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PubMed1998

Synthesis and glutathione S-transferase structure-affinity relationships of nonpeptide and peptidase-stable glutathione analogues.

A series of nonpeptidic glutathione analogues where the peptide bonds were replaced by simple carbon-carbon bonds or isosteric E double bonds were prepared. The optimal length for the two alkyl chains on either side of the mercaptomethyl group was evaluated using structure-affinity relationships. Affinities of the analogues 14a-f, 23, and 25 were evaluated for a recombinant GST enzyme using a new affinity chromatography method previously developed in our laboratory. Analysis of these analogues gives an additional understanding for GST affinity requirements: (a) the carbon skeleton must conserve that of glutathione since analogue 14a showed the best affinity (IC50 = 5.2 microM); (b) the GST G site is not able to accommodate a chain length elongation of one methylene group (no affinity for analogues 14c,f); (c) a one-methylene group chain length reduction is tolerated, much more for the "Glu side" (14d, IC50 = 10.1 microM) than for the "Gly side" (14b, IC50 = 1800 microM); (d) the mercaptomethyl group must remain at position 5 as shown from the null affinity of the 6-mercaptomethyl analogue 14e; (e) the additional peptide isosteric E double bond (25) or hydroxyl derivative (23) in 14e did not help to retrieve affinity. This work reveals useful information for the design of new selective nonpeptidic and peptidase-stable glutathione analogues.

Animals↗
PubMed1999

Structure-activity relationship of diaryl phosphonate esters as potent irreversible dipeptidyl peptidase IV inhibitors.

The previously reported diphenyl 1-(S)-prolylpyrrolidine-2(R, S)-phosphonate (5) was used as a lead compound for the development of potent and irreversible inhibitors of dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5). The synthesis of a series of diaryl 1-(S)-prolylpyrrolidine-2(R,S)-phosphonates with different substituents on the aryl rings (hydroxyl, methoxy, acylamino, sulfonylamino, ureyl, methoxycarbonyl, and alkylaminocarbonyl) started from the corresponding phosphites. A good correlation was found between the electronic properties of the substituent and the inhibitory activity and stability. The most striking divergence of this correlation was the high potency combined with a high stability of the 4-acetylamino-substituted derivative 11e. This compound shows low cytotoxicity in human peripheral blood mononuclear cells and also has favorable properties in vivo. Therefore bis(4-acetamidophenyl) 1-(S)-prolylpyrrolidine-2(R,S)-phosphonate (11e) is considered as a major improvement and will be a highly valuable DPP IV inhibitor for further studies on the biological function of the enzyme and the therapeutic value of its inhibition.

Animals↗
PubMed1999

Extensive genetic polymorphism of peptidases A, B, C, and D, in wild rabbit (Oryctolagus cuniculus) populations from the Iberian Peninsula.

Genetic polymorphism of peptidases A, B, C, and D in the wild rabbit (Oryctolagus cuniculus) was assessed by horizontal starch gel electrophoresis, in a total of 1003 individuals comprising 16 Iberian and 2 French populations and 1 domestic stock. Twenty-five different alleles were detected: 6 in PEPA, 4 in PEPB, 8 in PEPC, and 7 in PEPD. The highest values of observed heterozygosity averaged over the four loci were obtained for the southwestern Iberian populations and a clinal loss of variability in a northeastern direction was detected. A clear separation between the two putative subspecies O. c. cuniculus and O. c. algirus was not obtained.

Alleles↗
PubMed2004

A pilot-scale expressed sequence tag analysis of Beauveria bassiana gene expression reveals a tripeptidyl peptidase that is differentially expressed in vivo.

The entomopathogen Beauveria bassiana is a dimorphic fungus that displays an in vivo-specific, yeast-like parasitic phase. In order to study the transcriptome of B. bassiana during this unique developmental phase, we developed a method to harvest in vivo B. bassiana cells from infected Manduca sexta larvae. The infected hemolymph was collected just prior to insect death and subjected to gradient centrifugation, which allowed for separation of the B. bassiana in vivo-produced cells from remaining insect hemocytes. Total RNA was extracted from the harvested fungal cells and used to construct a cDNA library that is representative of B. bassiana gene expression in vivo. Expressed Sequence Tags (ESTs) were generated and led to the cloning of two protease genes. One of these proteases was identified as a tripeptidyl peptidase (Bb TPP). The Bb TPP protease was shown to be up-regulated during infection, and identification of a signal peptide suggested that the enzyme is secreted in the host hemolymph. Although its activity and role have yet to be characterized, the Bb TPP protease appears as a likely candidate for being involved in B. bassiana pathogenesis. The identification of this novel, up-regulated protease also suggests that random sequencing from our in vivo cDNA library may be a valuable step towards identifying biologically active metabolites produced in vivo by B. bassiana.

