SEARCH · PubMed Health

Results for “AMINOPEPTIDASES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34Linked to original sources

PubMed1975

Aminopeptidases and arylamidases in normal and cancer tissues in humans.

Multiforms of aminopeptidases and arylamidases in normal human liver, stomach, lung, ileum, colon, rectum, and kidney, and cancer tissue from human liver, stomach, and lung were separated by triethylaminoethyl cellulose column chromatography. The aminopeptidases and arylamidases were solubilized from human tissues by treatment with bromelain, and their column chromatograms on triethylaminoethyl-cellulose gave different patterns of multiforms of enzymes in these tissues. The fractions of enzymes separated specificities toward L-leucyl-beta-naphthylamide, L-leucinamide, L-methioninamide, L-phenylalaninamide, and L-alaninamide. The activity of aminopeptidase toward L-leucinamide and of arylamidase toward L-leucyl-beta-naphthylamide was higher in human stomach cancer tissue and lower in hepatic cancer tissue than in normal stomach and liver, respectively. In lung cancer tissue, the activity of aminopeptidase toward L-leucinamide was abnormally low, while the activity of arylamidase toward L-leucyl-beta-napthylamide was similar to that in normal lung. The substrate specificities or patterns of the multiforms of these enzymes in cancer tissue from human liver, stomach, and lung were shown to differ from those of normal liver, stomach, and lung, respectively, by triethylaminoethyl cellulose column chromatography.

Alanine↗

PubMedDate not supplied

[Influence of alcohol on brain aminopeptidases. An in vitro study].

INTRODUCTION: It is well known the depressor effect of alcohol on several inhibitory nervous centres. This can be due to the inhibition that induces in the release of different type of neurotransmitters, and because alcohol can increase the membrane fluidity and changes the function of proteins inserted in the membrane. Several aminopeptidases (AP) have been described as enzymes that regulate the activity of peptide neurotransmitters. In the present work, the influence of alcohol (25, 50 and 100 mM) on several aminopeptidase activities (alanyl AP, arginyl AP, cystinyl AP, leucyl AP and tyrosyl AP) has been determined in synaptosomes obtained from the cortex of mouse, under basal and K+ stimulated conditions and their calcium dependence, in a non toxic in vitro model. MATERIAL AND METHODS: AP activities were determined using aminoacyl ? naphthylamides as substrates. Non toxic in vitro model were demonstrated analyzing free radical generation, lipid peroxidation and oxidation of synaptosomal proteins. In addition, the bioenergetic behavior of synaptosomes was determined under different experimental protocols. RESULTS: In basal conditions, alcohol produces a dose related inhibition of alanyl AP activity. The rest of activities show a biphasic behavior. In this way, depending on the concentration of alcohol used, aminopeptidases are inhibited or stimulated. Depolarization with K+ 25 mM leads to a decrease of alanyl AP and tyrosyl AP activities but does not change the rest of activities. The presence of alcohol under stimulated conditions produces the inhibition of all the enzymatic activities, specially with the highest concentrations used. CONCLUSIONS: Alcohol modifies several aminopeptidase activities from synaptosomes of the cortex of mouse, acting in different ways under basal or stimulated conditions. These effects seem not to be related with degenerative events induced by alcohol. Therefore, a specific effect of this substance on the neurotransmisory/neuromodulatory systems mediated by neuropeptides must exist, modifying the enzymes that are responsible of their degradation.

Aminopeptidases↗

PubMed1975

[Urinary alanine aminopeptidase and lysozyme excretion in patients with diabetes].

The excretion of alanine aminopeptidase in the urine is changed by several factors influencing the tubuli. The diabetics increasedly excrete alanine aminopeptidase in the urine, apparantly as an expression of an increased cell moulting of the tubuli. Whether the increased alanine aminopeptidase activity of the urine may indicate a diabetic nephropathy, is to be clarified only by means of bioptic investigations of the kidneys. Streptomycin can also like a nephrostasis as a sequel of a decompensated cor pulmonale increase the activity of alanine aminopeptidase of the urine.

Aminopeptidases↗

PubMed2003

Aminopeptidase activity in renovascular hypertension.

