Intracellular distribution of neutral proteinases and inhibitors in pig leucocytes. Isolation of two inhibitors of neutral proteinases.

Granule and post-granular-supernatant fractions were obtained from pig leucocyte cells by differential centrifugation in 0.34 M sucrose. Granule extract possesses proteinase activity at acid and at neutral pH. Three groups of neutral and a group of acid proteinases were isolated from granule extracts by chromatography on DEAE-cellulose. In the first group are present elastase-like and plasminogen-activator proteinases, that are inhibited by diisopropylphosphorofluoridate, alpha1-antitrypsin, intracellular leucocyte inhibitor and partly with p-aminomethylbenzoic acid and Trasylol. The second group of neutral proteinases is unstable under the conditions of isolation used the third group of neutral proteinases comprises collagenases that are inhibited by ethylenediamine tetraacetic acid disodium salt, alpha1-antitrypsin and leucocyte inhibitor. The acid proteinases are inhibited only with pepstatin, up to 90%. In the post-granular supernatant was found the acid proteinase activity towards hemoglobin and casein, and non-stable neutral proteolytic activity towards bovine serum albumin and serum gamma globulin. In the post-granular supernatant also the inhibitors of neutral proteinases were found. By gel filtration on Sephadex G-100 and ion-exchange chromatography on CM-cellulose two inhibitors of neutral proteinases were isolated. The majority of the inhibitor capacity (about 80%) of post-granular supernatant was eluted together with ovalbumin (Mr 43000) and the remainder with cytochrome c (12300). These inhibitors inhibit the granule neutral proteinases, acting on all substrates used, but do not inhibit granule acid proteinase. Inhibition effects of post-granular-supernatant inhibitors on trypsin and chymotrypsin were obtained only when bovine serum albumin was used as substrate. Inhibitors of post-granular supernatant are stable at pH 6-8, but unstable in the pH rnage 2-5 and are thermolabile.     

Inhibition of human granulocyte proteinases by a heat and acid-stable proteinase inhibitor from rabbit serum]

Several human granulocyte proteinases sensitive to the thermo- and acid-resistant proteinase inhibitor from rabbit serum (TASPI) were revealed, using TASPI-Sepharose 4B. It was found that TASPI inhibits the following human granulocyte proteinases: granules-localized kininogenase and chymotrypsin-like kininase (serine proteinases), elastase-like proteinase and benzoyl arginine ethyl ester esterase, as well as chymotrypsin-like kininase from the post-granule supernatant. These enzymes were compared to known granulocyte proteinases. Some carboxylic kininogenase sensitive to TASPI was identified in the granulocyte membrane debris fraction. The capability to inhibit neutral kininogenase suggests that TASPI is a first natural proteinase inhibitor, which can differentiate granulocyte and blood plasma kininogenases. Using trypsin-Sepharose 4B in the granulocyte post-granule supernatant, the acid-resistant trypsin and chymotrypsin inhibitor was identified. The data obtained are indicative of an antiinflammatory function of TASPI in mammals.     

Purification of Bacillus mesentericus proteolytic enzymes by affinity chromatography

By means of affinity chromatography on Ovomucoid-Sepharose two proteinases hydrolyzing casein and elastin were isolated from the supernatant of the Bacillus mesentericus culture medium. The activity yield of proteinases was 100%. The characteristics of the purified enzymes were studied. It is demonstrated that B. mesentericus possesses several proteinases.     

Isolation and characterization of inhibitors of neutral proteinases from spleen

Two different types of neutral proteinase inhibitors were isolated from postmicrosomal supernatant of bovine spleen. Inhibitor A with molecular weight 40,000 inhibits elastases and chymotrypsin-like neutral proteinases from bovine spleen, whereas inhibitor B with estimated molecular weight 20 000 inhibits only chymotrypsin-like neutral proteinase.     

