SEARCH · Search PubMed

Results for “PEPTIDASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

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

At least 451 records · Page 25Linked to original sources

PubMed1990

Peptidase activity as a determinant of agonist potencies in some smooth muscle preparations.

The influence of degradation by peptidases on concentration-response relationships for peptide agonists of the tachykinin and bombesin-like families was investigated. The combined presence of three peptidase inhibitors, phosphoramidon (1 microM), captopril (1 microM) and bestatin (100 microM), had no significant effect on the onset rates or peak contractile responses to these peptides in the rat urinary bladder and guinea-pig taenia caeci preparations, or on their peak potentiation of the contractile response to field-stimulation in the guinea-pig vas deferens preparation. However, rates of offset of the response to tachykinins were markedly prolonged in tissues treated with peptidase inhibitors. In experiments designed to estimate clearance of applied peptide from the organ bath, there was an initial rate of loss with the guinea-pig vas deferens and taenia caeci which, measured over the first 5 min, had a half-time of 2-3 min which was then prolonged to 6-8 min in the presence of peptidase inhibitors. These results show that although peptide breakdown can be demonstrated in these systems, it seems not to be an important determinant of relative pharmacological activity measured in terms of peak response.

Animals↗

PubMed1988

Mitochondrial protein import: identification of processing peptidase and of PEP, a processing enhancing protein.

Transport of nuclear-encoded precursor proteins into mitochondria includes proteolytic cleavage of amino-terminal targeting sequences in the mitochondrial matrix. We have isolated the processing activity from Neurospora crassa. The final preparation (enriched ca. 10,000-fold over cell extracts) consists of two proteins, the matrix processing peptidase (MPP, 57 kd) and a processing enhancing protein (PEP, 52 kd). The two components were isolated as monomers. PEP is about 15-fold more abundant in mitochondria than MPP. It is partly associated with the inner membrane, while MPP is soluble in the matrix. MPP alone has a low processing activity whereas PEP alone has no apparent activity. Upon recombining both, full processing activity is restored. Our data indicate that MPP contains the catalytic site and that PEP has an enhancing function. The mitochondrial processing enzyme appears to represent a new type of "signal peptidase," different from the bacterial leader peptidase and the signal peptidase of the endoplasmic reticulum.

Amino Acid Sequence↗

PubMed1989

Detection of parasite peptidase in the plasma of heifers infected with Trypanosoma congolense.

Plasma samples from heifers infected with Trypanosoma congolense were shown to contain a parasite peptidase. In some instances, trypanosome peptidase was detected in plasma samples taken from heifers for up to 14 days after infections had been successfully treated with diminazene aceturate (Berenil). Trypanosome peptidase was detected in plasma using starch gel electrophoresis and also by a dot blot assay in which a McAb, raised against the enzyme, was spotted onto nitrocellulose filters which were then used to absorb enzyme from the samples. The molecular weight of the enzyme was approximately 60,000. The possible role that a trypanosome peptidase may play in inducing pathology and its use in the diagnosis of infection and disease are discussed.

Animals↗

PubMed1996

Substrates containing phosphorylated residues adjacent to proline decrease the cleavage by proline-specific peptidases.

Thirteen dipeptide rho-nitroanilides of the common structure H-Xaa-Pro-4-NA (Xaa = serine, threonine and tyrosine) and seven tripeptide rho-nitroanilides of the common structure H-Gly-Xaa-Pro-4-NA (Xaa = serine or threonine) were prepared and analyzed as substrates of the proline-specific peptidases dipeptidyl peptidase IV and prolyl endopeptidase, respectively. The side chains of the hydroxy amino acids were synthetically modified by various acyl-, benzyl- and phosphate residues. The presence of aliphatic or aromatic residues attached to the side chain of the P2-hydroxy amino acids resulted in no significant change of the specificity constants of the enzyme-catalyzed substrate hydrolysis. In some cases, however, substrate inhibition was observed. In contrast, the reactivity of dipeptidyl peptidase IV and prolyl endopeptidase decreases more than two orders of magnitude towards the phosphorylated di- and tripeptide substrates compared to the hydrolysis of unmodified substrates. The kinetic data obtained with the model compounds suggest that side-chain modification of proline-containing peptide substrates may influence their resistance towards the hydrolytic activity of proline-specific hydrolases. Additionally, the results support that structural changes of the substrate during enzyme-hydrolysis may be involved in the mechanism of action of proline-specific serine peptidases. From this result we speculate that posttranslational phosphorylation of peptide sequences found in protein kinase recognition motifs such as -Xaa-Ser/Thr-Pro-Yaa- and -Xaa-Pro-Ser/Thr-Yaa- may serve as structural determinants that modulate their proteolytic stability.