BACKGROUND: Renovascular hypertension is accompanied by increased renin-angiotensin system activity. Angiotensin II (Ang II) is degraded by aminopeptidases into various metabolites. Increased Ang II production and decreased Ang II degradation may have pathological consequences in maintaining high tissue/plasma Ang II levels. MATERIAL/METHODS: We report the effects of renovascular hypertension on alanyl- (AlaAP), arginyl- (ArgAP), cystinyl- (CysAP), aspartyl- (AspAP), glutamyl- (GluAP) and pyroglutamyl- (pGluAP) aminopeptidases, using arylamides as substrates. The enzymatic activities were analyzed in plasma, right atrium, lung, left ventricle and aortic ring of rats, normotensive (sham-operated) and hypertensive (Goldblatt two-kidney one-clip, G2K1C), treated or not with the AT1 receptor antagonist valsartan. All determinations were performed six weeks after surgery. RESULTS: Whereas the atrium exhibited an increase, the lung, ventricle and aorta showed a decrease of aminopeptidases in G2K1C rats. Except in the aorta of normotensive rats, valsartan did not affect aminopeptidases in the groups studied. CONCLUSIONS: The present study may imply reduced metabolism of angiotensin II in the lung and aorta of G2K1C rats. This down-regulation could prolong the half-life of Ang II and contribute to the maintenance of hypertension. Changes in AP activities did not appear to be part of the action mechanism of AT1 receptor blockade in hypertensive rats

Aminopeptidases↗

PubMed1992

[Regional distribution of brain aminopeptidases in the rat].

Soluble and membrane-bound aminopeptidase activities in eleven regions of the rat brain were assayed using L-leucine-2-naphthylamide as a substrate. In addition, two metabolic enzymatic activities were compared: lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotransferase activities were significantly lower in cortical than in subcortical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did no differ between cortical areas and the rest of the zones studied. However, while no wide regional differences were found for the other enzymatic activities, membrane-bound aminopeptidase varied markedly across brain regions: a 5-fold difference was observed between zones. The differential distribution of this enzymatic activity is consistent with the hypothesis that it is responsible for the enzymatic inactivation of some neuroactive peptides.

Aminopeptidases↗

PubMed1992

Isolation of the leucine aminopeptidase gene from Aeromonas proteolytica. Evidence for an enzyme precursor.

The leucine aminopeptidase of Aeromonas proteolytica (EC 3.4.11.10) is a monomeric metalloenzyme having the capacity to bind two Zn2+ atoms in the active site. Structural information of this relatively small aminopeptidase that could illuminate the catalytic mechanism of the metal ions is lacking; hence, we have obtained sequences from the purified enzyme, cloned the corresponding gene, and expressed the recombinant protein in Escherichia coli. The deduced primary amino acid sequence of this secreted protease suggests a potential signal peptide at the NH2 terminus. Expression of the recombinant and native proteins in E. coli and in extracts of culture media of A. proteolytica indicates that the aminopeptidase is secreted as an active and thermosensitive 43-kDa protein that is rapidly transformed to thermostable forms of 30 and 32 kDa. Comparison of the deduced amino acid sequence of the A. proteolytica leucine aminopeptidase with other Zn(2+)-binding metalloenzymes failed to show homologies to the consensus binding sequence His-Glu-X-X-His for the metal ion.

Aeromonas↗

PubMed1990

Serum and brain aminopeptidase activities in cyclic rats.

Research into the functional role of brain peptides is performed, in part, by studying peptidase enzymes which might be involved in the processing or inactivation of the brain peptides. Aminopeptidase activity has been proposed as a candidate for the regulation of the degradation of these peptides. In this paper, acid (Asp-) and basic (Arg-) aminopeptidase activities were studied in several brain regions and in the serum during the estrous cycle of the rat. Asp-aminopeptidase activity did not significantly change at any point. However, a marked rise was found in Arg-aminopeptidase activity in all the brain areas studied and the serum during the proestrus. It is suggested that this activity plays a role in the hormonal changes that take place during the cycle, possibly in regulating the activity of several neuroactive peptides.

Aminopeptidases↗

PubMed1975

[Study of the enzyme activity of serum cystine aminopeptidase in man and animals in relation to the pH of the medium].

