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At least 1,369 records · Page 76Linked to original sources
PubMed2000

Enhancement of human endometrial stromal decidualization by bestatin, an aminopeptidase-N inhibitor.

We have re-evaluated the effects of bestatin, an aminopeptidase-N (CD13) inhibitor, on in vitro decidualization of normal human endometrial stromal cells by using an in vitro decidualization activity assay. Bestatin did not show any effects on the viability of both the decidualizing stromal cells co-stimulated with 8-Br-cAMP and bestatin and the 8-Br-cAMP-induced decidualized stromal cells, or on prolactin release from the decidualized stromal cells. However, bestatin dose-dependently enhanced prolactin release from the decidualizing stromal cells co-stimulated with 8-Br-cAMP and bestatin. These results indicate that bestatin enhances cAMP-mediated decidualization of human endometrial stromal cells and suggests that membrane aminopeptidase-N in the human endometrium is involved in the regulation of endometrial differentiation by inhibiting cAMP-mediated decidualization signals in endometrial stromal cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Role of alanyl aminopeptidase in growth and function of human T cells (review).

Alanyl aminopeptidase (APN, CD13) is highly expressed in human monocytes, and anti-CD13 monoclonal antibodies are well established routine markers in leukaemia typing. Due to activation or malignant transformation other leukocyte subpopulations including human T cells exhibit significant APN-gene and surface expression. The function of leukocyte APN is poorly understood, especially the knowledge of physiological ligands/substrates of the enzyme is limited. Abnormal expression of APN on malignant lymphocytes, the activation-dependent induction of APN expression in peripheral T cells and the strong anti-proliferative effects of aminopeptidase inhibitors lead to the interesting hypothesis of a linkage of APN expression and/or function to leukocyte growth. In support of this hypothesis we detected mutations in the APN-gene of patients suffering from leukaemia or lymphoma. This review outlines evidence for APN contributing to the regulation and realisation of lymphocyte growth and function by modulating the mRNA expression of IL-2, IL-1 receptor antagonist, and TGF-beta1 and increasing the activity of MAP kinase p42/Erk2.

Base Sequence↗
PubMed1992

Prodrugs of peptides. 19. Protection of the pyroglutamyl residue against pyroglutamyl aminopeptidase by N-acyloxymethylation and other means.

The N-terminal pyroglutamyl group in several peptides is specifically cleaved by pyroglutamyl aminopeptidase (PAPase I). With the aim of protecting this group against enzymatic cleavage by the prodrug approach, various derivatives of L-pyroglutamyl benzylamide, used as a PAPase I sensitive model pyroglutamyl peptide, were prepared and their stability characteristics determined. The derivatives studied included phenoxycarbonyl, phthalidyl, hydroxymethyl and actoxymethyl derivatives, all formed at the pyroglutamyl NH-moiety. Whereas L-pyroglutamyl benzylamide was rapidly hydrolyzed by PAPase I, all the derivatives were resistant to cleavage by the enzyme. On the other hand, these derivatives, with the exception of the N-phenoxycarbonyl derivative, were readily converted to the parent pyroglutamyl benzylamide by spontaneous or plasma catalyzed hydrolysis, the half-lives of conversion in 80% human plasma being in the range 2.3-8.4 h. The major degradation reaction of the N-phenoxycarbonyl derivative in both buffer and plasma solutions was hydrolytic opening of the pyrrolidone ring. The pH-rate profiles for the degradation of the compounds in aqueous solution were obtained and both specific acid and base catalytic reactions as well as a spontaneous reaction were observed. The results suggest that N-phthalidylation, N-hydroxymethylation and N-acyloxymethylation of pyroglutamyl peptides may be useful prodrug approaches to protect such peptides against cleavage by pyroglutamyl aminopeptidase and hence to improve their delivery characteristics.

Humans↗
PubMed2003

[Genomic variations in the locus for aminopeptidase N:a putative cellular receptor for SARS-CoV spike glycoprotein].

