PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “LEUCINE AMINOPEPTIDASE”

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 55 records · Page 3Linked to original sources
PubMed1976

Urinary leucine aminopeptidase in bilharziasis.

Leucine aminopeptidase activity and total protein concentration was estimated in the fresh early morning sample of urine of twenty five normal adult subjects, twenty four cases with active urinary bilharziasis, eleven cases with active intestinal bilharziasis, ten cases with mixed bilharzial infection (urinary and intestinal), fourteen bilharzial cases with clinical hepatosplenomegaly of bilharzial etiology, thirteen bilharzial cases with clinical hepatosplenomegaly and ascites, and twelve cases with cancer bladder of bilharzial etiology. It was found that there is a significant increase in LAP activity in the urine of all groups of patients studied. Again this increase ran parallel to the course of the disease in bilharzial cases. Urine protein concentration was found to be increased significantly in all groups of bilharzial cases studied with the highest value in urine of patients with cancer bladder of bilharzial etiology. However no direct correlation was found between urinary LAP level and protein concentration either within the individual cases or within the different groups.

Adult↗
PubMedDate not supplied

Seminal plasma leucine aminopeptidase in male fertility.

Leucine aminopeptidase (LAP) enzymatic activity has been measured in the seminal fluid of a group of 119 males undergoing fertility check-up, and correlated with spermatic density. The results indicate that there exists a direct correlation between LAP activity in the seminal plasma and spermatic density. However, differences between the groups considered according to spermatic density are not significant. Seminal plasma mean leucine aminopeptidase is 40 times higher than that found in blood plasma.

Fertility↗
PubMed1982

Electrophoretic types of leucine aminopeptidase in sheep serum.

Leucine aminopeptidase in sheep serum was studied by starch gel electrophoresis. Two phenotypes, A and B, were observed, of which the former was present in 70-90% of all the sheep examined. These two phenotypes have been shown to be controlled by a single autosomal locus, with two alleles LapA and LapB. The LapA allele is dominant. The frequencies of Lap phenotypes and alleles were determined in eleven Spanish and two foreign breeds. Serum alkaline phosphatase and serum leucine aminopeptidase are electrophoretically distinct.

Alkaline Phosphatase↗
PubMed2001

Functional analysis of leucine aminopeptidase in Caenorhabditis elegans.

To investigate the function of the enzyme leucine aminopeptidase in nematodes, a Caenorhabditis elegans leucine aminopeptidase gene identified in the genome sequence was functionally analysed by transfection of a leucine aminopeptidase beta-galactosidase reporter construct and characterisation of a null mutant. The leucine aminopeptidase transgene is expressed along the length of the gut, and immunolocalisation shows the enzyme in the buccal cavity, pharynx, anterior gut and rectum. It is constitutively expressed as seen by analysis of cDNAs constructed from mRNAs of nematodes taken at 2 h intervals through the life-cycle; and by western blot analysis of protein from the same set of nematodes. Leucine aminopeptidase null mutants had a slower growth rate and delayed onset of egg-laying. We suggest that in C. elegans, leucine aminopeptidase is a digestive enzyme.

Amino Acid Sequence↗
PubMed2001

Genomic organization of the human adipocyte-derived leucine aminopeptidase gene and its relationship to the placental leucine aminopeptidase/oxytocinase gene.

The genomic organization of the gene encoding the human adipocyte-derived leucine aminopeptidase (A-LAP) has been determined. The gene is composed of 20 exons and 19 introns and spans approximately 47 kilobases of chromosome 5q15. The gluzincin aminopeptidase motif, the HEXXH(X)(18)E zinc-binding motif essential for enzymatic activity, is encoded by exons 6 and 7. A comparison of the exon/intron boundaries, together with phylogenetic analysis, shows the close relationship between A-LAP and placental leucine aminopeptidase (P-LAP)/oxytocinase, another gluzincin aminopeptidase considered to be important for the maintenance of normal pregnancy. Primer extension analysis revealed two transcriptional initiation sites. Analysis of the sequence immediately upstream of the transcriptional initiation sites revealed that the A-LAP promoter contains no canonical TATA- or CCAAT-box, but has a PyPyA(+1)N(T/A)PyPy initiator consensus sequence and multiple putative regulatory elements. Finally, luciferase-reporter assays revealed a functional promoter activity of the 5'-flanking region of the gene, and suggested that the activity is regulated in a cell type-specific manner.