The authors studied the splitting dynamics of the synthetic chromogenic substrate (S-benzyl-L-cysteine-p-nitroanilide) specific of serum cystine aminopeptidase, depending on a wide range of pH (from 2.5 to 8.0) by means of an enzymatic serum system of pregnant women and selected animals (sheep, cows, sewer-rats), compared with non-pregnant controls. Examining the form of the enzymatic activity curves of the enzymatic system of women's and animal serum in dependence on pH, the authors revealed a characteristic bell-shaped course of the curve in the serum of pregnant women, as distinct from the sera of animals; the activity of cystine aminopeptidase in cows shows a two-peak course at pH from 3.5 to 4.0 and at pH from 6.5 to 7.0 while other animal species show irregularities with signs of the second peak. It follows from the results of the experiment that the main difference between pregnant and control animals is not the general increase of cystine aminopeptidase but a shift of the occurrence, or an increase of enzymatic activity at the given pH. The highest levels of cystine aminopeptidase were found in the blood sera of sewer-rats and lower in sheep and cows.

Aminopeptidases↗

PubMed1989

Organelles involved in the intracellular transport of newly synthesized aminopeptidase N and their acidity.

The intracellular routes taken by aminopeptidase N, an apically expressed enzyme in the enterocyte, was followed in small intestinal cultures of pig using either immunoelectron microscopy (immunogold labeling) or continuous labeling with [35S]methionine. Aminopeptidase N was found in the microvillar membrane, the Golgi complex, apical small smooth vesicles, and various acidic lysosomal/endosomal-like organelles. By culturing mucosal explants in the presence of either cycloheximide or (3-(2,4-dinitroanilino)-3-amino-N-methylpropylamine) (DAMP) it was demonstrated that the apical small smooth vesicles are exocytotic and that the low pH in the acid compartments is of no importance for intracellular transport and correct sorting of aminopeptidase N. Furthermore, our results show that the majority of the aminopeptidase N in the lysosomal/endosomal-like compartments is newly synthesized.

Aminopeptidases↗

PubMed1989

Molecular cloning and sequencing of genomic DNA encoding aminopeptidase I from Saccharomyces cerevisiae.

Yeast aminopeptidase I is a vacuolar enzyme, which catalyzes the removal of amino acids from the NH2 terminus of peptides and proteins (Frey, J., and Rohm, K-H. (1978) Biochim. Biophys. Acta 527, 31-41). A yeast genomic DNA encoding aminopeptidase I was cloned from a yeast EMBL3A library and sequenced. The DNA sequence encodes a precursor protein containing 514 amino acid residues. The "mature" protein, whose NH2-terminal sequence was confirmed by automated Edman degradation, consists, based only on the DNA sequence, of 469 amino acids. A 45-residue presequence contains positively and negatively charged as well as hydrophobic residues, and its NH2-terminal residues could be arrayed in an amphiphilic alpha-helix. This presequence differs from the signal sequences which direct proteins across bacterial plasma membranes and endoplasmic reticulum or into mitochondria. It remains to be established how this unique presequence targets aminopeptidase I to yeast vacuoles and how this sorting utilizes classical protein secretory pathways. Further, the aminopeptidase I gene, localized previously by genetic mapping to yeast chromosome XI and called the LAP4 gene (Trumbly, R. J., and Bradley, G. (1983) J. Bacteriol. 156, 36-48), was determined by DNA blot analyses to be a single copy gene located on chromosome XI.

Amino Acid Sequence↗

PubMed1986

Diagnostic significance of some urinary enzymes for detecting acute rejection crises in renal-transplant recipients: alanine aminopeptidase, alkaline phosphatase, gamma-glutamyltransferase, N-acetyl-beta-D-glucosaminidase, and lysozyme.

We compared the diagnostic validity of five urinary enzymes--alanine aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30), and lysozyme (EC 3.2.1.17)--as indicators of acute rejection crises in renal-transplant recipients. In 82 patients (group A), the excretion of each of these five enzymes was measured daily from transplantation until discharge from hospital. In another 69 patients (group B), enzyme determinations were made when the patient came for regular checkups (about every four to eight weeks). We used an "activity ratio" (the activity measured at a particular time compared with the activity on the preceding determination) value of 1.5 as the decision point. In group A, use of this discrimination point for alanine aminopeptidase, gamma-glutamyltransferase, and N-acetyl-beta-D-glucosaminidase yielded a specificity and sensitivity of about 90%. In group B, only alanine aminopeptidase had a greater diagnostic sensitivity than creatinine alone. Evidently, measurement of alanine aminopeptidase can be a helpful indicator of acute rejection crises, when interpreted in combination with other available relevant clinical, biochemical, and immunological data.