Isolation and properties of extracellular proteinases of Penicillium marneffei

Penicillium marneffei is a dimorphic fungus native to Southeast Asia. Disease caused by this organism, until recently a very rare condition, has increased dramatically in parallel with the increase in the number of individuals in the region immunocompromised by AIDS and other conditions. While much research has been performed on the control of dimorphic switching in P. marneffei, there is a relative dearth of information regarding the proteinases secreted by this pathogen. Our laboratory has purified and characterized two proteinases produced by this organism in liquid culture and cloned the gene of a third. Both the recombinant enzyme expressed from the cloned gene and one of those purified from culture supernatants have been identified as members of the eqolisin family, a group of pepstatin-insensitive acid proteinases. The other enzyme purified from a culture supernatant is a serine proteinase with activity in the neutral pH range. These enzymes appear to be differentially expressed, depending on culture conditions.     

Proteolytic activation can produce a phosphatidylinositol phosphodiesterase highly sensitive to Ca2+

The phosphatidylinositol phosphodiesterase of rat brain shows little activity under conditions likely to pertain in vivo (neutral pH and micromolar Ca(2+) concentrations). A short incubation of a brain supernatant with trypsin, or a longer pre-incubation of the supernatant alone, produce new forms of the enzyme, which are active under such conditions. A possible role of receptor-linked proteinases in initiating phosphatidylinositol catabolism is discussed.     

Activation of astrocytic lysosomal proteinases by factors released by mononuclear leukocytes

Lysosomal proteinases are increased in the tissue lesions of experimental allergic encephalomyelitis and have been implicated in the degradation of myelin proteins. The cellular origins of the increased proteinases are not known but reactive astrocytes found in areas of increased activity are candidate cells. To evaluate the potential of astrocytes as the source of these proteinases, cathepsin B (CB) and cathepsin D (CD) levels were measured in lysates of cultured astrocytes from neonatal rats. Because astrocytes are activated by inflammatory mediators in demyelinating lesions the effect of activation on proteinase levels was examined. Culture supernatants from mononuclear leukocytes stimulated with either concanavalin A or phytohemagglutinin (PHA) induced significant increases in the astrocytic proteinases. Neither PHA alone, interleukin-1, interleukin-2, nor gamma-interferon induced significant increases. Fractions of the supernatant from PHA stimulated mononuclear leukocytes were tested and activity was found in fractions corresponding to a molecular weight of 45–50,000. These studies demonstrate that astrocytes contain significant amounts of CB and CD activity which can be increased by a factor or factors released by activated mononuclear leukocytes.Preliminary results presented at the 18th annual meeting of the Society for Neuroscience, Toronto, Canada, Nov. 14, 1988.     

Inhibitor of trypsin and chymotrypsin in cultures of HeLa cells.

An inhibitor of trypsin and chymotrypsin with apparent molecular weight of 68 000 and a mobility similar to alpha1-globulin on polyacrylamide gel electrophoresis, was isolated from serum-free supernatant preparations from HeLa cells. Immunoelectrophoresis assays indicated that the inhibitor differed serologically from known inhibitors of serine proteinases in plasma and urine but shared antigenic determinants with an unidentified protein in these body fluids and with an inhibitor recently isolated from cultures of lung.     

A comparison of secretory proteinases from different strains of Candida albicans

Randomly selected strains of Candida albicans were grown with bovine serum albumin (BSA) as a single nitrogen source. From all strains tested, culture supernatant contained carboxyl proteinase (E.C.3.4.23) as has been shown that with hemoglobin as a substrate and by specific inhibition with pepstatin-A. According to the separation pattern of BSA fragments, secretory proteinases from C. albicans belong to at least three groups. We have purified the partially proteolytic enzyme of strain 113 and have compared its properties with those of the totally proteolytic enzyme of strain CBS 2730. Both enzymes have virtually identical molecular weight (ca. 44,000) and cross-react immunologically; they differ in pH optimum, isoelectric point, substrate specificity, and resistance against alkali. IgG1, which is the prevalent immunoglobulin of human serum, was not cleaved by enzyme 113. Immunoglobulins A1, A2 and secretory component were cleaved by both enzymes, which points to a role of the secretory proteinases in the persistence of yeasts on mucous membranes. Differences in the course of alkaline denaturation indicate that only a fraction of strain-specific proteinases is capable to convey long-range effects in the host.     