Adipocytes↗
PubMed1977

[Isolation and properties of leucine aminopeptidase from Aspergillus oryzae].

Homogenious leucine aminopeptidase is purified from "oryzine"--mixture of enzymes produced by surface culture of Asperigillus oryzae using treatment with activated characoal, followed by DEAE-cellulose and hydroxylapatite chromatographies, Biogel P-100 gel-filtration and polyacrylamide-gel electrophoresis. The enzyme has pH optimum 9.0 and the molecular weight 37500 as estimated by gil-filtration through Sephadex G-100 (superfine) and SDS-polyacrylamide gel electrophoresis. Leucine aminopeptidase from Asp. oryzae has a broad substrate specificity, therefore, cleaving with the highest rate the peptides carrying N-terminal leucine. The enzyme is completely inhibited with EDTA and beta-mercaptoethanol, and it is a metalloenzyme.

Aspergillus↗
PubMed1981

Purification and enzymatic properties of an L-leucine aminopeptidase from swine liver.

An L-leucine aminopeptidase (alpha-aminoacyl-peptide hydrolase (cytosol), EC 3.4.11.1), having a specificity toward the substrate L-leucine amide, but not toward L-leucyl beta-naphthylamide or L-leucyl p-nitroanilide, has been purified 332-fold from swine liver, with a yield of 8.6%. This is the first purification of this enzyme from hepatic tissue. The purified enzyme submitted to analytical electrophoresis on cellulose acetate strips or in polyacrylamide gel showed a single band after straining with Ponceau S Red dye or Amido black, respectively. Purified swine liver L-leucine aminopeptidase, a cytosol enzyme, exhibited a molecular weight of 268 000 +/- 50 000 by gel filtration. It hydrolyzed L-leucine amide substrate and L-leucyl peptides. It was activated by Mg2+ and Mn2+ and inhibited by Co2+ and Zn2+. The optimum pH was 10. It was rather sensitive to heat elevation. Swine liver L-leucine aminopeptidase was inhibited by EDTA, citric acid, isocaproic acid, dodecylamine, aliphatic alcohols and p-chloromercuribenzoate but unaffected by monoiodoacetic acid and diisopropyl fluorophosphate.

Animals↗
PubMed1985

Use of secondary isotope effects and varying pH to investigate the mode of binding of inhibitory amino aldehydes by leucine aminopeptidase.

Ki values for leucine aldehyde, a competitive inhibitor of leucine aminopeptidase, vary with pH in a manner compatible with binding of uncharged inhibitor. The pH dependence of kcat/Km suggests likewise that the substrate leucine p-nitroanilide is productively bound as the uncharged species. Comparison of pKa values of the model compounds aminoacetone and aminoacetal indicates that the equilibrium constant for hydration of amino aldehydes is reduced by a factor of about 2 when a proton is lost from the alpha-ammonium group near pH 8. Effects of deuterium substitution at C-1 on equilibrium binding of leucine aldehyde were determined with immobilized enzyme and inhibitors doubly labeled with radioisotopes. The observed isotope effect (KD/KH) is approximately unity, suggesting that leucine aldehyde combines with the enzyme as an oxygen adduct, not as the intact aldehyde.

Deuterium↗
PubMed1984

Comparative studies on the leucine aminopeptidase activity of different types of leukocytes.

The distribution of the leucine aminopeptidase activity among different types of leukocytes in a few animals was examined. In guinea-pig, the enzyme activity was detected in all cell types examined but its activity per cell was diverse among leukocytes, i.e. neutrophils and monocyte-macrophage cell lines, so-called "professional" phagocytes, showed higher enzyme activity than other types of leukocytes, lymphocytes and eosinophils. The same distribution pattern of leucine aminopeptidase activity as that in guinea-pig was also observed among leukocytes in human, rat and mouse. When leukocytes were modified with a poorly permeant reagent, diazotized sulfanilic acid to examine the subcellular localization of leucine aminopeptidase in leukocytes, the leucine aminopeptidase activity of the cells was inhibited by 50% without the inhibition of lactate dehydrogenase, a soluble cytoplasmic enzyme, in various types of leukocytes from all animals used here. The possibility was suggested from these observations that higher leucine aminopeptidase activity is distributed on the cell surface of "professional" phagocytes.