Acetylglucosaminidase↗

PubMed1987

Biosynthesis of intestinal microvillar proteins. Forskolin reduces surface expression of aminopeptidase N.

The effect of forskolin on the biosynthesis and intracellular transport of pig intestinal aminopeptidase N (EC 3.4.11.2) was studied in organ cultured mucosal explants. The drug which activates adenylate cyclase and hence the cAMP-dependent glycogenolytic pathway did not affect the explant content nor microvillar enrichment of the enzyme. Forskolin, however, caused a decrease in the microvillar expression of aminopeptidase N which developed in a time-dependent manner from about 40% by 80 min to 80% by 4 h of labeling. The intracellular pool size of the transient, high mannose glycosylated form of aminopeptidase N was unaffected by forskolin, indicating a normal synthesis in the rough endoplasmic reticulum. The decrease in surface expression is therefore caused by an induced posttranslational degradation of the enzyme, most likely taking place in the Golgi complex. The degradatory effect on newly synthesized aminopeptidase N was not accompanied by any morphological alterations of the enterocyte; in particular, the microvillar membrane appeared entirely unaffected by forskolin. The results obtained provide evidence for the existence of a posttranslational mechanism, whereby a polarized cell is capable of regulating its expression of apical proteins.

Aminopeptidases↗

PubMed1986

Isolation and characterization of a new aminopeptidase from bovine lens.

An aminopeptidase has been purified to homogeneity from bovine lens tissue by gel filtration and DEAE-cellulose chromatography. This enzyme has a molecular weight of 96,000 under both native and denaturing conditions. The purified enzyme hydrolyzed a variety of synthetic substrates as well as di-, tri-, and higher molecular weight peptides. Significantly this enzyme is capable of hydrolyzing arginine, lysine, and proline aminoacyl bonds. The pH optimum for activity and stability was 6.0. Both a reduced sulfhydryl group and a divalent metal ion are essential for activity. The native enzyme contains 1.6 mol of zinc and 1.0 mol of copper/mol of enzyme. No activation was seen upon incubation with either magnesium or manganese; however, heavy metal ions were inhibitory. Bestatin and puromycin were effective inhibitors and no endopeptidase activity could be detected in the purified preparation. This enzyme is clearly distinct from the lens leucine aminopeptidase, but rather, is identical to a cytosolic aminopeptidase III isolated from other tissues. Evidence is presented which argues that this enzyme may be the major lens aminopeptidase under in vivo conditions.

Aminopeptidases↗

PubMed1988

Proline aminopeptidase activity as a rapid diagnostic test to confirm bacterial vaginosis.

Two biochemical indicators of bacterial vaginosis, proline aminopeptidase activity and gas-liquid chromatographic analysis, were compared. Five hundred women had their vaginal secretions tested for pH, presence of a positive amine test, levels of volatile and nonvolatile short-chain organic acids, and proline aminopeptidase activity. In addition, direct microscopic and Gram stain examinations were performed. Of the 500 women, 349 (70%) had some form of vaginitis. One hundred sixteen were diagnosed as having bacterial vaginosis, and 69 of these (59%) had Mobiluncus sp on either direct microscopic or Gram stain examination. Two hundred thirty-three had either mixed or other forms of vaginitis. One hundred fifty-one patients were normal. The sensitivity of the proline aminopeptidase assay was 83 and 79%, respectively, in patients having bacterial vaginosis with and without Mobiluncus morphotypes. In contrast, gas-liquid chromatography of short-chain organic acids had sensitivities of 71 and 30%, respectively. Specificity of both assays was about 95%. The greater sensitivity of the proline aminopeptidase assay, especially in patients without Mobiluncus morphotypes, proves its superiority.

Aminopeptidases↗

PubMed1987

Binding, degradation and pressor activity of angiotensins II and III after aminopeptidase inhibition with amastatin and bestatin.

