Larval development and proteolytic activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) exposed to different soybean protease inhibitors.

Anticarsia gemmatalis represents a relevant factor for lowering soybean and other legume crop productivities. Protease inhibitors affect protein degradation and reduce the availability of amino acids, impairing the development and survival of insect pests. To evaluate the possible use of proteinaceous protease inhibitors in the management of this pest, the activities of midgut proteases and the growth and development of A. gemmatalis larvae exposed to soybean Bowman-Birk trypsin-chymotrypsin inhibitor (SBBI) and soybean Kunitz trypsin inhibitor (SKTI) were determined. The survival curves obtained using Kaplan-Meier estimators indicated that SKTI and SBBI stimulated larval survival. However, the development of A. gemmatalis was delayed, and prepupal weight decreased in the presence of both inhibitors. The results showed that SKTI and SBBI inhibited the trypsin-like and total proteolytic activities of larvae on the 12th day after eclosion. On the 15th day after eclosion, larvae exposed to SKTI increased the activities of trypsin and total proteases. Although SKTI and SBBI did not affect the survival of the insect, they had effects on midgut proteases in a stage wherein A. gemmatalis fed voraciously, increased the larval cycle, and decreased prepupal weight. These findings provide baseline information about the potential of proteinaceous protease inhibitors to manage the velvetbean caterpillar, avoiding chemical pesticides.

The impaired viability of prostate cancer cell lines by the recombinant plant kallikrein inhibitor.

BACKGROUND: Kallikreins play a pivotal role in establishing prostate cancer. RESULTS: In contrast to the classical Kunitz plant inhibitor SbTI, the recombinant kallikrein inhibitor (rBbKIm) led to prostate cancer cell death, whereas fibroblast viability was not affected. CONCLUSION: rBbKIm shows selective cytotoxic effect and angiogenesis inhibition against prostate cancer cells. SIGNIFICANCE: New actions of rBbKIm may contribute to understanding the mechanisms of prostate cancer. Prostate cancer is the most common type of cancer, and kallikreins play an important role in the establishment of this disease. rBbKIm is the recombinant Bauhinia bauhinioides kallikreins inhibitor that was modified to include the RGD/RGE motifs of the inhibitor BrTI from Bauhinia rufa. This work reports the effects of rBbKIm on DU145 and PC3 prostate cancer cell lines. rBbKIm inhibited the cell viability of DU145 and PC3 cells but did not affect the viability of fibroblasts. rBbKIm caused an arrest of the PC3 cell cycle at the G0/G1 and G2/M phases but did not affect the DU145 cell cycle, although rBbKIm triggers apoptosis and cytochrome c release into the cytosol of both cell types. The differences in caspase activation were observed because rBbKIm treatment promoted activation of caspase-3 in DU145 cells, whereas caspase-9 but not caspase-3 was activated in PC3 cells. Because angiogenesis is important to the development of a tumor, the effect of rBbKIm in this process was also analyzed, and an inhibition of 49% was observed in in vitro endothelial cell capillary-like tube network formation. In summary, we demonstrated that different properties of the protease inhibitor rBbKIm may be explored for investigating the androgen-independent prostate cancer cell lines PC3 and DU145.

New properties of the soybean trypsin inhibitor: Inhibition of human neutrophil elastase and its effect on acute pulmonary injury.

Seeds from legumes including the Gilcine max are known to be a rich source of protease inhibitors. The soybean Kunitz trypsin inhibitors (SKTIs) have been well characterised and have been found to exhibit many biological activities. However their effects on inflammatory diseases have not been studied to date. In this study, SKTI was purified using anion exchange chromatography using a Resource Q column. The purified protein was able to inhibit human neutrophil elastase (HNE) and bovine trypsin. Purified SKTI inhibited HNE with an IC(50) value of 8mug or 0.3nM. At this concentration SKTI showed neither cytotoxic nor haemolytic effects on human blood cell populations. SKTI showed no deleterious effects on organs, blood cells or the hepatic enzymes ALT and AST in the mouse model of acute systemic toxicity. Human neutrophils incubated with SKTI released less HNE than control neutrophils when stimulated with PAF or fMLP (83.1% and 70% respectively). These results showed that SKTI affected both pathways of elastase release by PAF and fMLP stimuli, suggesting that SKTI is an antagonist of fMLP/PAF receptors. In an in vivo mouse model of LPS acute lung injury, SKTI significantly suppressed the inflammatory effects caused by elastase in a dose-dependent manner. Histological sections stained by hematoxylin/eosin confirmed this decrease in inflammation. These results showed that SKTI could be used as a pharmacological agent for the therapy of many inflammatory diseases.

Peltophorum dubium and soybean Kunitz-type trypsin inhibitors induce human Jurkat cell apoptosis.