Biochemical,morphological and cytochemical studies of enhanced autolysis ofSaccharomyces cerevisiae

Biochemical aspects of induced autolysis ofSaccharomyces cerevisiae were observed in the presence of various physical and chemical enhancers of autolysis (increased temperature, changes of pH, NaCl, ethanol, fresh autolyzate). Direct assays of proteinases, nucleases, glucanases and acid phosphatases in homogenized autolyzed cells were performed. In addition, the degradation products of proteins, nucleic acids, polysaccharides and phosphate from phosphorylated compounds were determined in the supernatant of autolyzate after centrifugation. These results suggested that the inducers affected transport processes and that they had mostly negative effects on the activities of the above-mentioned enzymes.     

Studies on the Proteolytic Enzymes of Thermophilic Streptomyces

Proteolytic enzymes derived from thermophilic streptomyces sp. strain 1689 were purified and some properties were studied. A 8-fold purification was obtained from the culture supernatant by ammonium sulfate fractionation, acetone precipitation, and chromatography on CM-Sephadex. Two proteinases of almost identical properties were fractionated on CM-Sephadex chromatography. The purified preparations appeared to be homogeneous on ultracentrifugation. The optimum pH for proteolytic activity on casein was found to be pH 10.6~10.8. The stability was considerably increased by the addition of Ca⁺⁺, and the proteinases exhibited d relatively high thermal stability. Enzyme activity was inhibited by oxidizing agents, PCMB, potato inhibitor, DFP, and heavy metal ions. Na⁺, K⁺, Mg⁺⁺, and Fe⁺⁺ showed an activating effect.     

Molecular cloning, sequencing, expression of Chinese sturgeon cystatin in yeast Pichia pastoris and its proteinase inhibitory activity

Cystatin, a superfamily of cysteine proteinase inhibitor of cathepsins and other cysteine proteinases, is widely distributed in animal tissues and body fluids. Although considerable attention has been given to mammalian and avian cystatins, little is known about cystatins from other vertebrates. In this study, a cDNA coding for Chinese sturgeon (Acipenser sinensis) cystatin was isolated and characterized. The corresponding mature cystatin peptide cDNA is 336 nucleotides long and encodes a protein of 112 amino acids. Sequence comparison showed that the cloned cystatin was a homolog of the mammalian Family II cystatin. The cystatin cDNA of Chinese sturgeon was subcloned into yeast expression vector pPICZalphaA and transformed into Pichia pastoris GS115 strain. After methanol induction, SDS-PAGE analysis of the culture supernatant indicated that the yield of recombinant cystatin was about 215 mg/l medium supernatant in shaking-flask fermentation medium, accounting for 73.6% of the total supernatant secreted proteins. Our data also showed that the recombinant cystatin is active in inhibiting the protease activity of papain and cathepsin B. Heat stability of the recombinant cystatin was also measured.     

Efficient Production of Casoxin D,a Bradykinin Agonist Peptide Derived from Human Casein,by Bacillus brevis

We efficiently produced a small peptide by the host-vector system using Bacillus brevis as a host. DNA encoding the physiologically functional casoxin D, composed of seven amino acids, was ligated in tandem. An expression-secretion vector containing DNA, which codes for a fusion protein of epidermal growth factor-casoxin D pentamer, was constructed. B. brevis transformed with this plasmid produced about 0.5 g/liter of the fusion protein in the culture supernatant. The fusion protein was purified with ammonium sulfate fractionation from the supernatant and digested with two kinds of proteinases. A peptide well separated by high pressure liquid chromatography was identified as biologically active casoxin D.     