Aminopeptidases↗
PubMed2003

An essential role for tripeptidyl peptidase in the generation of an MHC class I epitope.

Most of the peptides presented by major histocompatibility complex (MHC) class I molecules require processing by proteasomes. Tripeptidyl peptidase II (TPPII), an aminopeptidase with endoproteolytic activity, may also have a role in antigen processing. Here, we analyzed the processing and presentation of the immunodominant human immunodeficiency virus epitope HIV-Nef(73-82) in human dendritic cells. We found that inhibition of proteasome activity did not impair Nef(73-82) epitope presentation. In contrast, specific inhibition of TPPII led to a reduction of Nef(73-82) epitope presentation. We propose that TPPII can act in combination with or independent of the proteasome system and can generate epitopes that evade generation by the proteasome-system.

Aminopeptidases↗
PubMed2006

Inhibitors of dipeptidyl peptidase IV and aminopeptidase N target major pathogenetic steps in acne initiation.

Acne is a chronic disease hallmarked by sebaceous hyperplasia, follicular hyperkeratosis, and inflammation. Parallel targeting of these factors is required to treat acne effectively. Inhibitors of dipeptidyl peptidase IV (DP IV) and aminopeptidase N (APN) show strong anti-inflammatory effects on immune cells and therapeutic efficacy in autoimmune disorders. Our investigation focused on the expression and functional relevance of these ectopeptidases in three cell types which exhibit an altered phenotype in early acne lesions. We showed for the first time expression of DP IV and APN on human sebocytes. In the SZ95 sebocyte cell line, the DP IV inhibitors Lys[Z(NO2)]-thiazolidide and Lys[Z(NO2)]-pyrrolidide and the APN inhibitors actinonin and bestatin suppressed proliferation, enhanced terminal differentiation, and slightly decreased total neutral lipid production. The anti-inflammatory and differentiation-restoring cytokine IL-1 receptor antagonist was significantly upregulated in SZ95 sebocytes and the HaCaT keratinocyte cell line in the presence of inhibitors. Furthermore, the inhibitors suppressed proliferation and IL-2 production of Propionibacterium acnes-stimulated T cells ex vivo and enhanced the expression of the immunosuppressive cytokine transforming growth factor-beta1. Our data provide first evidence for a functional role of DP IV and APN in the sebaceous gland apparatus and for their inhibitors, used alone or in combination, as completely new substances possibly affecting acne pathogenesis in a therapeutic manner.

Acne Vulgaris↗
PubMed1986

Rat peritoneal mast cells release dipeptidyl peptidase II.

Purified rat peritoneal mast cells have a 10-20-fold higher dipeptidyl peptidase II (DPP II) activity as compared with that of macrophages from the same source. Upon stimulation with the secretagogue Compound 48/80, DPP II is released from peritoneal-lavage cells and from purified mast cells, but not from purified macrophages, in a dose-dependent manner. Maximally, about one-third of the DPP II present in peritoneal-lavage cells is released. Substance P and the antigen/IgE system probably produce a similar effect. Both histamine and Zn2+, two ingredients of mast-cell granules, strongly inhibit DPP II at concentrations reported to occur in the granules. A possible role of mast-cell DPP II in the remodelling of connective tissue is discussed.

Animals↗
PubMed1990

Immunological cross-reactivity between human tripeptidyl peptidase II and fibronectin.

Tripeptidyl peptidase II (TPP II) is a large intracellular exopeptidase with an active site of the subtilisin type. Affinity-purified hen antibodies against human erythrocyte TPP II cross-reacted with fibronectin in an immunoblot analysis. Furthermore, antibodies against human fibronectin cross-reacted with TPP II. Antibodies against a 65 kDa cell-binding fragment of fibronectin specifically reacted with TPP II, whereas antibodies against the collagen-binding domain, the main heparin-binding domain or the N-terminal fibrin-binding domain did not react. Moreover, the affinity-purified antibodies against TPP II reacted with a 105 kDa cell-binding fragment of fibronectin but not with the fibrin-binding domain or the collagen-binding domain. When native TPP II was dissociated into smaller units through dialysis against a dilute Tris buffer, it could be digested by chymotrypsin into three stable fragments of 70 kDa, 42 kDa and 20 kDa. It could be demonstrated that the 42 kDa fragment was specifically recognized by antibodies against the 65 kDa cell-binding fragment of fibronectin. Furthermore, labelling with di-[3H]isopropyl phosphorofluoridate and N-terminal sequence determination showed that the 70 kDa fragment contained the active-site serine residue. In conclusion, our findings suggest that one domain of the TPP II molecule bears structural resemblance to a cell-binding fragment of fibronectin.

