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At least 649 records · Page 36Linked to original sources
PubMed1976

Continuous Proteolysis with a stabilized stabilized protease. I. Chemical stabilization of an alkaline protease.

Due to the loss of enzymatic activity as a function of time, an alkaline protease, selected for the continuous preparation of protein hydrolysates (J. Boudrant and C. Cheftel, Biotechnol. Bioeng., 18,1735, 1976), was chemically stabilized by a simple treatment with glutaraldehyde. Two fractions, soluble and insoluble, were obtained. The activities of these two fractions were measured with casein and N-benzoyl-L-arginine ethyl ester (BAEE) as a function of glutaraldehyde concentration used. It was noted that the insoluble fraction was practically inactive with the first substrate and that the heat stability of the soluble form was likewise enhanced. Molecular weights of these two forms were unchanged, but the uv-spectrum of the soluble form was modified. From amino acid analysis, it appears that this treatment mainly provokes a decrease in lysine content.

Aldehydes↗
PubMed1981

Protease-insensitive sea urchin embryo cell adhesions become protease sensitive in the presence of azide or cytochalasin B.

To understand the nature of the cell adhesions that must be modified during sea urchin embryo primary mesenchyme formation, we are studying the adhesive components of the hatched blastula stage embryo of Strongylocentrotus purpuratus. Pronase treatment conditions have been defined that leave the cells intact and able to recover from the effects of the protease upon its removal. Under these conditions, adhesion of the cells to tissue culture plates is totally eliminated, but cell-cell adhesion formation is only partially inhibited. Analysis of iodinated cell surface proteins indicates that most are affected by the pronase. Further studies of pronase effects found that sodium azide-treated cells are slightly adhesive and that pronase treatment of azide-treated cells totally eliminates cell-cell adhesions.

Animals↗
PubMed1993

Consequences of unbalanced protease in the lung: protease involvement in destruction and local defense mechanisms of the lung.

Complex mechanisms regulate sequestration, retention and migration of neutrophils in the lung. Neutrophils can migrate into the lung without producing significant damage under some circumstances, whereas at other times great structural alteration occurs. A potential explanation lies in the phenomenon of priming, a state of altered responsivity of neutrophils. A wide variety of molecules are able to induce this higher degree of responsiveness including PAF, TNF, GM-CSF, and IL-1. Enhanced cellular responses include secretion, adhesion and synthetic function. Unprimed neutrophils can migrate through lung tissues, secreting but little of their contents, in the context of "normal" inflammatory response. On the other hand neutrophils primed before the emigration phase, injury to the tissue they are migrating through would be likely by virtue of releasing toxic mediators. One of these mediators is neutrophil elastase, a potent protease. It is the purpose of this review to highlight the duality function of neutrophils as (i) one of the bodies highly effective host defense weapons and (ii) mediator of destruction and host defense impairment in the lung by releasing mediators such as neutrophil elastase.

Bronchopulmonary Dysplasia↗
PubMed1975

Human skin proteases: separation and characterization of two alkaline proteases, one splitting trypsin and the other chymotrypsin substrates.

Two alkaline proteases, one splitting preferentially the substrates of chymotrypsin (ATEE) and the other one those of trypsin (BAEE), were separated and partially purified by chromatographic means from human skin extract made in a buffer containing 1.07 mol/1 KC1. The proteins soluble in dilute buffer were removed by a prior extraction. The enzymes could be separated effectively only in the presence of KC1 at a high conc-ntration since large molecular size aggregates or polymers were formed in solutions of low ionic strength. In the presence of 2 mol/1 KC1 the molecular size of the BAEE-hydrolysing enzyme was 120000 and that of the ATEE-hydrolysing enzyme 30000. The ATEE-hydrolysing enzyme was purified by Sephadex G-100 gel filtration and DEAE-cellulose chromatography about 250 fold. It also hydrolysed esters of tryptophane and phenylalanine as well as casein with optimum pH 7.8--8.2. The enzyme was inhibited effectively by LBTI, SBTI and partially by trasylol, TPCK and TLCK, but not by E-600 and SH-modifers. The hydrolysis of ATEE was doubled in the presence of 1 mol/lKCl, NaCl, KBr or NaBr but that of casein was inhibited to some extent. Human serum and alpha-1-antitrypsin inhibited this enzyme but not C1-inactivator. alpha-2-Macroglobulin did not protect if from inhibition by SBTI. The BAEE-hydrolysing enzyme was purified by Sephadex G-100 gel filtration and hydroxylapatite chromatography about 30 fold. It also split other esters of substituted basic amino acids as well as BAPA and histone proteins with optimum pH 7.5--8.2. It was inhibited by Trasylol and TLCK, but not by LBTI, SBTI, OMTI, TPCK, E-600, SH-modifiers, human serum, C1-inactivator or alpha-1-antitrypsin. Neither of these enzymes is exactly similar to any one of the enzymes so far separated from human tissues or fluids.