Plants constitute an important source of compounds which can induce apoptosis in a variety of cells. Previously, we reported the isolation of a trypsin inhibitor from Peltophorum dubium seeds (PDTI). This inhibitor, as well as soybean trypsin inhibitor (SBTI), both belonging to the Kunitz family, have lectin-like properties and trigger rat lymphoma cell apoptosis. In the present study, we demonstrate for the first time that PDTI and SBTI induce human leukemia Jurkat cell death. Induction of apoptosis was confirmed by flow cytometry after propidium iodide labeling of apoptotic nuclei, showing a considerable increase of the sub G(0)/G(1) fraction, with no cell cycle arrest. With the purpose of gaining insight into the signaling pathways involved, we investigated the activation of caspases and the effect of caspase inhibitors, and showed caspases-3 and -8-like activation by PDTI or SBTI-treatment. Consistent with these results, pan caspase inhibitor and caspase-8 inhibitor protected Jurkat cells from apoptosis. However, there was no caspase-9 activation, confirmed by the failure of caspase-9 inhibitor to prevent cell death. No significant release of cytochrome c from mitochondria was detected suggesting that the intrinsic mitochondrial pathway is not predominant in the apoptotic process. On the other hand, recruitment of Fas-associated death domain (FADD) to the cell membrane indicates the involvement of this adaptor protein in PDTI- and SBTI-induced apoptosis in Jurkat cells. Furthermore, human peripheral lymphocytes, either stimulated with phytohemagglutinin or not, are also susceptible to viability decrease induced by these inhibitors.

Digestive enzymes during development of Ceratitis capitata (Diptera:Tephritidae) and effects of SBTI on its digestive serine proteinase targets.

The digestive system of Ceratitis capitata was characterized during its larval development and in the insect stage. Disaccharidases against maltose and sucrose were more evident in the 2nd and 3rd day of larval development and in the adult stage, respectively. Glycosil-hydrolyses with higher specific alpha-galactosidasic and beta-galactosidasic activities were detected in the 2nd and 3rd day of the larval stage, respectively. Specific proteolytic activities against azocasein showed an increase in the 4th and 5th day of the larval stage and in the adult stage. Specific hemoglobin activities were constant between 2nd and 6th day of the larval stage. The larvae used mainly serine proteinases, such as trypsin/chymotrypsin, and the adult insects only chymotrypsin-like enzymes in their digestive process. Two serine proteinases were separated from zymogram between the 4th and 5th day of larval development and in the adult stage. Effect of soybean trypsin inhibitor (SBTI, a serine proteinase inhibitor) on development of C. capitata was examined by bioassay. C. capitata was susceptible to SBTI which affected larval mass at ED50 3.01%.

Isolation and characterization of trypsin from pyloric caeca of Monterey sardine Sardinops sagax caerulea.

Trypsin from pyloric caeca of Monterey sardine was purified by fractionation with ammonium sulfate, gel filtration, affinity and ionic exchange chromatography. Fraction 102, obtained from ionic exchange chromatography, generated one band in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing. The molecular mass of the isolated trypsin was 25 kDa and showed esterase-specific activity on Nalpha-p-tosyl-L-arginine methyl ester (TAME) that was 4.5 times greater than amidase-specific activity on N-benzoyl-L-arginine-p-nitroanilide. The purified enzyme was partially inhibited by the serine-protease phenyl-methyl-sulfonyl fluoride (PMSF) inhibitor and fully inhibited by the soybean trypsin inhibitor (SBTI) and benzamidine, but was not inhibited by the metallo-protease inactivator EDTA or the chymotrypsin inhibitor tosyl-L-phenylalanine chloromethyl-ketone. The optimum pH for activity was 8.0 and maximum stability was observed between pH 7 and 8. A marked loss in stability was observed below pH 4 and above pH 11. Activity was optimum at 50 degrees C and lost activity at higher temperatures. The kinetic trypsin constants K(m) and k(cat) were 0.051 mM and 2.12 s(-1), respectively, while the catalytic efficiency (k(cat)/K(m)) was 41 s(-1) mM(-1). General characteristics of the Monterey sardine trypsin resemble those of trypsins from other fish, especially trypsins from the anchovy Engraulis japonica and Engraulis encrasicholus and the sardine Sardinops melanostica.

Effects of soybean Kunitz trypsin inhibitor on the cotton boll weevil (Anthonomus grandis).