Animals↗
PubMed2002

Leucine aminopeptidase during meiotic development.

We found a leucine aminopeptidase (LAP; EC 3.4.11.1) to be abundant in meiotic prophase tissue of a basidiomycete, Coprinus cinereus. After direct purification of the aminopeptidase component from meiocytes, we cloned the gene by degenerate PCR using partial amino-acid sequences of the purified enzyme and 5' and 3' RACE. It was homologous to the eukaryotic leucine aminopeptidase gene. The recombinant protein possesses the characteristic activities of a Coprinus leucine aminopeptidase (CoLAP) with a molecular mass of 52.4 kDa, and forms a homohexamer. Northern blot and spatial distribution analysis by immunohistochemical staining indicated CoLAP to be abundant in meiotic prophase cells and the supporting cells around meiocytes, but scarce in mycelium cells. Interestingly, from zygotene to pachytene, CoLAP was mostly present in supporting cells around meiocytes, but from diplotene onwards, it was plentiful in meiocytes themselves, suggesting that its expression is required to control some of the biochemical events at meiotic prophase. Moreover, the strong expression of CoLAP mRNA immediately after treatment with methyl methanesulfonate in mycelium implies that CoLAP has a role in somatic DNA repair.

Amino Acid Sequence↗
PubMed1992

Leucine aminopeptidase from Arabidopsis thaliana. Molecular evidence for a phylogenetically conserved enzyme of protein turnover in higher plants.

Leucine aminopeptidases are exopeptidases which are presumably involved in the processing and regular turnover of intracellular proteins; however, their precise function in cellular metabolism remains to be established. Towards this goal, a full-length complementary DNA encoding a plant leucine aminopeptidase was isolated from a cDNA library of Arabidopsis thaliana and sequenced. The nucleotide sequence showed 49.5% identity to the Escherichia coli xerB-encoded leucine aminopeptidase. Sequence analysis revealed that the cDNA encodes a polypeptide of 520 amino acids with a calculated molecular mass of 54,506 Da. The C-terminal part (amino acids 200-520) of the deduced amino acid sequence showed 43.8% sequence identity to the xerB-encoded leucine aminopeptidase and 42.6% sequence identity to the amino acid sequence of bovine lens leucine aminopeptidase (EC 3.4.11.1). No sequence similarity (not even over short sequence elements) was observed with any other known peptidase or proteinase sequence. The cDNA was expressed as a fusion protein from the lacZ promoter in E. coli. Enzymatic analysis proved that the cloned cDNA encoded an active leucine aminopeptidase. The properties of this enzyme, including metal requirements, inhibitor sensitivity, pH optimum and the remarkable temperature stability, are very similar to those reported for leucine aminopeptidases from other tissues. Amino acids involved in metal and substrate binding in bovine lens aminopeptidase are completely conserved in the plant enzyme as well as in the XerB protein. Our results show that leucine aminopeptidases form a superfamily of highly conserved enzymes, spanning the evolutionary period from the bacteria to animals and higher plants. This is the first aminopeptidase cloned from a plant.

Amino Acid Sequence↗
PubMed1982

alpha-aminoaldehydes: transition state analogue inhibitors of leucine aminopeptidase.

L-Leucinal, prepared by enzymatic oxidation of L-leucinol with alcohol dehydrogenase, is found to be a very strong competitive inhibitor of porcine kidney aminopeptidases. For the enzyme from kidney microsomes acting on L-leucine p-nitroanilide (Km = 5.2 x 10(-4) M), for Ki for L-leucinal was 7.6 x 10(-7) M at pH 7.2 and 25 degrees C. For the enzyme from kidney cytosol acting on L-leucine p-nitroanilide (Km = 7.7 x 10(-4) M), Ki for L-leucinal was 6 x 10(-8) M; Ki for glycinal (analogous to glycine derivatives that are poor substrates) was 6.8 x 10(-4) M. In dilute aqueous solution, leucinal exists in unfavorable equilibrium with its covalent hydrate, whose concentration exceeds that of the free aldehyde by a factor of 40. The affinity of the enzyme for the free aldehyde is correspondingly greater than its Ki values would suggest, exceeding the apparent affinity of the substrate by a factor of about 10(6). A comparison of binding affinities suggests that L-leucinal forms an inhibitory complex analogous in structure to unstable intermediates and substrate transformation by leucine aminopeptidase, and strengthens the likelihood that this enzyme may act by a double-displacement mechanism.

