Human leukocyte elastase is an important selection target of inflammation and cancer. In this paper, a high throughput screening model was established for screening human leukocyte elastase inhibitors from thousands of strains of actinomycetes. As a result, a strain, N01WA-735 with potent suppression activity was isolated. Firstly, the strain N01WA-735 was identified as Streptomyces according to morphology and biochemical analysis. The Streptomyces N01WA-735 was processed by solvent extraction, silica column chromatography, Sephadex LH-20 column chromatography and crystallization to get a pure active compound named N01WA-735E. Its chemical structure was elucidated as the same as that of the compound named BE-52440A by physicochemical properties and spectral data of UV, MS, 1H-NMR and 13C-NMR respectively. The compound showed a strong inhibitory activity against human leukocyte elastase with IC50 of 3.02 micromol/L. The compound is reported as a human leukocyte elastase inhibitor for the first time.
Humans ; Leukocyte Elastase ; antagonists & inhibitors ; Protease Inhibitors ; isolation & purification ; metabolism ; Streptomyces ; isolation & purification ; metabolism

Eleven compounds were isolated from the culture of Streptomyces sp. CPCC 202950 by a combination of various chromatographic techniques including column chromatography over macroporous resin HP-20, MCI, and reversed-phase HPLC. Their structures were identified as 1H-pyrrole-2-carboxamide(1),5'-deoxy-5'-methylthioinosine(2), vanillamide(3), trans-3-methylthioacrylamide(4), 1,2,3,4-Tetraydro-1H-pyrido[3,4-b]indole-3-carboxylic acid(5), cyclo(L-pro-L-tyr) (6), N-[2-(4-hydroxyphenyl)]ethylacetamide(7), benzamide (8), cyclo ('L-leucyl-trans-4-hydroxy-L-proline)(9), cyclo-(Phe-Gly) (10), and tryptophan (11). Among them, compounds 1 and 2 were new natural products. In the preliminary assays, none of the compounds exhibited obvious inhibition of HIV-1 protease activity (IC50 > 10 micromol x L(-1)).
Culture Media ; chemistry ; metabolism ; HIV Protease ; analysis ; HIV Protease Inhibitors ; chemistry ; isolation & purification ; Molecular Structure ; Spectrometry, Mass, Electrospray Ionization ; Streptomyces ; chemistry ; metabolism

The effect of a secretory proteinase from the pathogenic amoebae Acanthamoeba castellanii on hosts defense-oriented or regulatory proteins such as immunoglobulins, interleukin-1, and protease inhibitors was investigated. The enzyme was found to degrade secretory immunoglobulin A (sIgA), IgG, and IgM. It also degraded interleukin-1alpha (IL-1alpha) and IL-1beta. Its activity was not inhibited by endogenous protease inhibitors, such as alpha2-macroglobulin, alpha1-trypsin inhibitor, and alpha2-antiplasmin. Furthermore, the enzyme rapidly degraded those endogenous protease inhibitors as well. The degradation of hosts defense-oriented or regulatory proteins by the Acanthamoeba proteinase suggested that the enzyme might be an important virulence factor in the pathogenesis of Acanthamoeba infection.
Acanthamoeba/*enzymology/pathogenicity ; Animals ; Endopeptidases/*physiology ; Immunoglobulins/*metabolism ; Interleukin-1/*metabolism ; Protease Inhibitors/*metabolism ; Support, Non-U.S. Gov't ; Virulence

The aim of this study was to prepare tandem multimeric proteins of BmSPI38, a silkworm protease inhibitor, with better structural homogeneity, higher activity and stronger antifungal ability by protein engineering. The tandem multimeric proteins of BmSPI38 were prepared by prokaryotic expression technology. The effects of tandem multimerization on the structural homogeneity, inhibitory activity and antifungal ability of BmSPI38 were explored by in-gel activity staining of protease inhibitor, protease inhibition assays and fungal growth inhibition experiments. Activity staining showed that the tandem expression based on the peptide flexible linker greatly improved the structural homogeneity of BmSPI38 protein. Protease inhibition experiments showed that the tandem trimerization and tetramerization based on the linker improved the inhibitory ability of BmSPI38 to microbial proteases. Conidial germination assays showed that His₆-SPI38L-tetramer had stronger inhibition on conidial germination of Beauveria bassiana than that of His₆-SPI38-monomer. Fungal growth inhibition assay showed that the inhibitory ability of BmSPI38 against Saccharomyces cerevisiae and Candida albicans could be enhanced by tandem multimerization. The present study successfully achieved the heterologous active expression of the silkworm protease inhibitor BmSPI38 in Escherichia coli, and confirmed that the structural homogeneity and antifungal ability of BmSPI38 could be enhanced by tandem multimerization. This study provides important theoretical basis and new strategies for cultivating antifungal transgenic silkworm. Moreover, it may promote the exogenous production of BmSPI38 and its application in the medical field.
Animals ; Antifungal Agents/pharmacology* ; Escherichia coli/metabolism* ; Proteins/metabolism* ; Protease Inhibitors/chemistry* ; Bombyx/chemistry* ; Saccharomyces cerevisiae/metabolism* ; Peptide Hydrolases