In the metabolism of angiotensin peptides by tissue angiotensinases, aminopeptidases A, B, M and leucine aminopeptidase have been identified as being particularly effective. Because the inhibitory actions of amastatin (AM) and bestatin (BE) are relatively specific for these aminopeptidases, we have examined the effects of these inhibitors on the binding, degradation and pressor activity of angiotensin II (AII) and angiotensin III (AIII). Within 30 min at 37 degrees C, significant metabolism of 125I-AII and 125I-AIII by homogenates of a block of tissue containing hypothalamus, thalamus, septum and anteroventral third ventricle regions of the brain was observed. A majority of 125I-AIII metabolism was due to soluble peptidases, whereas that of 125I-AII primarily resulted from membrane-bound peptidases. AM, BE and reduced incubation temperatures significantly decreased the metabolism of 125I-AII and 125I-AIII. After appropriate adjustments to reflect the proportion of intact radioligand bound, temperature- or inhibitor-induced decreases in metabolism were matched by corresponding increases in specific binding. Heat-treated bovine serum albumin, as a nonspecific peptidase inhibitor, had no effect on either the metabolism or binding of the ligands used. In accordance with their actions in vitro, i.c.v. administration of AM and BE prolonged the pressor activity of subsequently applied AII and AIII. Unexpectedly, the amplitude of the pressor response to AIII was increased by BE, whereas that to AII was decreased by AM. The results of this study indicate that the metabolism of AII and AIII by aminopeptidases is relatively specific and acts to modulate the actions of these peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopeptidases↗

PubMed1979

[Serum activity of leucine aminopeptidase in lymphotropic infections and in malignant lymphomas].

Increases of the leucine aminopeptidase according to data of literature are regarded as a sensitive parameter of lesions in liver diseases. In patients with active generalised lymphadenitis (viral infections, toxoplasmosis) as a typical enzyme constellation a relatively strong leucine aminopeptidase increase in the serum with missing or relatively slight enzyme deviation of the transaminases could be found. The quotient of the activities of LAP/ALAT was clearly above that of inflammatory liver diseases. In chronic lymphatic leukosis, plasmocytoma and malignant lymphomas the leucine aminopeptidase serum activities were within the normal. Increases of leucine aminopeptidase in lymphotropic infections are probably partly of extrahepatic origin.

Humans↗

PubMed1980

[Determination of alanine aminopeptidase and lactate dehydrogenase in the urine as a control over the patient's course after kidney transplantation].

In 42 patients the determination of alanine aminopeptidase and lactate dehydrogenase in the urine was performed after transplantation of a kidney. In the evaluation of the enzyme activities it was referred to the clinically made rejection diagnosis as well as to the increase of the serum creatinine. We found out that with regard to the clinically made rejection diagnosis the alanine aminopeptidase in 56% and the lactate dehydrogenase in 55% of the cases showed an increase before the beginning of the rejection therapy. Before the corresponding increase of the serum creatinine we could establish an increase of the enzyme activity in the alanine aminopeptidase in 45% and in the lactate dehydrogenase in 65% of the cases. For a better interpretation of the urinary enzyme activities during the rejection crises the average activities of the enzymes immediately after the dismissal of the patients as well as three months, six months and one year after the transplantation are cited. From our investigation results that the daily determination of alanine aminopeptidase and lactate dehydrogenase in the urine is suited, taking into consideration other possible influence factors on the enzyme activity as well as other parameters, to support the diagnostics in finding the rejection after the transplantation of a kidney.

Aminopeptidases↗

PubMed1984

A family with a high serum aminopeptidase (microsomal) activity: properties of the enzyme from serum of the propositus.

We found a family with a high activity for hydrolyzing L-alanyl-beta-naphthylamide in their serum. This enzyme was confirmed to be aminopeptidase (microsomal) (EC 3.4.11.2) by means of immunological experiments involving anti-human kidney aminopeptidase (microsomal) antibody. We could not find the cause of the increased activity from the results of clinical and laboratory examinations. The enzyme from the propositus resembled that from the serum of normal subjects in molecular mass (240 000 Da), Km value (87 mumol/L), and degree of inhibition by antiserum to human kidney aminopeptidase (microsomal). It differed from the normal enzyme with respect to electrophoretic mobility (R1 value, 0.58; normal, 0.51), isoelectric point (pI, pH 3.4; normal, pH 3.8), and heat stability (more labile than normal). From information on this family and another one reported in the Japanese literature, we suggest that the mode of inheritance of a high activity of serum aminopeptidase (microsomal) may be autosomal dominant.

Adolescent↗