Acetates↗
PubMed2005

Simultaneous labeling of mast cell proteases and protease mRNAs at the bone-implant interface of aseptically loosened hip implants.

Human mast cells (MC) exhibit two distinct phenotypes based on the protease content of their secretory granules. MC(TC) cells express tryptase, chymase, cathepsin G, and mast cell carboxypeptidase, while MC(T) cells express only tryptase. Both mast cell phenotypes were assessed near regions of osteolysis in uninfected failed joint implants by immunohistochemistry with antibodies to tryptase and chymase, and by in situ hybridization with anti-sense RNA probes for the respective mRNA molecules. Specimens from the interface membrane of 32 aseptically loosened total hip implants were studied, 28 of which had mast cells of the MC(TC) type. Most of these mast cells were aligned along the bone-prosthesis interface adjacent to loosened implants, suggesting involvement in the chronic inflammatory response that leads to bone resorption. Further ultrastructural evidence of mast cells in tissues from failed joint interface membranes was shown by transmission electron microscopy, and detection by staining after magnetic activated cell sorting. The presence of MC at the periprosthetic interface of eroded bone suggests MC degranulation and activity are associated with osteolysis in failed joint prostheses.

Arthroplasty, Replacement, Hip↗
PubMed1998

In vivo Responses of Honey Bee Midgut Proteases to Two Protease Inhibitors from Potato.

Potato protease inhibitors, POT-1 and POT-2, were fed to newly emerged adult honey bees in cages at different doses in either sugar syrup (0.2 or 0.01% w:v) or pollen food (1 or 0.2% w:w). In vivo activities of three digestive endopeptidases (trypsin, chymotrypsin and elastase) and one exopeptidase (leucine aminopeptidase; LAP) were measured after 3 or 8days' exposure of bees to inhibitor. Enzyme activities were significantly lower at day 8 than at day 3, except for elastase, which did not change. POT-2 significantly reduced the activity of all endopeptidases at both timepoints, regardless of the dose level or the medium in which the inhibitor was administered. POT-1 acted in a similar manner, except that 0.01% POT-1 in syrup had no effect on bees. There was no consistent trend in changes in LAP activity. Bees fed either inhibitor at 1% in pollen or at 0.2% in syrup had significantly reduced lifespans, with the effect of the pollen treatment being greater than the syrup treatment. The survival of bees fed POT-1 or POT-2 at 0.2% in pollen or 0.01% in syrup did not differ from the controls.

Journal Article↗
PubMed1999

Melain G, a cysteine protease from green fruits of the bead tree, Melia azedarach: a protease affected by specific amino acids at P3 position.

A protease (melain G) was isolated from the greenish fruits of the bead tree, Melia azedarach var. japonica Makino. Melain G shares 110 identical amino acid residues (50%) with papain, 112 (51%) with actinidain, and 91 (41%) with stem bromelain. From the sites cleaved in the oxidized insulin B-chain and synthetic oligopeptide substrates by melain G, the enzyme preferred small amino acid residues such as Gly or Ser at the P2 position and negatively charged residues such as glutamic or cysteic acid at the P3 position. This is clearly different from the specificity of papain, which prefers the large hydrophobic amino acid residues such as Phe, Val, and Leu at the P2 position. Accordingly, it is presumed that the bottom of the S2 pocket of melain G is shallow due to the presence of a Phe residue, and a bulky P2 substrate (for example Phe residue) is not preferred by the enzyme. Negatively charged residues at the P3 position of substrates well suited the S3 site of melain G for making a salt bridge. It is likely that Arg61 is the S3 position of melain G by analogy with papain.

Amino Acid Sequence↗
PubMed2004

Temperature dependent protease activity and structural properties of human HtrA2 protease.