The cotton boll weevil, Anthonomus grandis, is an economically important pest of cotton in tropical and subtropical areas of several countries in the Americas, causing severe losses due to their damage in cotton floral buds. Enzymatic assays using gut extracts from larval and adult boll weevil have demonstrated the presence of digestive serine proteinase-like activities. Furthermore, in vitro assays showed that soybean Kunitz trypsin inhibitor (SKTI) was able to inhibit these enzymes. Previously, in vivo effects of black-eyed pea trypsin chymotrypsin inhibitor (BTCI) have been demonstrated towards the boll weevil pest. Here, when neonate larvae were reared on an artificial diet containing SKTI at three different concentrations, a reduction of larval weight of up to 64% was observed for highest SKTI concentration 500 microM. The presence of SKTI caused an increase in mortality and severe deformities of larvae, pupae and adult insects. This work therefore represents the first observation of a Kunitz trypsin inhibitor active in vivo and in vitro against A. grandis. Bioassays suggested that SKTI could be used as a tool in engineering crop plants, which might exhibit increased resistance against cotton boll weevil.

Characterization of a Kunitz trypsin inhibitor with one disulfide bridge purified from Swartzia pickellii.

Swartzia pickellii is a Leguminosae that belongs to the Caesalpinioideae sub-family the Swartzia pickellii Trypsin Inhibitor (SWTI), a serine proteinase inhibitor was isolated from its seeds. SWTI is a single polypeptide chain protein and it's structure has 174 amino acid residues, it homologous to other Kunitz plant inhibitors, however shows some major differences: it contains only one disulfide bridge, instead two which are usually found in plant Kunitz inhibitors, and the SWTI reactive site does not contain the usual Arg or Lys residues at the putative reactive site (position 65). A glycosylation site was detected at Asn38 with 1188 kDa carbohydrate portion. The primary structure micro heterogeneity was found combining the sequence determination and mass spectrometry. Three forms of SWTI were actually defined: two glycosylated forms a 20,204 kDa (Arg 165) and 20,185 kDa (His 165) and one deglycosylated form 19,016 kDa (Arg 165), all of them contain a Met residue at position 130.

Synthetic peptides and fluorogenic substrates related to the reactive site sequence of Kunitz-type inhibitors isolated from Bauhinia: interaction with human plasma kallikrein.

We have previously described Kunitz-type serine proteinase inhibitors purified from Bauhinia seeds. Human plasma kallikrein shows different susceptibility to those inhibitors. In this communication, we describe the interaction of human plasma kallikrein with fluorogenic and non-fluorogenic peptides based on the Bauhinia inhibitors' reactive site. The hydrolysis of the substrate based on the B. variegata inhibitor reactive site sequence, Abz-VVISALPRSVFIQ-EDDnp (Km 1.42 microM, kcat 0.06 s(-1), and kcat/Km 4.23 x 10(4) M(-1) s(-1)), is more favorable than that of Abz-VMIAALPRTMFIQ-EDDnp, related to the B. ungulata sequence (Km 0.43 microM, kcat 0.00017 s(-1), and kcat/Km 3.9 x 10(2) M(-1) s(-1)). Human plasma kallikrein does not hydrolyze the substrates Abz-RPGLPVRFESPL-EDDnp and Abz-FESPLRINIIKE-EDDnp based on the B. bauhinioides inhibitor reactive site sequence, the most effective inhibitor of the enzyme. These peptides are competitive inhibitors with Ki values in the nM range. The synthetic peptide containing 19 amino acids based on the B. bauhinioides inhibitor reactive site (RPGLPVRFESPL) is poorly cleaved by kallikrein. The given substrates are highly specific for trypsin and chymotrypsin hydrolysis. Other serine proteinases such as factor Xa, factor XII, thrombin and plasmin do not hydrolyze B. bauhinioides inhibitor related substrates.

COX and LOX eicosanoids modulate platelet activation and procoagulation induced by two murine cancer cells.

Involvement of arachidonic acid cyclooxygenase (COX) and lipoxygenase (LOX) metabolites in platelet aggregation and coagulation induced by two varieties of cancer cells of murine transplantable tumors was studied. A lung alveolar carcinoma (LAC) and a fibrosarcoma (FS), induced platelet aggregation and plasma coagulation (P<0.05). Pretreatment of both tumor lines with a COX inhibitor did not block the tumor cell induced platelet aggregation (TCIPA). COX [12(S)-HTT] and LOX [12(S)-HETE], metabolites of washed platelets (WP), alone or co-incubated with LAC or FS cells, were analyzed. We observed higher 12(S)-HETE release with respect to 12(S)HHT when WP were co-incubated with LAC cells. With both neoplastic cell (NC) lines prothrombin time (PT) was shortened. Pretreatment of NC with iodoacetic acid, soybean trypsin inhibitor or Factor X-deficient plasma increased the PT. These results indicate that AA metabolites play a role on the procoagulation and platelet aggregation induced by mesenchymal and epithelial murine cancers.

Functional interactions between sulphated polysaccharides and proacrosin: implications in sperm binding and digestion of zona pellucida.