Amino Acid Sequence↗

PubMed1994

Glutamine-based dipeptides are utilized in mammalian cell culture by extracellular hydrolysis catalyzed by a specific peptidase.

A murine hybridoma (CC9C10) was grown in media containing alanyl-glutamine (ala-gln) or glycyl-glutamine (gly-gln) as a substitute for glutamine. High cell yields were obtained in the presence of 6 mM ala-gln or 20 mM gly-gln. The final cell yield in gly-gln was 14% higher than in gln. Monoclonal antibody productivity was comparable in gln, ala-gln or gly-gln. Substrate utilisation and metabolism was affected by the presence of the dipeptides, particularly with gly-gln. The specific consumption rates of glucose and six amino acids were reduced. Also the accumulation of ammonia and lactate was significantly lower. The higher concentration of gly-gln was necessary for cell growth because of the presence of a peptidase with a lower affinity for gly-gln. The peptidase activity of the basal medium and serum was low. However, a substantial peptidase activity was found in the cytosolic fraction of the cells with an apparent Km of 1.2 mM with respect to ala-gln and 14 mM with respect to gly-gln. It is proposed that the mechanism of dipeptide utilisation involves extracellular hydrolysis by this peptidase following its release into the culture medium.

Amino Acids↗

PubMed2004

Identification of a glutamine residue essential for catalytic activity of aspergilloglutamic peptidase by site-directed mutagenesis.

Aspergilloglutamic peptidase (AGP, formerly called aspergillopepsin II) from Aspergillus niger var. macrosporus is a unique acid protease recently classified to the peptidase family G1. Our previous study using site-directed mutagenesis on the glutamic and aspartic acid residues of AGP conserved among the G1 family suggested that Glu219 and Asp123 (numbering in the preproform) are important for catalytic activity. However, the Asn mutant of Asp123 retained weak but significant activity and therefore it was unclear whether it is an active site residue. In this study, we performed site-directed mutagenesis on all the other hydrophilic residues including Gln, Asn, Ser, Thr, and Tyr, conserved in this family to screen other residues that might be essential for catalytic function, and found that mutations of only Gln133 resulted in almost complete loss of enzymatic activity without change in the native conformation of the enzyme. Meanwhile, the 3D structure of scytalidoglutamic peptidase, a homologue from Scytalidium lignicolum, has been reported, indicating that Glu136 and Gln53 (the counterparts of Glu219 and Gln133 in AGP) form a catalytic dyad. Therefore, the results obtained in this and our previous studies provide with complementary evidence for the definitive conclusion on the catalytic function of the Glu/Gln dyad in glutamic peptidases.

Amino Acid Sequence↗

PubMed2004

Molecular characterisation of five trypsin-like peptidase transcripts from the salmon louse (Lepeophtheirus salmonis) intestine.

Four novel trypsin-like S1A peptidase transcripts (LsTryp2-5) from the marine parasitic copepod Lepeophtheirus salmonis were characterised based on analyses of 1918 expressed sequence tags from two adult female libraries. In addition, one previously described salmon louse trypsin, LsTryp1, has been further characterised. The five peptidases possessed all residues typically found in trypsins in correct sequence contexts. Interestingly, two cysteine residues, possibly involved in a disulphide bridge not previously reported in trypsins are conserved in all louse trypsin sequences. Phylogenetic analyses showed that the five louse peptidases form a monophyletic group with other crustacean trypsins (Brachyurin Ts). Quantitative PCR analyses demonstrated increased transcript levels from planktonic to early host-attached stages and from preadult to sexually mature adult stages. Furthermore, sex-specific differences in transcription regulation were found. In situ hybridisation demonstrated that all five trypsin-like peptidases are transcribed throughout the undifferentiated midgut, indicating a digestive function. The sequence characteristics, histological localisation and transcript regulation suggest that LsTryp1-4 encode typical digestive trypsins. LsTryp5, however, showed some sequence and regulatory peculiarities that rendered its function less clear. Our findings support earlier suggestions for the function of the midgut cells and suggest the existence of an additional undifferentiated cell-type.