Japanese encephalitis virus (JEV) is a single-stranded and positive-sense RNA, which has a single ORF (open reading frame), encoding a polyprotein precursor. Non-structural protein 3 (NS3) plays an important role in processing the polyprotein precursor and has become an important drug target of flavivirus. In this study, NS2BH-NS3 gene was amplified by PCR and subcloned to the prokaryotic expression plasmid, resulting pET30a-NS2BH-NS3. The fusion protein was expressed in Escherichia coli BL21 (DE3) in soluble form after induction by Isopropyl beta-D-1-Thiogalactopyranoside (IPTG). The recombinant protein was purified by Ni-NTA affinity column. Then a fluorescence resonance energy transfer (FRET) method was used to determine enzymatic activity and the assay conditions were optimized. After screening 113 compounds, we found two compounds inhibiting the activity of NS2BH-NS3. This study provides a convenient and cost-effective method for screening of JEV NS3 protease inhibitor.
Encephalitis Virus, Japanese ; enzymology ; Escherichia coli ; metabolism ; High-Throughput Screening Assays ; Protease Inhibitors ; chemistry ; RNA Helicases ; metabolism ; Recombinant Fusion Proteins ; metabolism ; Serine Endopeptidases ; metabolism ; Viral Nonstructural Proteins ; metabolism

OBJECTIVETo investigate the effects of various HIV protease inhibitors on the function of pancreatic beta-cells.

METHODSRat insulinoma INS-1 cells were incubated with different concentrations of ritonavir or amprenavir for 48 h and stimulated with 20 mmol/L D-glucose for 30 min. The rate of insulin release was measured in the supernatant by ELISA, normalized to cellular DNA contents. Cells were counted with trypan blue and MTT test were determined to evaluate the effect of protease inhibitors on cell viability.

RESULTRitonavir treatment significantly decreased baseline insulin release and glucose-stimulated insulin release in a dose-dependent manner (r=-0.861, -0.839, both P<0.01). For 10 micromol/L of ritonavir, the decrease rate of baseline insulin secretion and glucose-stimulated insulin secretion was 46% and 47%, respectively. Amprenavir had no effect on the rate of insulin release.

CONCLUSIONVarious HIV protease inhibitors present different effect on the insulin release of pancreatic beta-cells.

Animals ; Carbamates ; pharmacology ; HIV Protease Inhibitors ; pharmacology ; Insulin ; secretion ; Insulinoma ; metabolism ; pathology ; Islets of Langerhans ; metabolism ; Pancreatic Neoplasms ; metabolism ; pathology ; Rats ; Ritonavir ; pharmacology ; Sulfonamides ; pharmacology

Calpain I (mu-calpain) and II (m-calpain) are well known calcium-activated neutral cysteine proteases. Many reports have shown that activation of calpain is related to cataract formation, neuronal degeneration, blood clotting, ischemic injuries, muscular dystrophy and cornified cell envelope (CE) formation. Here, we report that insoluble CE formation was reduced after treatment with calpain I inhibitor (N-acetyl-leucyl-leucyl-norleucinal) on normal human epidermal keratinocytes (NHEK), whereas serine and thiol protease inhibitors had no effect on the reduction of CE. When NHEK cells were confluent, keratinocytes were treated with various concentrations (0.5 microM-0.5 mM) of calpain I inhibitor or serine and thiol protease inhibitors under calcium induced differentiation. Insoluble CE formation was reduced about 90% in the 50 microM calpain inhibitor I treated group by day 9 of culture, whereas insoluble CE was reduced only 10% in the same condition. Interestingly TGase activity was blocked by 90% in the 0.5 mM calpain inhibitor treated group within 72 h, whereas TGase activity was retained by 80% in the 0.5 mM serine protease inhibitor treated group at 7 day treatment. Therefore it can be suggested that cysteine protease calpains might be responsible for the activation of the TGase 1 enzyme to complete insoluble CE formation during epidermal differentiation.
Calcium/pharmacology ; Calpain/metabolism* ; Calpain/antagonists & inhibitors* ; Cell Differentiation ; Dose-Response Relationship, Drug ; Epidermis/metabolism ; Human ; In Vitro ; Keratinocytes/metabolism ; Keratinocytes/enzymology ; Protease Inhibitors/pharmacology ; Protein-Glutamine gamma-Glutamyltransferase/metabolism* ; Protein-Glutamine gamma-Glutamyltransferase/antagonists & inhibitors* ; Tissue Culture

