and, in contrast to aminopeptidase N and peptidyl dipeptidase A ('angiotensin converting enzyme'), is a marker for a set of striatal efferent fibres. 290 57

We recently found and partially purified a new membrane-bound metallo dipeptidyl dipeptidase from bovine atrial tissue homogenates (Harris, R.B. & Wilson, I.B. (1984) Arch. Biochem. Biophys. 233, 667-675). We suggested that this enzyme was capable of cleaving the dipeptide, phenylalanyl-arginine from the C-terminus of atriopeptin II to give atriopeptin I. The atriopeptins are two atrial natriuretic peptides and the existence of the atrial peptide system has implicated the mammalian heart as an endocrine organ. The tetrapeptide benzoyl-glycyl-seryl-phenylalanyl-arginine was synthesized because it contains the C-terminal tripeptide sequence of atriopeptin II and should be useful to test the roles of the atrial enzyme and angiotensin I-converting enzyme in processing the atrial peptides. We found that for the atrial enzyme, Vmax was 13-fold higher and Km 7-fold-lower for this stand-in substrate than for benzoyl-glycyl-histidyl-leucine, a standard substrate used to measure converting enzyme activity. The ratio of Vmax/Km as a measure of substrate specificity indicates that the stand-in substrate is 86-fold better than benzoyl-glycyl-histidyl-leucine. In contrast, the stand-in substrate is a 20-fold poorer substrate for the converting enzyme than benzoyl-glycyl-histidyl-leucine. With the stand-in substrate, the converting enzyme showed pronounced substrate inhibition. An effective Vmax and Km were calculated using only concentrations of S below the optimum substrate concentration. These results confirm that the atrial enzyme is distinct from the converting enzyme. They also suggest that the conversion of atriopeptin II to atriopeptin I is a physiological process that is mediated by this enzyme.
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PMID:Comparison of hydrolysis of atriopeptin II stand-in substrate by atrial dipeptidyl carboxyhydrolase and angiotension I-converting enzyme. 299 58

Both endopeptidase-24.11 and peptidyl dipeptidase A have previously been shown to hydrolyse the neuropeptide substance P. The structurally related peptide neurokinin A is also shown to be hydrolysed by pig kidney endopeptidase-24.11. The identified products indicated hydrolysis at two sites, Ser5-Phe6 and Gly8-Leu9, consistent with the known specificity of the enzyme. The pattern of hydrolysis of neurokinin A by synaptic membranes prepared from pig striatum was similar to that observed with purified endopeptidase-24.11, and hydrolysis was substantially abolished by the selective inhibitor phosphoramidon. Peptidyl dipeptidase A purified from pig kidney was shown to hydrolyse substance P but not neurokinin A. It is concluded that endopeptidase-24.11 has the general capacity to hydrolyse and inactivate the family of tachykinin peptides, including substance P and neurokinin A.
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PMID:The metabolism of neuropeptides. Neurokinin A (substance K) is a substrate for endopeptidase-24.11 but not for peptidyl dipeptidase A (angiotensin-converting enzyme). 299 48

The circadian rhythms of lactase, sucrase and dipeptide hydrolase from homogenates of the small intestine mucose are unequal in different age. The amplitude of diurnal fluctuation is reduced in adult and, particularly, in old rats.
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PMID:[Circadian rhythmicity of the enzyme activity in the small intestine of growing, adult and old rats]. 311 97

Dipeptidase (dipeptide hydrolase [EC 3.4.13.11]) has been purified to homogeneity and crystallized from the cell extract of Bacillus stearothermophilus IFO 12983. The enzyme has a molecular weight of about 86,000, and is composed of two subunits identical in molecular weight (43,000). The enzyme contains 2 g atoms of zinc per mol of protein. A variety of dipeptides consisting of glycine or only L-amino acids serve as substrates of the enzyme; Km and Vmax values for L-valyl-L-alanine are 0.5 mM and 68.0 units/mg protein, respectively. The enzyme is significantly stable not only at high temperatures but also on treatment with protein denaturants such as urea and guanidine hydrochloride. The enzyme also catalyzes hydrolysis of several N-acylamino acids with Vmax values 3-30% of those for the hydrolysis of dipeptides. The thermostable dipeptidase shares various properties with bacterial aminoacylase [EC 3.5.1.14]: their subunit molecular weight, metal content and requirement, amino acid composition, and amino acid sequence in the N-terminal region are very similar.
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PMID:Thermostable dipeptidase from Bacillus stearothermophilus: its purification, characterization, and comparison with aminoacylase. 313 45

The circadian rhythms of maltase, alkaline phosphatase and dipeptide hydrolase were assessed in duodenum, proximal, medial and distal parts of the rat small intestine. Functional activities were assessed every 4 hrs for 24 hrs. Patterns of all enzymatic activities were different in different parts. The mucosal protein content in each segment of intestine was constant throughout the 24-hour period.
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PMID:[Circadian rhythmicity of the enzyme activity of different portions of the small intestine]. 353 11

In a study of changes in digestive enzymes after massive intestinal resection and the mechanisms by which such changes occur, rats were sacrified 4 wk after removal of the proximal two-thirds of the small intestine. Alterations in the mucosal levels of sucrase, enterokinase, and dipeptide hydrolase (L-leucyl-L-alanine substrate) were examined in the light of associated changes in protein. DNA and wet mucosal weight, measured in standardized gut segments from various regions of intestine. Metabolic studies showed that normal growth patterns were reestablished after the operation but significant elevations in stool weight and fecal nitrogen occurred in the second postoperative week, falling towards normal by the 4th wk. In standard gut segments wet weight of mucosa, protein, and DNA rose, especially in distal segments, DNA increasing disproportionately. Mucosal levels of the proximally distributed and membrane-bound enzymes, sucrase and enterokinase, showed similar patterns of change: when enzyme activity was expressed in terms of the total per segment, proximally there were considerable increases in both enzymes, but, expressed in terms of specific activity, that of sucrase fell and that of enterokinase was unaltered. By contrast, the largely soluble and more distally distributed dipeptide hydrolase increased more in distal segments and the increases in total activity were accompanied by lesser increases in specific activity. However, in spite of increases in total activity, enzyme activity per milligram DNA fell by over 50% in postanastomotic segments. Subcellular distribution studies showed no change in the percentage of the total activity which was membrane-bound and zymograms confirmed that no new dipeptide hydrolase had appeared after resection. It is concluded that increases in the segmental totals of various enzymes seen after resection are achieved by disproportinate increases in the number of mucosal cells per segment and that the greatest change in a particular enzyme occurs in the region where the enzyme is normally found in highest concentration.
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PMID:Changes in sucrase, enterokinase, and peptide hydrolase after intestinal resection. The association of cellular hyperplasia and adaptation. 469 57


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