Amino Acid Sequence↗

PubMed2006

Peptidases and gp63-like proteins in Herpetomonas megaseliae: possible involvement in the adhesion to the invertebrate host.

The cell-associated and extracellular peptidases of Herpetomonas megaseliae grown in brain-heart infusion and in modified Roitman's complex media were analyzed by measuring peptidase activity on gelatin, casein and hemoglobin in zymograms. Casein was the best proteinaceous substrate for the peptidase detection on both growth conditions. However, no proteolytic activity was detected when hemoglobin was used. Our results showed that cellular cysteine peptidase (115-100, 40 and 35 kDa) and metallopeptidase (70 and 60 kDa) activities were detected on both media in casein and gelatin zymograms. Additionally, the use of casein in the gel revealed a distinct acidic metallopeptidase of 50 kDa when the parasite was cultured in the modified Roitman's complex medium. Irrespective of the culture medium composition, H. megaseliae released metallopeptidases exclusively in the extracellular environment. The presence of gp63-like molecules on the H. megaseliae surface was shown by flow cytometry using anti-gp63 antibody raised against recombinant gp63 from Leishmania mexicana. The pre-treatment of parasites with phospholipase C reduced the number of gp63-positive cells, suggesting that these molecules were glycosylphosphatidylinositol-anchored to the surface. Additionally, the supernatant obtained from phospholipase C-treated cells and probed with anti-cross-reacting determinant confirmed that at least a 52 kDa gp63-like molecule is glycosylphosphatidylinositol-anchored. Furthermore, we assessed a possible function for the gp63-like molecules in H. megaseliae on the interaction with explanted guts of its original host, Megaselia scalaris, and with an experimental model employing Aedes aegypti. Parasites pre-treated with either anti-gp63 antibody or phospholipase C showed a significant reduction in the adhesion to M. scalaris and A. aegypti guts. Similarly, the pre-treatment of the explanted guts with purified gp63 diminished the interaction process. Collectively, these results corroborate the ubiquitous existence of gp63 homologues in insect trypanosomatids and the potential adhesion of these molecules to invertebrate host tissues.

Aedes↗

PubMed2006

Effects of NAAG peptidase inhibitor 2-PMPA in model chronic pain - relation to brain concentration.

N-acetylated-alpha-linked-acidic peptidase (NAAG peptidase) converts N-acetyl-aspartyl-glutamate (NAAG, mGluR3 agonist) into N-acetyl-aspartate and glutamate. The NAAG peptidase inhibitor 2-PMPA (2-(phosphonomethyl)pentanedioic acid) had neuroprotective activity in an animal model of stroke and anti-allodynic activity in CCI model despite its uncertain ability to penetrate the blood-brain barrier. The NAAG concentration in brain ECF under basal conditions and its alteration in relation to the brain ECF concentration of 2-PMPA is unclear. We therefore assessed those brain concentrations after i.p. administration of 2-PMPA, using in vivo microdialysis combined with LC/MS/MS analysis. Administration of 2-PMPA (50mg/kg) produced a mean peak concentration of 2-PMPA of 29.66+/-8.1microM. This concentration is about 100,000 fold more than is needed for inhibition of NAAG peptidase, and indicates very good penetration to the brain. Application of 2-PMPA was followed by a linear increase of NAAG-concentration reaching a maximum of 2.89+/-0.42microM at the end of microdialysis. However, during the time the anti-allodynic effects of 2-PMPA were observed, the NAAG concentration in the ECF did not reach levels which are likely to have an impact on any known target. It appears therefore that the observed behavioural effects of 2-PMPA may not be mediated by NAAG nor, in turn, by mGluR3 receptors.