Aminopeptidase N has been identified as the cellular receptor for human coronavirus HCoV-229E and was a putative receptor for the spike glycoprotein encoded by the SARS-associated coronavirus (SARS-CoV). We report here identification of 9 single nucleotide polymorphisms (SNPs) in ANPEP, encoding human aminopeptidase N, in Chinese. All ANPEP exons and their flanking intronic sequences were amplified from unrelated normal individuals by polymerase chain reaction (PCR) and screened using denaturing high-performance liquid chromatography (DHPLC). Nine SNPs were revealed after direct sequencing of PCR amplified fragments which showed changes of DHPLC chromatogram. Four of these polymorphisms, T321M(962C > T), S651L(1952C > T), S752N(2255G > A) and G764R(2290G > A), were non-synonymous; the remaining exonic synonymous and intronic ones were T795T(2385C > T), IVS7 + 17G > A, IVS14-16A > G, IVS17 + 12C > G and IVS17 + 44C > T. Our data may be useful for studies to investigate the role of host genetic factors in SARS pathogenesis, especially for identifying SARS-susceptible and/or anti-SARS alleles.

Animals↗
PubMed1990

The T cell triggering molecule Tp103 is associated with dipeptidyl aminopeptidase IV activity.

Tp103 is a 103-kDa T cell activation molecule that defines an alternative activation signal for human T lymphocytes. It is absent from or present in only low amounts on resting T cells but is expressed strongly after activation. Cross-linking of Tp103 via a mAb CB.1 leads to triggering of functional activities in preactivated CD3+ T lymphocytes. By using mAb CB.1 in immunohistology we found that Tp103 is expressed in epithelial cells of various tissues, such as kidney, prostate, epidermis and on endothelia of liver, spleen, lungs, and most vessels, and in bile duct canaliculi in the liver. We found a carcinoma cell line expressing Tp103 and could precipitate a 110-kDa molecule from the surface of these cells. We considered several known molecules of similar distribution and molecular mass for identity with Tp103 and show here that Tp103 is probably identical to the proteolytic enzyme dipeptidyl aminopeptidase IV. When we purified Tp103 by affinity chromatography, typical dipeptidyl aminopeptidase IV activity copurified with Tp103. On activated T cells the enzymatic activity associated with Tp103 is expressed on the outside of the cell. We show that mAb CB.1 recognizes the same molecule as the anti-CD26 mAb anti-Ta1. The anti-Ta1 mAb was found to have T cell-activating activity too, but to differ in its requirements for triggering of T lymphocytes.

Antibodies, Monoclonal↗
PubMed1988

Effects of aminopeptidase inhibitors actinonin and amastatin on chemotactic and phagocytic responses of human neutrophils.

Actinonin and amastatin are low-molecular-weight inhibitors of aminopeptidases associated with cell surfaces. The purpose of this study was to determine their effects on human neutrophil functions such as chemotaxis and phagocytosis. Both actinonin and amastatin enhanced chemotaxis to the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine. On the other hand, the effects of both agents on neutrophil phagocytosis were varied. Bacterial attachment to neutrophils was slightly affected by these agents. However, actinonin enhanced the internalization of bacteria by neutrophils. Neutrophil leucine aminopeptidase activity was also determined and was found to be weakly inhibited by these agents.

Anti-Bacterial Agents↗
PubMed1994

Xaa-Pro-dipeptidyl-aminopeptidase from Lactococcus lactis catalyses kinetically controlled synthesis of peptide bonds involving proline.

Xaa-Pro-dipeptidyl-aminopeptidase (EC 3.4.14.5) from Lactococcus lactis (PepX) was used, for the first time, as a catalyst in kinetically controlled synthesis of peptide bonds involving proline. PepX had amidase and esterase activities in addition to peptidase activity. Thus amide and ester derivatives of X-Pro peptides could be employed as acyl donors. PepX showed a broad specificity for the residue in position P'1, accepting a large variety of amino acid amides, esters, peptides as well as free amino acids as nucleophiles. This also indicated that it was not necessary to protect the C-terminus of the nucleophile. The major factors controlling yield, e.g. pH, an excess of nucleophile, ionic strength and type of carboxyl protecting and activating groups, were evaluated. Under optimum reaction conditions (pH 8.5, high excess of nucleophile over acyl donor and moderate ionic strength) the selectivity of the reaction ranged from 5 to 99% depending on the structure of the nucleophile and the acyl donor. Our work contributes to the elucidatation of the mechanism of aminolysis reactions catalysed by an aminopeptidase.