Activation of hepatic branched-chain 2-oxoacid dehydrogenase by rat liver cytosolic supernatant

Hepatic branched-chain 2-oxoacid dehydrogenase is inactivated by nutritional alterations. Reactivation occurs during preincubation of intact mitochondria in the presence of rat liver cytosolic supernatant. Cytosolic supernatant contains two factors capable of reactivating the enzyme. On gel-filtration (Sephadex G-100), one factor (AF1) elutes in the molecular range of 35,000-40,000 and the other factor (AF2) elutes slightly later than inorganic phosphate. AF2 is stable against heat denaturation and treatment with proteinases. It is destroyed by alkaline phosphatase and in the presence of Ap5A, atractyloside, CaCl2 and NaF its stimulatory effect on branched-chain 2-oxoacid dehydrogenase activity is abolished. Inhibition of activation by NaF suggests that a phosphatase might be involved in the activation process.     

Safety issues of Lactobacillus bulgaricus with respect to human gelatinases in vitro

In oral medicine and dentistry probiotics have shown promising results in controlling dental diseases and yeast infections. This study was made to investigate the effect of eight strains of Lactobacillus bulgaricus and their effects on human matrix metalloproteinase-9 (MMP-9). The hypothesis was that these bacteria used in yoghurt production for centuries are not proteolytic and thus can be safely used in the development of probiotic preparations. Bacterial cell fractions and supernatant specimens were prepared and studied with gelatinase zymography and MMP-9 activation was assessed by immunoblotting. The effect of synthetic MMP inhibitors and a serine protease inhibitor (Pefabloc) on bacterial proteinases was studied with zymography. The results showed very low gelatinolytic activity. There was a slight difference between the supernatant and cell fractions so that the supernatant specimens produced weak gelatinolytic bands in zymography while hardly anything was seen in the cell fraction series. The tested synthetic MMP inhibitors and Pefabloc did not affect the proteolytic activity of the lactobacilli strains. The lactobacilli did not seem to induce the conversion of proMMP-9 to its active form. Consequently, our study hypothesis was confirmed and the studied Lactobacillus strains are not likely to degrade host tissue components.     

A bacterial factor induces changes in cysteine proteinase forms in the cellular slime mould Dictyostelium discoideum.

The electrophoretic pattern of cysteine proteinases in axenically grown myxamoebae of Dictyostelium discoideum can be altered by the addition of either Gram-negative (Klebsiella aerogenes, Escherichia coli) or Gram-positive (Micrococcus lysodeikticus, Bacillus subtilis) bacteria to the culture. No changes occurred, however, if either yeast or latex beads were used in place of bacteria. The changes involved the simultaneous loss of proteinases characteristic of the axenic cells (the A-forms) and the acquisition of those found in cells which have been grown on bacteria (the B-forms). Using K. aerogenes the conversion was complete within 4 h. Extracellular proteinase activity was unaffected during this period. After the D. discoideum cells had been lysed, no equivalent change in proteinase band pattern could be produced either by prolonged incubation of cell extracts or by treatment with proteinases. An identical conversion could be induced in cultures of myxamoebae by a factor, cysteine proteinase converting factor (CPCF), present in the 15,000 g supernatant of a sonicated suspension of K. aerogenes. CPCF was macromolecular, as demonstrated by both ultrafiltration and gel filtration, acid-precipitable, but was soluble in ethanol or alkali. Its activity was unaffected by treatment with trypsin. The results suggested that CPCF might be a component of the bacterial cell wall, and since its activity was affected by lysozyme treatment, peptidoglycan is implicated. The results can be interpreted in terms of a novel nutrient-dependent post-translational change which affected most of the cysteine proteinases present in D. discoideum myxamoebae.     

Increased activities of liver cathepsins T and D in carbon tetrachloride-treated rats