Analgesics, Non-Narcotic↗

PubMed1990

Leukotriene A4 hydrolase: an epoxide hydrolase with peptidase activity.

Purified leukotriene A4 hydrolase from human leukocytes is shown to exhibit peptidase activity towards the synthetic substrates alanine-4-nitroanilide and leucine-4-nitroanilide. The enzymatic activity is abolished after heat treatment (70 degrees C, 30 min). At 37 degrees C these substrates are hydrolyzed at a rate of 380 and 130 nmol/mg/min, respectively, and there is no enzyme inhibition during catalysis. Apo-leukotriene A4 hydrolase, obtained by removal of the intrinsic zinc atom, exhibits only a low peptidase activity which can be restored by the addition of stoichiometric amounts of zinc. Reconstitution of the apoenzyme with cobalt results in a peptidase activity which exceeds that of enzyme reactivated with zinc. Preincubation of the native enzyme with leukotriene A4 reduces the peptidase activity. Semipurified preparations of bovine intestinal aminopeptidase and porcine kidney aminopeptidase do not hydrolyze leukotriene A4 into leukotriene B4.

Aminopeptidases↗

PubMed1997

Peptidases of the peripheral chemoreceptors: biochemical, immunological, in vitro hydrolytic studies and electron microscopic analysis of neutral endopeptidase-like activity of the carotid body.

The purposes of the present study are to identify and characterize the major peptidase(s) that may be involved in the inactivation of neuropeptides in the mammalian carotid body. Measurements of a number of peptidase activities in the cell-free extract of the cat carotid body using specific substrates and inhibitors indicated that the previously identified neutral endopeptidase (NEP)-like activity [Kumar et al., Brain Res., 517 (1990) 341-343] is the major peptidase in the chemoreceptor tissue. The NEP-like activity of the carotid body was further characterized using a monoclonal antibody to human neutral endopeptidase, EC 3.4.24.11. Immune blot analysis indicated strong immunoreactivity toward the cat and calf carotid bodies but a weak cross-reactivity with the rabbit carotid body. Furthermore, western blot analysis of the cat carotid body extract revealed the presence of a major 97-kDa protein and a minor 200-kDa protein. The 97-kDa NEP form of the carotid body was comparable to EC 3.4.24.11 and was consistent with its reported molecular weight suggesting NEP-like activity of the carotid body is structurally similar to the neutral endopeptidase, EC 3.4.24.11. In order to assess whether NEP is the primary peptide degrading activity in the cat carotid body in vitro hydrolysis studies using substance P (SP) as a model peptide were performed. HPLC analysis showed that SP is hydrolyzed maximally at pH 7.0 by carotid body peptidases with the formation of SP(1-7) and SP(1-8) as stable intermediates. Inhibitors specific to NEP also inhibited the SP-hydrolyzing activity of the carotid body. Analyses of the cell-free extracts showed the occurrence of both NEP and SP-hydrolyzing activities in the rabbit and rat carotid bodies although at 2- and 4-fold lower levels respectively than that observed in the cat carotid body. Immunoelectron microscopy showed that NEP-specific immunoreactivity is associated with the intercellular region between the type I cells and cell clusters of the carotid body. Taken together, the results from this investigation demonstrate that neutral endopeptidase (EC 3.4.24.11) is one of the major endopeptidases which mediates the degradation and inactivation of neuropeptides in the carotid body.

Animals↗

PubMed1975

The presence of peptidases in the rabbit hypothalamus capable of inactivating luteinizing hormone-releasing hormone.

The presence of peptidases in the rabbit hypothalamus capable of inactivating luteinizing hormone-releasing hormone (LH-RH) was investigated with the use of a sensitive and specific radioimmunoassay for the releasing hormone. Enzymes acting on LH-RH were found in two fractions from rabbit hypothalami, a particulate fraction and a supernatant fraction, which very rapidly inactivated the decapeptide. Peptidase activity in the particulate fraction from male and female rabbits was approximately the same, but the supernatant fraction from female animals had significantly greater peptidase activity than that from male animals. These findings confirm the hypothesis that rabbit hypothalamus contains peptidases which inactivate LH-RH, and give some indication that the enzymes may be involved in the control by the central nervous system of reproductive function.