Amino Acid Sequence↗
PubMed1993

BLH1 codes for a yeast thiol aminopeptidase, the equivalent of mammalian bleomycin hydrolase.

We have cloned the BLH1 gene of the yeast Saccharomyces cerevisiae coding for a peptidase with significant homology to rabbit bleomycin hydrolase. Bleomycin is a glycopeptide antibiotic used for the treatment of human cancers. The antitumor activity of the drug is limited by its metabolic inactivation caused by bleomycin hydrolase, a member of the cysteine protease family. The open reading frame of BLH1 consists of 1,449 base pairs encoding a 55.4-kDa protein consistent with the molecular mass found in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The consensus sequence within the active site region of cysteine proteases is conserved in the yeast enzyme. Biochemical studies on the purified enzyme confirm its classification as a thiol protease. The nonvacuolar enzyme has a molecular mass of 220 kDa, suggesting a homotetrameric structure. It exhibits an aminopeptidase activity with broad substrate specificity. Biochemical and genetic linkage data give evidence that the BLH1 and the LAP3 (Trumbly, R. J., and Bradley, G. (1983) J. Bacteriol. 156, 36-48) encoded aminopeptidases are identical. Deletion of the BLH1 gene is not lethal under normal growth conditions. However, blh1 mutants show hypersensitivity to bleomycin, indicating that bleomycin hydrolase is able to inactivate bleomycin in vivo and to protect cells from bleomycin-induced toxicity.

Amino Acid Sequence↗
PubMed1964

THE DIAGNOSTIC VALUE OF SERUM LEUCINE AMINOPEPTIDASE.

Serum leucine aminopeptidase determination was found to be a useful screening procedure for hepatobiliary disease in jaundiced and unjaundiced patients. Values under 1,000 units are of no help in the differential diagnosis of jaundice but values above 1,000 units are highly indicative of biliary obstruction. The differentiation of intra- from extrahepatic obstruction as well as of malignant from benign jaundice cannot generally be established by this single test.

Adolescent↗
PubMed2001

[Leucine aminopeptidase (LAP)].

We regarded the aminopeptidase LAP (EC 3.4.11.1), AA (EC 3.4.11.2), and CAP (EC 3.4.11.3) as a group of enzymes and presented the method of their fractionation. In addition, we described that when an increase in serum "LAP" activity is observed, it is necessary to consider whether it is derived from LAP, AA, or CAP in order to use that data in clinical diagnosis.

Aminopeptidases↗
PubMed1996

Aminopeptidase a is a constituent of activated pericytes in angiogenesis.

Monoclonal antibody (MAb) RC38 recognizes a human renal antigen of 160 kD recently identified as human aminopeptidase A (APA; EC 3.4.11.7). This ectoenzyme is able to hydrolyse selectively N-terminal glutamyl and aspartyl residues from oligopeptides. By enzyme histochemistry, APA activity has also been localized in the microvessels of all organs in animals and man. The purpose of this study was to investigate the distribution of human APA as recognized by MAb RC38 in the microvasculature of normal human tissues and pathological conditions associated with neovascularization. Unexpectedly, in normal tissues vascular staining with MAb RC38 was generally weak and often absent, while in tumours, granulation tissue, and chronic synovitis, marked microvascular staining was demonstrated. By immuno-electron microscopy, the antigen was found on the cell membrane of activated pericytes and their processes in the tumour vasculature. RC38 expression could not be detected on cultured human endothelial cells or pericytes. These observations suggest that pericyte expression of a subtype of APA (as recognized by MAb RC38) is markedly enhanced in the vasculature of tumours and wound healing tissue as compared with normal resting tissues. This provides further evidence of the altered state of pericytes in these conditions. Pericyte APA may be involved in the metabolism of biologically active oligopeptides during neovascularization, supporting a regulatory role of pericytes in this process. In addition, MAb RC38 may be useful as a marker of pericyte activation in tissue sections.