Amino Acid Sequence↗
PubMed1998

Dipeptidyl peptidase III is a zinc metallo-exopeptidase. Molecular cloning and expression.

We have purified dipeptidyl peptidase III (EC 3.4.14.4) from human placenta. It had a pH optimum of 8.8 and readily hydrolysed Arg-Arg-beta-naphthylamide. Monoamino acid-, Gly-Phe-, Gly-Pro- and Bz-Arg-beta-naphthylamides were not hydrolysed at all. The enzyme was inhibited by p-chloromercuriphenylsulphonic acid, metal chelators and 3,4-dichloroisocoumarin and contained 1 mol of zinc per mol of enzyme. The zinc dissociation constant was 250 fM at pH 7. 4 as determined by the zinc binding study. We isolated, by immunological screening of a Uni-ZAP XR cDNA library constructed from rat liver mRNA species, a cDNA clone with 2633 bp encoding the rat enzyme. The longest open reading frame encodes a 827-residue protein with a theoretical molecular mass of 92790 Da. Escherichia coli SOLR cells were infected with the pBluescript phagemid containing the cloned cDNA and established the overexpression of a protein that hydrolysed Arg-Arg-beta-naphthylamide. The recombinant protein was purified and the amino acid sequence of the protein was confirmed. We presumed that the putative zinc-binding domain involved in catalysis was present in the recombinant enzyme. It was a novel zinc-binding motif in that one amino acid residue was inserted into the conserved HEXXH motif characteristic of the metalloproteinases.

Amino Acid Sequence↗
PubMed2002

The insert within the catalytic domain of tripeptidyl-peptidase II is important for the formation of the active complex.

Tripeptidyl-peptidase II (TPP II) is a large (Mr>10(6)) tripeptide-releasing enzyme with an active site of the subtilisin-type. Compared with other subtilases, TPP II has a 200 amino-acid insertion between the catalytic Asp44 and His264 residues, and is active as an oligomeric complex. This study demonstrates that the insert is important for the formation of the active high-molecular mass complex. A recombinant human TPP II and a murine TPP II were found to display different complex-forming characteristics when over-expressed in human 293-cells; the human enzyme was mainly in a nonassociated, inactive state whereas the murine enzyme formed active oligomers. This was surprising because native human TPP II is purified from erythrocytes as an active oligomeric complex, and the amino-acid sequences of the human and murine enzymes were 96% identical. Using a combination of chimeras and a single point mutant, the amino acid responsible for this difference was identified as Arg252 in the recombinant human sequence, which corresponds to a glycine in the murine sequence. As Gly252 is conserved in all sequenced variants of TPP II, the recombinant enzyme with Arg252 is atypical. Nevertheless, as Arg252 evidently interferes with complex formation, and this residue is close to the catalytic His264, it may also explain why oligomerization influences enzyme activity. The exact mechanism for how the G252R substitution interferes with complex formation remains to be determined, but will be of importance for the understanding of the unique properties of TPP II.

Amino Acid Sequence↗
PubMed1998

The conversion of recombinant human mast cell prochymase to enzymatically active chymase by dipeptidyl peptidase I is inhibited by heparin and histamine.

Chymase, a major product of mast cell activation, is secreted as a fully active enzyme. We have prepared recombinant human prochymase and have investigated the conditions under which it may be activated by dipeptidyl peptidase I (DPP I). The gene for human chymase was cloned in a baculovirus vector and expressed in High Five insect cells, and the recombinant protein purified by heparin-agarose and gel-filtration chromatography. The purified prochymase was homogeneous by SDS/PAGE with the same molecular mass as native human chymase, and its identity confirmed by N-terminal sequence analysis and Western blotting with chymase-specific antibodies. Treatment with DPP I to remove the N-terminal dipeptide prosequence resulted in enzymatically active chymase, with substrate and inhibitor profiles very similar to those of the native human enzyme. The activation of prochymase by DPP I was strongly inhibited by heparin (IC50 = 0.5 microg ml[-1]) and histamine (IC50 = 2 mM), though these mast cell products had little effect on the action of DPP I towards a low molecular-mass substrate. The pH optimum of DPP I was also higher and narrower with prochymase. The inhibitory action of heparin was lost at NaCl or KCl concentrations sufficient to elute prochymase from a heparin agarose column. Dextran sulphate was as inhibitory as heparin, whereas chondroitin sulphate C was more than 10-fold less effective. Our findings suggest that the activation of prochymase might be restricted to the early stages of vesicle maturation, when the pH is close to neutrality and the histamine and heparin concentrations are low.