Human HtrA2 belongs to a new class of oligomeric serine protease, members of which are found in most organisms. Mature HtrA2 is released from mitochondria into the cytosol in response to apoptotic stimuli. In this report, the effect of temperature on proteolytic activity of HtrA2 and related structural properties were investigated. In the range from 25 to 55 degrees C, the proteolytic activity of HtrA2 rapidly increased with temperature, and it drastically decreased at and over 60 degrees C. Structural analysis using far-UV CD spectroscopy and gel filtration revealed no significant change in the secondary structure of HtrA2 from 25 to 70 degrees C, or in the oligomeric size between 25 and 55 degrees C. However, a significant change at the tertiary level, as examined using near-UV CD, was observed for HtrA2 in the range from 25 to 60 degrees C. Differential scanning calorimetry indicated that HtrA2 exhibits a thermal transition beginning at around 61 degrees C. The fluorescence intensity of ANS interacting with HtrA2 decreased with increasing temperature. HtrA2 was found to be able to complement DegP function at 44 degrees C, indicating that HtrA2 could have protective functions in mitochondria.

Circular Dichroism↗
PubMed1995

Packaging of proteases and proteoglycans in the granules of mast cells and other hematopoietic cells. A cluster of histidines on mouse mast cell protease 7 regulates its binding to heparin serglycin proteoglycans.

Mouse mast cell protease 7 (mMCP-7) is a tryptase stored in the secretory granules of mast cells. At the granule pH of 5.5, mMCP-7 is fully active and is bound to heparin-containing serglycin proteoglycans. to understand the interaction of mMCP-7 with heparin inside and outside the mast cell, this trytase was first studied by comparative protein modeling. The "pro" form of mMCP-7 was then expressed in insect cells and studied by site-directed mutagenesis. Although mMCP-7 lacks known linear sequences of amino acis that interact with heparin, the three-dimensional model of mMCP-7 revealed an area on the surface of the folded protein away from the substrate-binding site that exhibits a strong positive electrostatic potential at the acidic pH of the granule. In agreement with this calculation, recombinant pro-mMCP-7 bound to a heparin-affinity column at pH 5.5 and readily dissociated from the column at pH > 6.5. Site-directed mutagenesis confirmed the prediction that the conversion of His residues 8,68, and 70 in the positively charged region into Glu prevents the binding of pro-mMCP-7 to heparin. Because the binding requires positively charged His residues, native mMCP-7 is able to dissociate from the protease/proteoglycan macromolecular complex when the complex is exocytosed from bone marrow-derived mast cells into a neutral pH environment. Many hematopoietic effector cells store positively charged proteins in granules that contain serglycin proteoglycans. The heparin/mMCP-7 interaction, which depends on the tertiary structure of the tryptase, may be representative of a general control mechanism by which hematopoietic cells maximize storage of properly folded, enzymatically active proteins in their granules.

Amino Acid Sequence↗
PubMed2004

Dependence of site-2 protease cleavage of ATF6 on prior site-1 protease digestion is determined by the size of the luminal domain of ATF6.

ATF6 is an endoplasmic reticulum (ER) membrane-anchored transcription factor activated by regulated intramembrane proteolysis in the ER stress response. The release of the cytosolic transcription factor domain of ATF6 requires the sequential processing by the Golgi site-1 and site-2 proteases (S1P and S2P). It has been unclear why S2P proteolysis relies on previous site-1 cleavage. One possibility is that S2P localizes to a different cellular compartment than S1P; however, here we show that S2P localizes to the same compartment as S1P, the cis/medial-Golgi. In addition, we have re-localized S1P and S2P to the ER with brefeldin A and find that the sequential cleavage of ATF6 is reconstituted in the ER. The mapping of the region of ATF6 required for sequential S1P and S2P cleavage showed that short luminal domains resulted in S1P-independent S2P cleavage. The addition of artificial domains onto these short ATF6 luminal domains restored the S1P dependence of S2P cleavage, suggesting that it is the size rather than specific sequences in the luminal domain that determines the S1P dependence of S2P cleavage. These results suggest that the bulky ATF6 luminal domain blocks S2P cleavage and that the role of S1P is to reduce the size of the luminal domain to prepare ATF6 to be an optimal S2P substrate.

Activating Transcription Factor 6↗
PubMed2004

Functional overexpression of gamma-secretase reveals protease-independent trafficking functions and a critical role of lipids for protease activity.