Aminopeptidases↗
PubMed2005

Distribution and cellular localization of insulin-regulated aminopeptidase in the rat central nervous system.

Central infusions of angiotensin IV enhance spatial learning, memory retention and retrieval, neurotransmitter release, and long-term potentiation via interaction with a specific, high-affinity binding site. This site was recently purified and identified as the insulin-regulated aminopeptidase (IRAP). This enzyme was previously characterized as the marker protein of specialized insulin-responsive vesicles containing GLUT4 in muscle and adipose tissue. The present study provides the first comprehensive description of IRAP distribution in the adult rat brain. By using immunohistochemistry, IRAP was found to be highly expressed in selected olfactory regions, in septal and hypothalamic nuclei, throughout the hippocampal formation and cerebral cortex, and in motor and motor associated nuclei. IRAP was expressed exclusively in neurons in these regions. At the cellular level, IRAP was localized within cell bodies, excluding the nucleus, in a punctate vesicular pattern of expression. IRAP-positive immunoreactivity was also found in some proximal processes but was not detected in synaptic nerve terminals. The neurochemical composition of IRAP-containing neurons was further characterized by dual-label immunohistochemistry. IRAP was expressed in cholinergic cell bodies of the medial septum, a source of cholinergic projections to the hippocampus and cerebral cortex. The distribution of IRAP in motor and motor-associated nuclei; the colocalization of the enzyme with potential in vivo substrates, oxytocin and vasopressin in the hypothalamus; and the colocalization with GLUT4 in selected nuclei all suggest diverse physiological roles for IRAP in the rat central nervous system.

Aminopeptidases↗
PubMed2002

Yeast methionine aminopeptidase type 1 is ribosome-associated and requires its N-terminal zinc finger domain for normal function in vivo.

Methionine aminopeptidase type 1 (MetAP1) cotranslationally removes N-terminal methionine from nascent polypeptides, when the second residue in the primary structure is small and uncharged. Eukaryotic MetAP1 has an N-terminal zinc finger domain not found in prokaryotic MetAPs. We hypothesized that the zinc finger domain mediates the association of MetAP1 with the ribosomes and have reported genetic evidence that it is important for the normal function of MetAP1 in vivo. In this study, the intracellular role of the zinc finger domain in yeast MetAP1 function was examined. Wild-type MetAP1 expressed in a yeast map1 null strain removed 100% of N-terminal methionine from a reporter protein, while zinc finger mutants removed only 31-35%. Ribosome profiles of map1 null expressing wild-type MetAP1 or one of three zinc finger mutants were compared. Wild-type MetAP1 was found to be an 80S translational complex-associated protein that primarily associates with the 60S subunit. Deletion of the zinc finger domain did not significantly alter the ribosome profile distribution of MetAP1. In contrast, single point mutations in the first or second zinc finger motif disrupted association of MetAP1 with the 60S subunit and the 80S translational complex. Together, these results indicate that the zinc finger domain is essential for the normal processing function of MetAP1 in vivo and suggest that it may be important for the proper functional alignment of MetAP1 on the ribosomes.

Amino Acid Sequence↗
PubMed1998

Yeast methionine aminopeptidase I can utilize either Zn2+ or Co2+ as a cofactor: a case of mistaken identity?

Yeast methionine aminopeptidase I (MetAP I) is one of two enzymes in Saccharomyces cerevisiae that is responsible for cotranslational cleavage of initiator methionines. It has previously been classified as a Co2+ metalloprotease in all prokaryotic and eukaryotic forms studied. However, treatment of recombinant apo-MetAP I with 12.5 microM Zn2+ produces an enzyme that is as active as that reconstituted with 200 microM Co2+. In the presence of physiological concentrations of reduced glutathione (GSH), Co-MetAP I is inactive, while the activity of Zn-MetAP I is increased more than 1.7-fold over Zn-MetAP I assayed in the absence of GSH. Given that the in vivo concentration of Zn2+ is at least 1,000-fold higher than that of Co2+, and that Co2+ is insoluble in physiological concentrations of GSH, it is probable that yeast MetAP I is actually a Zn2+ metalloprotease. Furthermore, unless there are extraordinary conditions that insulate or sequester them from this reducing milieu, that have yet to be identified, there are not likely to be any cytoplasmic enzymes that use free Co2+.