Amino Acid Sequence↗
PubMed1989

Changes of dipeptidyl peptidase (DP IV) activity in the T lymphocytes of rats following administration of ACTH, dexamethasone and opiates.

The aim of the work was to study the effect of glucocorticoids, opiates and stressful stimuli on dipeptidyl peptidase IV (DP IV, EC 3.4.14.5) activity of T lymphocytes prepared from the thymus of intact and adrenalectomized rats. Four week old male rats of Wistar strain were used. The in vivo administration of ACTH, dexamethasone and morphine treatment resulted in an increase of DP IV activity in the cell suspension. In adrenalectomized rats ACTH treatment failed to modify the enzyme activity, however, pain or emotional stress resulted in an elevated DP IV activity. Morphine and D-Met2-Pro5-enkephalinamide resulted in a dose dependent activation of DP IV in T cells, an effect which could be modified by naloxone pretreatment. Our findings show that DP IV mechanisms in T cells are highly sensitive to exogenous and endogenous steroids, opiates and biologically active substances released in response to stress in rats.

Adrenocorticotropic Hormone↗
PubMed1990

Mechanism of L-leucyl-L-leucine methyl ester-mediated killing of cytotoxic lymphocytes: dependence on a lysosomal thiol protease, dipeptidyl peptidase I, that is enriched in these cells.

Exposure of murine or human lymphocytes to L-leucyl-L-leucine methyl ester (Leu-Leu-OMe) results in selective killing of cytotoxic lymphocytes, whereas helper T cells and B cells remain functionally intact. Cytolytic lymphocytes incubated in the presence of toxic concentrations of Leu-Leu-OMe were found to contain membranolytic metabolites of the structure (Leu-Leu)n-OMe, where n greater than or equal to 3. The sensitivity of cytotoxic lymphocytes to Leu-Leu-OMe was found to be dependent upon production of these metabolites by a lysosomal thiol protease, dipeptidyl peptidase I, which is present at far higher levels in cytotoxic lymphocytes than in cells without cytolytic potential or not of bone marrow origin. Thus, this granule enzyme is required for the unique effects of Leu-Leu-OMe and may provide a target for the development of other immunotherapeutic agents designed to delete cytotoxic lymphocyte responses.

Ammonium Chloride↗
PubMed1999

Dipeptidyl peptidase I is required for the processing and activation of granzymes A and B in vivo.

Dipeptidyl peptidase I (DPPI) is a lysosomal cysteine protease that has been implicated in the processing of granzymes, which are neutral serine proteases exclusively expressed in the granules of activated cytotoxic lymphocytes. In this report, we show that cytotoxic lymphocytes derived from DPPI-/- mice contain normal amounts of granzymes A and B, but these molecules retain their prodipeptide domains and are inactive. Cytotoxic assays with DPPI-/- effector cells reveal severe defects in the induction of target cell apoptosis (as measured by [(125)I]UdR release) at both early and late time points; this defect is comparable to that detected in perforin-/- or granzyme A-/- x B-/- cytotoxic lymphocytes. DPPI therefore plays an essential role in the in vivo processing and activation of granzymes A and B, which are required for cytotoxic lymphocyte granule-mediated apoptosis.

Animals↗
PubMed1997

Molecular cloning, chromosomal localization, and expression of murine dipeptidyl peptidase I.

Dipeptidyl peptidase I (DPPI) is a lysosomal cysteine protease that catalyzes the sequential removal of dipeptides from the amino termini of various protein substrates. We have isolated a cDNA coding for murine DPPI from mouse thymus and spleen cDNA libraries. The deduced amino acid sequence codes for a protein of 462 amino acid residues; comparison of this deduced sequence with that of rat and human DPPI revealed 90.1% and 77.8% identity, respectively. Using DPPI cDNA, we obtained two BAC (Bacterial Artificial Chromosome) clones that contained the murine DPPI locus. The DPPI gene consists of seven exons and 6 introns, and spans approximately 20 kilobases. Using fluorescence in situ chromosome hybridization, we localized murine DPPI to chromosome 7D3-E1.1. We determined that DPPI protein is widely distributed in mouse tissues, although its relative abundance varies from tissue to tissue. In contrast to previous reports, we show here that DPPI mRNA and protein levels and enzymatic activity are unchanged during in vitro T cell activation, implying that this enzyme is not rate-limiting for granzyme processing.