Changes in activities of a new proteinase cathepsin T as well as some other lysosomal acid proteinases and hydrolases were examined in liver homogenate from rats treated with a single hepatotoxic dose of carbon tetrachloride. The most striking changes were several-fold increases of liver cathepsin T and D activities over their levels in untreated rats 3 days after administration of the agent to rats. Increase of cathepsin T was greater than that of cathepsin D at all doses of the hepatotoxin examined. The activities of N alpha-benzoyl-DL-arginine 2-naphthylamide hydrolase, acid phosphatase, beta-galactosidase and beta-glucuronidase in poisoned rat liver were unchanged or only slightly increased. Cathepsin T and D activities were less enhanced in mitochondrial lysosomal fractions than in the homogenate, and were greatly elevated in the supernatant fractions of liver from the treated rats. As judged from the molecular weights, the elevated activities of cathepsins T and D in the treated rat liver could be attributable to the two cathepsins themselves and not to other proteinases. Administration to rats of other hepatotoxic agents, thioacetamide and dimethylnitrosamine, also induced the elevation of the two cathepsin activities in liver, but on partial hepatectomy the activities of liver cathepsins T and D did not show such marked increases. Nonparenchymal liver cell fractions were responsible for almost all the increased activities of liver cathepsins T and D. It is possible that cathepsins T and D play a role in the heterolytic breakdown of hepatocyte molecules following CCl4 poisoning.     

Substrate Specificity and Salt Inhibition of Five Proteinases Isolated from the Pyloric Caeca and Stomach of Sardine

To elucidate the mechanism of hydrolysis of fish muscle proteins by fish proteinases in fish sauce production, each pure preparation of three alkaline proteinases and two acid proteinases from sardine was tested for its ability to hydrolyze various proteins and its stability in the presence of 0 to 25% of NaCl. Each of the alkaline proteinases hydrolyzed casein more rapidly than other proteins. A major alkaline proteinase (III) hydrolyzed sarcoplasmic protein from sardine 5-times faster than other alkaline proteinases. Each of two acid proteinases hydrolyzed hemoglobin and myoglobin more rapidly than the other proteins. After preincubation with 25% NaCl, an alkaline proteinase (III) and an acid proteinase (II) were stable although the other proteinases became unstable. The two proteinases, alkaline proteinase III and acid proteinase II, were also stable for three months after the beginning of fish sauce production. The proteolytic activity of each of alkaline and the acid proteinases was strongly inhibited by more than 15% NaCl; however, minimum inhibition was observed when sardine muscle proteins were used as the substrate.     

Differentiation of Staphylococcal and Micrococcal Proteinases by Electrophoresis

The electrophoretic separation of the proteinases produced by staphylococci and micrococci was studied in four buffers. The duration of electrophoresis was based on the migration of a marker dye for a predetermined distance. The migration distances of the enzymes and dye were measured, and enzyme-dye values were calculated. A comparison of enzyme-dye values showed that complete separation of eight serologically different proteinases did not occur in any one buffer; however, in most instances, their relative order of migration was the same in all buffers. Certain strains of Staphylococcus epidermidis produced two proteinases that were different serologically as well as electrophoretically. Staphylococcus aureus strains, on the other hand, produced up to four proteinases that were serologically the same. The proteinases of staphylococci and micrococci can be best characterized by both electrophoretic and serological methods.     

Localization and characterization of hemoglobin-degrading aspartic proteinases from the malarial parasite Plasmodium falciparum.

Three hemoglobin-degrading proteinases were partially purified from food vacuoles isolated from trophozoite-stage forms of the malarial parasite Plasmodium falciparum. Two of the proteinases (M1 and M2) were solubilized by repeated sonication. The remaining proteinase (M3) was solubilized by treatment of the particulate fraction with taurocholic acid, suggesting that proteinase M3 is a membrane-bound proteinase whereas proteinases M1 and M2 are weakly associated with parasite membrane. The location of these proteinases suggests that they may participate in the digestion of host cytosolic protein. After partial purification, but not before, proteinases M1, M2 and M3 are highly sensitive to pepstatin, supporting their designation as aspartic proteinases. These aspartic proteinases show broad specificity for protein substrates. Native hemoglobin, acid denatured hemoglobin and oxidatively damaged hemoglobin are comparable substrates. Hemoglobin within the food vacuole was shown to be primarily native hemoglobin. Chemical modification studies indicate that these three aspartic proteinases have similar properties. The peptide maps from degradation of hemoglobin, however, suggest that aspartic proteinases M1, M2 and M3 are distinct proteinases.