Aminopeptidases↗
PubMed2007

Serendipitous discovery of novel bacterial methionine aminopeptidase inhibitors.

In this article we describe the application of structural biology methods to the discovery of novel potent inhibitors of methionine aminopeptidases. These enzymes are employed by the cells to cleave the N-terminal methionine from nascent peptides and proteins. As this is one of the critical steps in protein maturation, it is very likely that inhibitors of these enzymes may prove useful as novel antibacterial agents. Involvement of crystallography at the very early stages of the inhibitor design process resulted in serendipitous discovery of a new inhibitor class, the pyrazole-diamines. Atomic-resolution structures of several inhibitors bound to the enzyme illuminate a new mode of inhibitor binding.

Aminopeptidases↗
PubMed2002

The specificity in vivo of two distinct methionine aminopeptidases in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, the essential function of amino-terminal methionine removal is provided cotranslationally by two methionine aminopeptidases (MetAP1 and MetAP2). To examine the individual processing efficiency of each MetAP in vivo, we measured the degree of N-terminal methionine cleavage from a series of mutated glutathione-S-transferase (GST) proteins isolated from yeast wild-type, a map1 deletion strain, a map2 deletion strain, and a map1 deletion strain overexpressing the MAP2 gene. We found that MetAP1 plays the major role in N-terminal methionine removal in yeast. Both MetAPs were less efficient when the second residue was Val, and MetAP2 was less efficient than MetAP1 when the second residue was Gly, Cys, or Thr. These findings indicate that MetAP1 and MetAP2 exhibit different cleavage efficiencies against the same substrates in vivo. Interestingly, although methionine is considered a stabilizing N-terminal residue, we found that retention of the initiator methionine on the Met-Ala-GST mutant protein drastically reduced its half-life in vivo.

Amino Acid Substitution↗
PubMed1996

Evidence that the human homologue of a rat initiation factor-2 associated protein (p67) is a methionine aminopeptidase.

Previously, we cloned a human cDNA encoding a protein which has a 92% amino acid sequence identity to a rat initiation factor-2 associated protein (p67). Rat p67 plays an important role in translational regulation by preventing the phosphorylation of the alpha subunit of initiation factor-2. Interestingly, several lines of indirect evidence suggested that this protein may also function as a methionine aminopeptidase (MetAP). To test this hypothesis, we expressed the human cDNA in a baculovirus system, purified it to homogeneity and characterized it. Using 13 different peptide substrates, we found that the human p67 has a similar substrate specificity with other MetAPs. Kinetic analyses revealed that the Kcat/K(m) values of the human MetAP on two representative substrates are similar to those of yeast and porcine MetAPs. Furthermore, we found that this enzyme, like other MetAPs, is also a cobalt-dependent metalloenzyme.

Aminopeptidases↗
PubMed1997

Trafficking kinetics of the insulin-regulated membrane aminopeptidase in 3T3-L1 adipocytes.

In fat and muscle cells insulin causes the marked translocation of the glucose transporter GLUT4 from its intracellular location to the plasma membrane. We and others have discovered an insulin-regulated membrane aminopeptidase (designated IRAP) that colocalizes with intracellular GLUT4 and also translocates markedly in response to insulin. This study describes the trafficking kinetics of IRAP in 3T3-L1 adipocytes. By means of a surface biotinylation method, the half-time for the increase in IRAP at the plasma membrane in response to insulin was found to be 2 min. The increase was completely blocked by the phosphatidylinositol 3-kinase inhibitor, wortmannin. In insulin-treated cells, biotinylated IRAP, initially at the plasma membrane, equilibrated with the intracellular pool with a half-time of 2 min. Thus, IRAP continuously recycles. Finally, vesicles isolated from the intracellular membranes with antibodies against IRAP and GLUT4 showed the same protein composition. In conjunction with results in the literature, these findings indicate that IRAP and GLUT4 traffic through the same intracellular compartments.

3T3 Cells↗