Animals↗

PubMed2000

Heat-shock protein 90: intrinsic peptidase activity and in vitro long-term self-processing.

When tested on Suc-Leu-Leu-Val-Tyr-MCA as substrate, purified full-length hsp90 displays a low "chymotrypsin-like" peptidase activity which is activated by Ca++ and Mg++ ions. On the other hand, using long-term in vitro experiments, we demonstrate the ability of hsp90 to convert into a 73 kDa truncated product. This autocatalytic degradation proceeds from the C-terminal end of the full-length hsp90 and shifts the oligomers toward monomeric truncated forms. This corresponds to an intermolecular process as addition of exogenous 73 kDa product speeds up the maturation kinetics. The peptidase activity is enhanced in the 73 kDa product and is sensitive to peptide aldehyde inhibitors but only partially to lactone compounds. The degradation process itself presents a great degree of similarity with the peptidase activity toward either the inhibitors or the tested ions. Neither 20S proteasome nor m-calpain are responsible for the observed activities. Indeed, the self-processing is a consequence of the peptidase activity which appears to be an intrinsic property of the chaperone. The functional importance of these findings is discussed.

Animals↗

PubMed2001

Kinetic constants of signal peptidase I using cytochrome b5 as a precursor substrate.

A procedure is described for measuring Escherichia coli signal peptidase I activity which exploits an intact precursor protein composed of the alkaline phosphatase signal peptide fused to the full length mammalian cytochrome b5. This cytochrome b5 precursor protein has been extensively characterised and shown to be processed accurately by purified signal peptidase I [Protein Expr. Purif. 7 (1996) 237]. The amphipathic, chimaeric cytochrome b5 precursor was isolated in mg quantities in a highly homogeneous state under non-denaturing conditions. The processing of the cytochrome b5 precursor by signal peptidase displayed Michaelis-Menten kinetics with K(m)=50 microM and k(cat)=11 s(-1). The K(m) was 20-fold lower than that obtained with signal peptide substrates and 3-fold higher than that reported for pro-OmpA-nuclease A precursor fusion. The corresponding turnover number, k(cat), was four orders of magnitude greater than the peptide substrates but was 2-fold lower than pro-OmpA-nuclease A precursor fusion. These results confirm that both the affinities and the catalytic power of the signal peptidase are significantly higher for macromolecular precursor substrates than for the shorter signal peptide substrates.

Alkaline Phosphatase↗

PubMed2001

PCR primers and functional probes for amplification and detection of bacterial genes for extracellular peptidases in single strains and in soil.

A set of primers and functional probes was developed for the detection of peptidase gene fragments of proteolytic bacteria. Based on DNA sequence data, degenerate PCR primers and internal DIG-labeled probes specific for genes encoding alkaline metallopeptidases (apr) (E.3.4.24), neutral metallopeptidases (npr) (E.3.4.24) and serine peptidases (sub) (E.3.4.21) were derived by multiple sequence alignments. Type strains with known peptidase genes and proteolytic bacteria from a grassland rhizosphere soil, a garden soil and an arable field were investigated for their genotypic proteolytic potential. For 52 out of 53 proteolytic bacterial isolates, at least one of the three peptidase classes could be identified by this approach. The amplified gene fragments were of the expected sizes with each of the three primer sets. The functional probes APR, NPR and SUB have been shown to hybridize specifically to the corresponding gene fragments. sub and npr genes were mainly found in Bacillus species. apr genes were only found in the Pseudomonas fluorescens biotypes and in two morphologically identical Flavobacterium-Cytophaga strains from two different sites. In most of the Bacillus spp., both sub and the npr and in the Flavobacterium-Cytophaga strains even all the three genes could be detected. PCR with DNA isolated from soil led to one main product of the expected size with each primer pair whose identity was additionally confirmed by Southern blot hybridization with the corresponding probes.

Bacteria↗

PubMed2002

Enhanced in vivo activity of peptidase-resistant analogs of the insect kinin neuropeptide family.