Anilides↗
PubMed1981

Aminopeptidases in seeds of picea abies (L.) Karst.: characterization of leucine aminopeptidase by molecular properties and inhibitors.

By either acrylamide or starch gel electrophoresis of Norway spruce (Picea abies) seed extracts, two prominent isoenzyme bands were obtained after staining for leucine aminopeptidase (LAP). These bands were proved to correspond to each other by reelectrophoresis in both gel media. Single endosperm studies with acrylamide gels showed clearly that, in addition to LAP, two bands are expressed after staining for alanine aminopeptidase (AAP) as well. Both the LAP and the AAP activities appeared together as a single peak between catalase and ferritin after gel chromatograhy on Sepharose. Isoelectric focusing in sucrose gradients proved the two LAP activities to have identical isoelectric points revealed that LAP, but not AAP, is detectable by standard starch gel electrophoretic procedures. The two LAP bands refer to approximate molecular weights of 71,000 and 131,000, respectively. Disaggregation studies did not conclusively determine whether these two bands represent different enzymes or not. only inhibitors succeeded in producing a definite differentiation by selective inhibition of one of the two bands. It is concluded that in both gel media the isoenzyme bands reflect the activity of two distinct leucine aminopeptidases.

Aminopeptidases↗
PubMed1989

Leucine aminopeptidase M-induced reductions in blood pressure in spontaneously hypertensive rats.

Leucine aminopeptidase M significantly reduced blood pressure for up to 40 minutes when infused intracerebroventricularly into anesthetized spontaneously hypertensive rats (SHR) from a mean +/- SEM of 190 +/- 4 to 94 +/- 7 mm Hg and also in normotensive Wistar-Kyoto (WKY) rats from 138 +/- 5 to 68 +/- 8 mm Hg. Cerebrospinal fluid levels of angiotensin II (Ang II) and III were measured by radioimmunoassay and indicated drops with leucine aminopeptidase M infusion in SHR (from 36 +/- 6 to 11 +/- 1 pg/100 microliters) and in WKY rats (from 33 +/- 9 to 13 +/- 1 pg/100 microliters). Pretreatment with the specific angiotensin receptor antagonist [Sar1, Thr8]Ang II (sarthran) significantly diminished the subsequent leucine aminopeptidase M-induced decreases in blood pressure in SHR and facilitated recovery to base level blood pressure and heart rate in blood strains. Thus, exogenous application of leucine aminopeptidase M into the brain lateral ventricles of SHR is temporarily effective at reducing blood pressure, and this effect appears dependent on the brain angiotensinergic system. This treatment also reduced blood pressure in WKY rats; however, pretreatment with sarthran was reasonably ineffective at preventing subsequent leucine aminopeptidase M-induced decreases in blood pressure.

Angiotensin II↗
PubMed1983

Subcellular localisation of leucine aminopeptidase in human polymorphonuclear leukocytes.

Human polymorphonuclear leukocytes were homogenised in isotonic sucrose and subjected to analytical subcellular fractionation by sucrose density gradient centrifugation. The gradient fractions were assayed for leucine aminopeptidase and for principal organelle marker enzymes. Leucine aminopeptidase, when assayed with both L-leucine-7-amido-4-methyl-coumarin and leucyl-2-naphthylamide as substrate, showed a unimodal distribution with an equilibrium density of 1.18 g X cm-3. This distribution was quite distinct from that exhibited by marker enzymes for all the recognized subcellular organelles: there was no leucine aminopeptidase associated with the plasma membrane. Fractionation experiments with neutrophils treated with isotonic sucrose containing a low concentration of digitonin, and studies with the non-permeant ectoenzyme inhibitor, diazotised sulphanilic acid, confirmed that leucine aminopeptidase had a purely intracellular localisation. Fractionation experiments with neutrophils homogenised in sucrose medium containing digitonin, showed leucine aminopeptidase associated with a membrane fraction. It is suggested that leucine aminopeptidase is located to the membrane of a previously unrecognised population of cytoplasmic granules of the human neutrophil.

Cytoplasmic Granules↗