Presenilins appear to form the active center of gamma-secretase but require the presence of the integral membrane proteins nicastrin, anterior pharynx defective 1, and presenilin enhancer 2 for catalytic function. We have simultaneously overexpressed all of these polypeptides, and we demonstrate functional assembly of the enzyme complex, a substantial increase in enzyme activity, and binding of all components to a transition state analogue gamma-secretase inhibitor. Co-localization of all components can be observed in the Golgi compartment, and further trafficking of the individual constituents seems to be dependent on functional assembly. Apart from its catalytic function, gamma-secretase appears to play a role in the trafficking of the beta-amyloid precursor protein, which was changed upon reconstitution of the enzyme but unaffected by pharmacological inhibition. Because the relative molecular mass and stoichiometry of the active enzyme complex remain elusive, we performed size exclusion chromatography of solubilized gamma-secretase, which yielded evidence of a tetrameric form of the complex, yet almost completely abolished enzyme activity. Gamma-secretase activity was reconstituted upon addition of an independent size exclusion chromatography fraction of lower molecular mass and nonproteinaceous nature, which could be replaced by a brain lipid extract. The same treatment was able to restore enzyme activity after immunoaffinity purification of the gamma-secretase complex, demonstrating that lipids play a key role in preserving the catalytic activity of this protease. Furthermore, these data show that it is important to discriminate between intact, inactive gamma-secretase complexes and the active form of the enzyme, indicating the care that must be taken in the study of gamma-secretase.

Amyloid Precursor Protein Secretases↗
PubMed1976

A Ca2+-activated protease possibly involved in myofibrillar protein turnover. Subcellular localization of the protease in porcine skeletal muscle.

A study was done to determine whether the Ca2+-activated muscle protease (CAF) that removes Z disks from myofibrils in the presence of Ca2+ is located in a sedimentable subcellular organelle. Porcine skeletal muscle cells were diced finely with a scalpel and were suspended in 0.25 M sucrose, 4 mM EDTA with a VIRTIS homogenizer. Filtration of the suspended muscle through four layers of cheesecloth removed most of the myofibrils and stromal protein. Nuclear (1,000 gavg for 15 min), mitochondrial-microsomal (50,000 gavg for 60 min), and supernatant fractions were assayed for succinic dehydrogenase, acid ribonuclease, cathepsin D, and CAF activities. Approximately 96% of total succinic dehydrogenase activity, 81% of cathepsin D activity, and 45% of acid ribonuclease activity, but only 14% of total CAF activity, were found in the nuclear and mitochondrial-microsomal fractions. Cathepsin D activity in the nuclear and mitochondrial-microsomal fractions was decreased if assays were done without prior treatment to rupture membranous structures; hence, our cell rupture and homogenization procedures preserved some intact lysosomal organelles. The results indicate that the small amount of CAF activity in the nuclear and mitochondrial-microsomal fractions was due to contamination by supernate and that CAF is not located in a membrane-bounded subcellular particle. Because CAF is active at the intracellular pH and temperature of living skeletal muscle cells and is in direct contact with the cytoplasm of muscle cells, its activity must be regulated by intracellular cellular Ca2+ concentration to prevent continuous and indiscriminate degradation of myofibrils.

Animals↗
PubMed1980

Thermitase, a thermostable serine protease from Thermoactinomyces vulgaris. Classification as a subtilisin-type protease.

Studies on the amino acid composition, chemical modifications, and characterization of the cyanogen bromide cleavage peptides of a thermostable serine protase (thermitase) from Thermoactinomyces vulgaris were performed. The amino acid analysis shows that the enzyme contains a single cysteine and methionine residue. From the amino acid composition as well as a partial sequence determination around the single methionine residue it is concluded that thermitase belongs to the subtilisin-type proteases. The two peptides obtained by cyanogen bromide cleavage were further characterized by amino acid analysis and molecular weight determination yielding 25 000 and 6 000 daltons, respectively. Chemical modification experiments show that in addition to the active site serine and histidine residue the cysteine as well as the methionine residue are essential for activity of the enzyme. The alignment of these amino acids in the polypeptide chain of the thermitase is supposed.

Amino Acid Sequence↗
PubMed1991

Degradation of plasma proteins by the trypsin-like enzyme of Porphyromonas gingivalis and inhibition of protease activity by a serine protease inhibitor of human plasma.

The interaction between Porphyromonas gingivalis culture supernatant and human serum was examined. Hydrolysis of the major serum proteins was thiol-dependent and correlated with the trypsin-like activity of the sample. Transferrin and IgG light chains were less susceptible to degradation than albumin and IgG heavy chains and partially degraded IgG retained antigen-binding capability. Serum inhibited the trypsin-like activity in a fluorimetric assay. The inhibition was shown to be independent of the level of IgG antibody reactive with whole cells of P. gingivalis. Purified preparations of antithrombin III, a serine protease inhibitor, but not alpha 1-antitrypsin nor alpha 2-macroglobulin inhibited the trypsin-like activity in the fluorometric assay.