This study was aimed to investigate the effects of proteasome inhibitor bortezomib (Velcade, PS-341) on the activation of NF-kappaB and the expression of intercellular adhesion molecule-1 (ICAM-1) in K562 cells. The K562 cells were incubated in the culture of RPMI 1640 with 10% calf serum in 12-well plates and exposed to 0, 10, 20, 30, 50 and 100 nmol/L of bortezomib for 6 hours. The activation of NF-kappaB was analyzed by SP immunohistochemistry, meanwhile RT-PCR was performed to detect expression of ICAM-1. The results showed that the activation of NF-kappaB and the expression of ICAM-1 in K562 cells decreased significantly after bortezomib treatment. The inhibitory effect on ICAM-1 was probably related with the activity suppression of NF-kappaB. It is concluded that proteasome inhibitor bortezomib downregulates the expression of K562 cell ICAM-1 by inhibiting the activity of NF-kappaB, which provides a new way for the target therapy in acute leukemia.
Boronic Acids ; pharmacology ; Bortezomib ; Humans ; Intercellular Adhesion Molecule-1 ; metabolism ; K562 Cells ; NF-kappa B ; metabolism ; Protease Inhibitors ; pharmacology ; Pyrazines ; pharmacology

The activation of hepatic stellate cells (HSCs) and their transformation to myofibroblasts are the key steps in the pathological progress of liver fibrosis. The transforming growth factor-β (TGFβ)/Smad pathway is involved in the proliferation and collagen synthesis of HSCs. This study aimed to examine the effect of the protease inhibitor MG132 on the signaling pathway of TGFβ/Smad in HSC-T6 cells and seek a novel therapeutic approach for liver fibrosis. The HSC-T6 cells were treated with MG132 at different concentrations (0-10 μmol/L). Cell proliferation was detected by MTT method. The mRNA and protein expression levels of TGFβ1, Smad3 and Smad7 were determined in HSC-T6 cells by real-time PCR and Western blotting, respectively, after treatment with MG132 at different concentrations (1, 2, 3 μmol/L) or RPMI1640 alone (serving as control). The results showed that MG132 could inhibit the proliferation of HSC-T6 cells in a dose-dependent manner, and the IC(50) of MG132 was 6.84 μmol/L. After treatment with MG132 at 1, 2 or 3 μmol/L for 24 h, the mRNA expression levels of TGF-β1 and Smad3 were significantly decreased (P<0.05), but the Smad7 mRNA expression had no significant change (P>0.05). There was also a significant decrease in the protein expression level of TGF-β1 and Smad3 (P<0.05). However, the expression of Smad7 protein was substantially increased when compared with the control group (P<0.05). It was concluded that the inhibition of TGFβ/Smad pathway in HSC-T6 cells by MG132 can reduce the production of profibrosis factors (TGFβ1, Smad3) and promote the expression of anti-fibrosis factor (Smad7), suggesting that MG132 may become a potential therapeutic alternative for liver fibrosis.
Animals ; Cell Line ; Leupeptins ; pharmacology ; Protease Inhibitors ; pharmacology ; Rats ; Signal Transduction ; drug effects ; Smad Proteins ; metabolism ; Transforming Growth Factor beta ; metabolism

OBJECTIVETo observe the effect of gut protease activity on visceral hypersensitivity in rats with acute restraint stress.

METHODSSprague-Dawley rats were given 30, 100 or 300 mg/kg camostat mesilate (CM), a protease inhibitor, or saline intragastrically 30 min before acute restraint stress induced by wrapping the fore shoulders, upper forelimbs and thoracic trunk for 2 h. Visceral perception of the rats was quantified as the visceral motor response with an electromyography, and the rectal mucosa and feces protease activity and spinal c-fos expression were measured.

RESULTSCM dose-dependently reduced visceral sensitization elicited by rectal distension, but these doses did not completely inhibit stress-induced visceral sensitization. In normal rats, c-fos expression was found mainly in the superal spinal cord dorsal horn, and after the administration the CM, c-fos-positive cells decreased significantly in all dose groups (P<0.05). In 30 mg/kg CM group, fecal and rectal mucosal protease activity significantly decreased as compared with that in the stress group (P<0.05), and as CM dose increased to 100 and 300 mg/kg, the protease activity decreased even further (P<0.01).

CONCLUSIONThe gut protease is involved in acute stress-induced visceral hypersensitivity, and CM can lower the visceral sensitivity and spinal c-fos expression in rats.

Animals ; Gabexate ; analogs & derivatives ; pharmacology ; Protease Inhibitors ; pharmacology ; Proto-Oncogene Proteins c-fos ; metabolism ; Rats ; Rats, Sprague-Dawley ; Restraint, Physical ; Spinal Cord ; metabolism ; Stress, Physiological