Acrosin is a serine protease located within mammalian acrosome as inactive proacrosin. Sulphated polymers bind to proacrosin and acrosin, to a domain different from the active site. Upon binding, these polymers induce proacrosin activation and some of them, such as fucoidan, inhibit sperm binding to the zona pellucida. In this work we have studied the interaction of solubilised zona pellucida glycoproteins (ZPGs), heparin and ARIS (Acrosome Reaction Inducing Substance of Starfish) with boar and human acrosin. We have found that ARIS, solubilised ZPGs and fucoidan, but not heparin, inhibit the binding of the monoclonal antibody against human acrosin C5F10 to boar or human proacrosin. These results suggest that fucoidan, solubilised ZPGs and ARIS bind to a related domain on the proacrosin surface. Moreover, ARIS was able to induce human proacrosin activation. On the other hand, neither ARIS nor heparin from porcine intestinal mucosa or bovine lung induced hamster sperm acrosome reaction or sperm motility. Recent data showed that acrosin is involved in dispersal of the acrosomal matrix after acrosome reaction. Thus, the control of the ZPG glycan chains over proacrosin activation may regulate both sperm penetration rate and limited proteolysis of zona pellucida proteins.

Proteolytic activity of rabbit perivitelline spermatozoa.

Acrosin, an acrosomal serine protease, has been associated with binding of spermatozoa and their penetration through the zona pellucida. This study was aimed at determining whether the remaining proacrosin/acrosin system on rabbit perivitelline spermatozoa still has proteolytic activity and whether this activity is involved in further penetration of unfertilised rabbit eggs. Eight hundred and sixty-five rabbit perivitelline spermatozoa were evaluated by the gelatin-substrate film technique for the detection of acrosin on individual spermatozoan. Fifteen per cent of the studied spermatozoa showed small digestion halos on the gelatin film. The proteolytic activity of rabbit perivitelline spermatozoa was inhibited in the presence of 1 mg/ml of soybean trypsin inhibitor (SBTI) or with 20 micrograms/ml of a mixture of the monoclonal anti-proacrosin/acrosin antibody. In vitro fertilisation occurred in 21.8% of rabbit oocytes co-incubated with perivitelline spermatozoa and was completely inhibited when oocytes were incubated with 600 micrograms/ml of a mixture of three anti-acrosin monoclonal antibodies (ACRO-A8C10, ACRO-C2B10 and ACRO-C5F10). Inseminations in the presence of anti-cholera monoclonal antibody (irrelevant to spermatozoa) resulted in 17.6% fertilisation. These results support the idea that the residual proacrosin/acrosin system in perivitelline spermatozoa might be involved in spermatozoal binding and/or second penetration through the zona pellucida.

Proteinase inhibitor from Stichodactyla helianthus: purification, characterization and immobilization.

A Kunitz type proteinase inhibitor was isolated from extracts of the sea anemone Stichodactyla helianthus. The purification procedure comprises treatment with trichloroacetic acid followed by affinity chromatography on trypsin-Sepharose and gel filtration on Sephadex G-50 or ion exchange chromatography on CM-cellulose. The major inhibitor (isoelectric point 8.4) is a small protein consisting of 55 amino acid residues lacking tryptophan and methionine, with a molecular weight of 6110 (FAB-MS). The amino acid sequence and the structure in solution (NMR) were determined. The inhibitor exhibits a broad specificity for serine, cysteine and aspartic proteinases. Reactors were prepared with immobilized inhibitor in different supports (Sepharose, cellulose, and silica gel) to be employed in the elimination of undesirable proteinases and the purification of different kinds of proteolytic enzymes.

Sucralphate in the prevention of acute gastric lesions induced by ischemia-reperfusion.

The role of sucralphate in prevention of acute gastric injuries and its comparison with free radical blockers such as allopurinol, soybean trypsin inhibitor and superoxidase dismutase in the ischemia-reperfusion model by total occlusion of the coeliac artery in Wistar rats, was studied. The gross gastric mucosal necrotic area was 80%. In contrast with the antioxidant drugs the necrotic area attained was between 7 to 15%, while with sucralphate, an antioxidant-cytoprotective drug that enhances the gastric defensive barrier, the prevention of the secondary aggression induced by free radicals was more important.

Axonal sprouting induced in the sciatic nerve by the amyloid precursor protein (APP) and other antiproteases.

Protease inhibition is the mechanism by which some trophic factors promote the extension of neurites. In the rat sciatic nerve, we assessed the ability to induce sprouts of the APP isoform that embodies the Kunitz antiprotease domain and other antiproteases. With the electron microscope, axonal sprouts were found when antiproteases were supplied but not after administration of inactive substances. We conclude that axons have a drive to sprout which can be released by the unbalance of an extracellular protease-antiprotease system. We propose that this system is involved in the pathogenesis of Alzheimer's disease.