Antigens, Bacterial↗
PubMed1976

Studies of new intracellular proteases in various organs of rats. Participation of proteases in degradation of ornithine aminotransferase in vitro and in vivo.

Homogenates of the muscle layer of rat small intestine irreversibly inactivated endogenous ornithine aminotransferase at 37 degrees C. Addition to the homogenate of coenzymes and the various keto-acids which act as substrate inhibited conversion of the holoenzyme to the apoenzyme and its subsequent degradation. Addition of protease inhibitors including soybean trypsin inhibitor, chymostatin and phenylmethylsulfonyl fluoride almost completely prevented inactivation of he enzyme. Immunological activity decreased during inactivation of the enzyme, but its rate of decrease was much slower than that of loss of enzyme activity. Antigen-antibody precipitates from homogenates containing inactivated enzyme, were separated by electrophoresis on sodium dodecylsulfate-polyacrylamide gels. In this way breakdown products of the enzyme were found, indicating that the enzyme in homogenates was inactivated by limited proteolysis. These results obtained in vitro support our previous suggestion (1975) of a stepwise mechanism for degradation of pyridoxal enzymes.

Animals↗
PubMedDate not supplied

Plasmodium falciparum: differential sensitivity in vitro to E-64 (cysteine protease inhibitor) and Pepstatin A (aspartyl protease inhibitor).

We investigated the effect of a cysteine proteinase inhibitor (E-64) and an aspartyl proteinase inhibitor (Pepstatin A) on asexual erythrocytic stages of Plasmodium falciparum in culture. These two protease inhibitors showed different patterns of activity. E-64 acted preferentially against trophozoite and schizont stages. After 48 h incubation at high concentrations of E-64 (28, 140, 280 microM), growth was totally abolished and the parasites presented characteristic enlarged food vacuoles. Morphological alterations were also seen after shorter incubation periods (6 h at 28 microM) or 12 h at the inhibitory concentration 50% (12 microM), but an additional culture period (24 h) in inhibitor-free medium allowed normal parasite development, demonstrating a parasitostatic effect. E-64 acts on parasite multiplication; the normal merozoite maturation was altered and the normal reinvasion process partially impaired. Pepstatin A used at the inhibitory concentration 50% (4 microM) killed the parasites before trophozoite development and had a major effect on schizonts maturation. No altered parasite development occurred during an additional culture period without Pepstatin A, demonstrating a parasiticidal effect. E-64 and Pepstatin A used in combination inhibit the parasite growth with a strong synergistic effect.

Animals↗
PubMed2005

Similarities and specificities of fungal keratinolytic proteases: comparison of keratinases of Paecilomyces marquandii and Doratomyces microsporus to some known proteases.

Based on previous screening for keratinolytic nonpathogenic fungi, Paecilomyces marquandii and Doratomyces microsporus were selected for production of potent keratinases. The enzymes were purified and their main biochemical characteristics were determined (molecular masses, optimal temperature and pH for keratinolytic activity, N-terminal amino acid sequences). Studies of substrate specificity revealed that skin constituents, such as the stratum corneum, and appendages such as nail but not hair, feather, and wool were efficiently hydrolyzed by the P. marquandii keratinase and about 40% less by the D. microsporus keratinase. Hydrolysis of keratin could be increased by the presence of reducing agents. The catalytic properties of the keratinases were studied and compared to those of some known commercial proteases. The profile of the oxidized insulin B-chain digestion revealed that both keratinases, like proteinase K but not subtilisin, trypsin, or elastase, possess broad cleavage specificity with a preference for aromatic and nonpolar amino acid residues at the P-1 position. Kinetic studies were performed on a synthetic substrate, succinyl-Ala-Ala-Pro-Phe-p-nitroanilide. The keratinase of P. marquandii exhibited the lowest Km among microbial keratinases reported in the literature, and its catalytic efficiency was high in comparison to that of D. microsporus keratinase and proteinase K. All three keratinolytic enzymes, the keratinases of P. marquandii and D. microsporus as well as proteinase K, were significantly more active on keratin than subtilisin, trypsin, elastase, chymotrypsin, or collagenase.

Amino Acid Sequence↗