The diuretic/myotropic insect kinin neuropeptides, which share the common C-terminal pentapeptide core FX(1)X(2)WG-NH(2), reveal primary (X(2)-W) and secondary (N-terminal to F) sites of susceptibility to peptidases bound to corn earworm (H. zea) Malpighian tubule tissue. Analogs designed to enhance resistance to tissue-bound peptidases, and pure insect neprilysin and ACE, demonstrate markedly enhanced in vivo activity in a weight gain inhibition assay in H. zea, and strong in vivo diuretic activity in the housefly (M. domestica). The peptidase-resistant insect kinin analog pQK(pQ)FF[Aib]WG-NH(2) demonstrates a longer internal residence time in the housefly than the native muscakinin (MK), and despite a difference of over 4 orders of magnitude in an in vitro Malpighian tubule fluid secretion assay, is equipotent with MK in an in vivo housefly diuretic assay. Aminohexanoic acid (Ahx) is shown to function as a surrogate for N-terminal Lys, while at the same time providing enhanced resistance to aminopeptidase attack. Peptidaese-resistant insect kinin analogs demonstrate enhanced inhibition of weight gain in larvae of the agriculturally destructive corn earworm moth. Potent peptidase resistant analogs of the insect kinins, coupled with an increased understanding of related regulatory factors, offer promise in the development of new, environmentally friendly pest insect control measures.

Animals↗

PubMed2002

Enhanced oral availability/pheromonotropic activity of peptidase-resistant topical amphiphilic analogs of pyrokinin/PBAN insect neuropeptides.

The peptide bond between active core residues Pro and Arg is the primary site of susceptibility for the pyrokinin/PBAN neuropeptides to insect tissue-bound peptidases, and incorporation of modified Pro residues can enhance resistance to peptidase hydrolysis. An Hyp-containing amphiphilic analog (Hex-FT[Hyp]RLa) is shown to operate as a topically active tissue-bound peptidase-resistant analog of the pyrokinin/PBAN class of insect neuropeptides in adult Heliothis virescens moths. An Oic amphiphilic analog (Hex-FT[Oic]RLa) is ineffective topically, but proves to be a superior tissue-bound, peptidase-resistant pyrokinin/PBAN analog for oral administration; outperforming both the Hyp analog and the orally inactive natural hormone PBAN in the moths. The Oic analog is effective in penetrating an isolated, ligated foregut preparation, but less successful in transmigrating an isolated midgut preparation; whereas the opposite behavior is observed for the Hyp analog. The success of the Oic analog via oral administration may be related to its ability to effectively penetrate the foregut, thereby bypassing the hostile environment of the midgut region.

Administration, Oral↗

PubMed2003

Characterisation of preYvaY export reveals differences in the substrate specificities of Bacillus subtilis and Escherichia coli leader peptidases.

Translocation, processing and secretion of YvaY, a Bacillus subtilis protein of unknown function, were characterised both in B. subtilis and in Escherichia coli. In its natural host B. subtilis, YvaY was transiently synthesised at the end of the exponential growth phase. It was efficiently secreted into the culture supernatant in spite of a calculated membrane spanning domain in the mature part of the protein. In E. coli, despite the high conservation of Sec-dependent transport components, processing of preYvaY was strongly impaired. To uncover which elements of E. coli and B. subtilis translocation systems are responsible for the observed substrate specificity, components of the B. subtilis Sec-system were co-expressed besides yvaY in E. coli. Expression of B. subtilis secA or secYEG genes did not affect processing, but expression of B. subtilis signal peptidase genes significantly enhanced processing of preYvaY in E. coli. While the major signal peptidases SipS or SipT had a strong stimulatory effect on preYvaY processing, the minor signal peptidases SipU, SipV or SipW had a far less stimulatory effect in E. coli. These results reveal that targeting and translocation of preYvaY is mediated by the E. coli Sec proteins but processing of preYvaY is not performed by E. coli signal peptidase LepB. Thus, differences in substrate specificities of E. coli LepB and the B. subtilis Sip proteins provide the bottleneck for export of YvaY in E. coli. Significant slower processing of preYvaY in absence of SecB indicated that SecB mediates targeting of the B. subtilis precursor.

Bacillus subtilis↗