Amino Acid Sequence↗
PubMed1998

Regulated expression, processing, and secretion of dog mast cell dipeptidyl peptidase I.

Dipeptidyl peptidase I (DPPI) is a cysteine protease found predominantly in myelomonocytic cells, cytotoxic T-cells, and mast cells. Recent studies identify an intracellular role for mast cell-DPPI (MC-DPPI) by activating prochymase and protryptase to their mature forms. To better define MC-DPPI and to explore the possibility of extracellular roles, we purified MC-DPPI from mastocytoma cells. We found the dog C2 mastocytoma cell line to be the richest source yet described for DPPI, purifying up to 200 microg of enzyme per g of cells. Dog MC-DPPI has an Mr of approximately 175,000 and consists of four subunits, each composed of a propeptide, light chain, and heavy chain. The heavy chain is N-glycosylated and is heterogeneously processed to three different forms. NH2-terminal sequences of the heavy chain and propeptide are identical to those predicted from a cDNA clone we sequenced from a mastocytoma cDNA library. The dog cDNA-derived sequence is 86% identical to that of human DPPI. Dog mastocytoma cells incubated with 12-O-tetradecanoylphorbol-13-acetate increase expression of MC-DPPI mRNA. MC-DPPI maintains its activity for dipeptide substrates at a neutral to alkaline pH. Cells stimulated with ionophore or substance P secrete MC-DPPI in parallel with the granule-associated mediators tryptase and histamine. Thus, dog mastocytoma cells secrete DPPI that is active at the pH of extracellular fluids, suggesting that MC-DPPI may act outside the cell.

Amino Acid Sequence↗
PubMed2006

Need for tripeptidyl-peptidase II in major histocompatibility complex class I viral antigen processing when proteasomes are detrimental.

CD8(+) T lymphocytes recognize infected cells that display virus-derived antigenic peptides complexed with major histocompatibility complex class I molecules. Peptides are mainly byproducts of cellular protein turnover by cytosolic proteasomes. Cytosolic tripeptidyl-peptidase II (TPPII) also participates in protein degradation. Several peptidic epitopes unexpectedly do not require proteasomes, but it is unclear which proteases generate them. We studied antigen processing of influenza virus nucleoprotein epitope NP(147-155), an archetype epitope that is even destroyed by a proteasome-mediated mechanism. TPPII, with the assistance of endoplasmic reticulum trimming metallo-aminopeptidases, probably ERAAP (endoplasmic reticulum aminopeptidase associated with antigen processing), was crucial for nucleoprotein epitope generation both in the presence of functional proteasomes and when blocked by lactacystin, as shown with specific chemical inhibitors and gene silencing. Different protein contexts and subcellular targeting all allowed epitope processing by TPPII as well as trimming. The results show the plasticity of the cell's assortment of proteases for providing ligands for recognition by antiviral CD8(+) T cells. Our observations identify for the first time a set of proteases competent for antigen processing of an epitope that is susceptible to destruction by proteasomes.

Acetylcysteine↗
PubMed1999

Purification and characterization of a novel dipeptidyl peptidase from Dictyostelium discoideum.

A dipeptidyl peptidase (DPP) was purified to homogeneity using lys-ala-beta-naphthylamide, the standard substrate for DPP II. The enzyme is a monomer with a Mr of 70kDa, pl 5.2, and Km 5.0 microM. Its terminal amino acid sequence was XXLLYAIQKRLF and was not identical to that of any known protein. Although initially considered to be a DPP II, the enzyme differed in some properties from classical DPP IIs. It had a pH optimum of 7.9, was not active on X-pro-naphthylamides, the usual substrates of mammalian DPP II, but was active on arg-arg- and asp-arg-naphthylamides, substrates acted on by the DPP III class of enzymes. This enzyme therefore combines properties typical of both DPP II and III and differs from all previously described DPPs. Activity on lys-ala-beta-naphthylamide was most abundant during aggregation and its activity is consistent with processing specific peptides during development.

Aminopeptidases↗