Glutinous rice wine is a traditional food in south of China and it can coagulate milk. It has been proved that its function of coagulating milk is because of the presence of milk-clotting enzyme produced by microorganisms in glutinous rice wine. The aim of this work is to isolate milk-clotting enzyme producing strain from glutinous rice wine and study the fermentation condition. We screened out four bacteria and fungus by gradient dilution. It was proved that mold played the most important role in the production of milk-clotting enzyme. This is further confirmed by casein plate method. The optimization of fermentation conditions revealed that two times concentrated potato medium supplemented with 5% glucose without additional nitrogen was better for production of the enzyme. The enzyme activity was increased 144% under the conditions established.
Aspartic Acid Endopeptidases ; biosynthesis ; Bacteria ; isolation & purification ; metabolism ; Culture Media ; Fermentation ; Oryza ; metabolism ; Wine ; microbiology ; Yeasts ; cytology ; isolation & purification ; metabolism

Leader peptidase is a novel serine protease in Escherichia coli, which catalyzes the cleavage of amino-terminal signal sequences from exported proteins. It is an integral membrane protein containing two transmembrane segments with its carboxy-terminal catalytic domain residing in the periplasmic space. Recently, the x-ray crystal structure of signal peptidase-inhibitor complex showed that Asp 280, a highly conserved consensus sequence of E. coli leader peptidase is the closest charged residue in the vicinity of two catalytic dyad, Ser 90 and Lys 145, and it is likely held in place by a salt bridge to Arg 282. Possible roles of Asp 280 and Arg 282 in the structure-catalytic function relationship were investigated by the site-directed mutagenesis of Asp 280 substituted with alanine, glutamic acid, glycine, or asparagine and of Arg 282 with methionine. All of mutants purified with nickel affinity chromatography were inactive using in vitro assay. It is surprising to find complete lose of activity by an extension of one carbon units in the mutant where Asp 280 is substituted with glutamic acid. These results suggest that Asp 280 and Arg 282 are in a sequence which constitutes catalytic crevice of leader peptidase and are essential for maintaining the conformation of catalytic pocket.
Aspartic Acid/chemistry* ; Bacterial Outer Membrane Proteins/metabolism ; Blotting, Western ; Escherichia coli/enzymology* ; Escherichia coli/chemistry ; Micrococcal Nuclease/metabolism ; Mutagenesis, Site-Directed ; Oligonucleotides ; Protein Precursors/metabolism ; Serine Endopeptidases/metabolism* ; Serine Endopeptidases/genetics ; Serine Endopeptidases/chemistry* ; Structure-Activity Relationship

OBJECTIVETo explore the effect of Panax notoginseng saponin (PNS) on the activity and content of beta-secretase in the brain of senescence accelerated mouse-prone 8 (SAMP8) mice with Alzheimer's disease.

METHODSTotally 32 SAMP8 mice were randomly divided into the normal control group, the high dose PNS group (200 mg/kg), the low dose group (100 mg/kg), and the huperzine A group (0.3 mg/kg), 8 in each group. Equal volume of double distilled water was given to those in the normal control group. All medication was given by gastrogavage, once daily for two successive months. The activity of BACE1 was assayed by direct immunofluorescent method (DIF). The content of BACE1 protein was detected by Western blot.

RESULTSThe relative fluorescence units (RFU/microg) was 2.008 +/- 0.031 in the high dose PNS group, 2.221 +/- 0.029 in the low dose PNS group, and 2.267 +/- 0.076 in the huperzine A group, all lower than that in the normal control group (2.403 +/- 0.058; all P < 0.01). The content of BACE1 protein was 0.900 +/- 0.028 in the high dose PNS group, 1.000 +/- 0.032 in the low dose PNS group, and 0.837 +/- 0.080 in the huperzine A group, all lower than that in the normal control group (2.210 +/- 0.074, all P < 0.01).

CONCLUSIONPNS higher than 100 mg/kg could decrease the activity of BACE1 and down-regulate the content of BACE1 protein in the brain of SAMP8 mice.

Aging ; Alzheimer Disease ; metabolism ; Amyloid Precursor Protein Secretases ; metabolism ; Animals ; Aspartic Acid Endopeptidases ; metabolism ; Brain ; metabolism ; Disease Models, Animal ; Male ; Mice ; Panax notoginseng ; RNA, Messenger ; genetics ; Saponins ; pharmacology

To generate active recombinant human beta-secreatase (BACE1) for studying its interaction with its inhibitors, we constructed two recombinant plasmids, pPIC9K-MetBACE22 (bearing pro-bace1 gene) and pPIC9K-MetBACE46 (bearing bace1 gene). These two plasmids were then transformed into Pichia pastoris GS115 by electroporation to obtain the recombinant strains 9k-B22 and 9k-B46. After induction in buffered methanol complex medium, we found the supernatant activity of 9k-B22 significantly higher than that of 9k-B46. The culture filtrate of 9k-B22 was concentrated, and then purified by HisTrap affinity column. The purified proteins, showing good BACE1 protease activity, were found to be a mixture of glycoproteins because they can be stained by periodic acid-Schiff reagent. After this mixture was treated with Endo H(f) (a recombinant protein of endoglycosidase H), we found two new adjacent bands around 50 kDa on SDS-PAGE. These two bands were cut and subjected to peptide mass fingerprint analysis, and identified as proBACE1 and BACE1 proteins. Enzyme assays revealed that the activities of both BACE1 proteins in glycosylated and deglycosylated form were lower than that of commercial BACE1 (expressed in HEK-293), inferring glycosylation and the type of glycosylation are crucial to the activity. However, we found no apparent difference in the inhibition of those all above three enzyme forms by one known BACE1 inhibitor. This observation demonstrated that the glycosylation of BACE1 by Pichia pastoris does not affect its interaction with this inhibitor. After optimization of culture conditions, the production of BACE1 in Pichia pastoris was enhanced to about 1 mg/L. This work enables us to further investigate the interaction of BACE1 and its inhibitors, and assists in discovering and optimizing BACE1 inhibitors as anti-Alzheimer's disease agents.
Amyloid Precursor Protein Secretases ; biosynthesis ; genetics ; Aspartic Acid Endopeptidases ; biosynthesis ; genetics ; Electroporation ; Humans ; Pichia ; genetics ; metabolism ; Plasmids ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification

OBJECTIVETo investigate the value of detecting thyroid transcription factor 1 (TTF-1) and Noval aspartic proteinase of pepsin family A (napsin A) in pleural fluid cell blocks in cytopathologic diagnosis of pulmonary adenocarcinoma.

METHODSConventional cell smears of pleural effusions were obtained from 48 patients with a history of lung adenocarcinoma for cytological analysis. The cell blocks were prepared using the cytological specimens and examined with immunohistochemistry for TTF-1 and napsin A. The rates of a positive diagnosis of pulmonary adenocarcinoma were compared between the two methods, and the diagnositic value of TTF-1 and napsin A in pleural fluid cell blocks was evaluated.

RESULTSImmuno- histochemistry of the cell block sections yielded a significantly higher positive rate of diagnosis than cytological analysis of conventional cell smear (84.44% vs 55.56%, P<0.05). Most of the pleural fluid cell blocks showed positive expressions of TTF-1 (36/38, 94.74%) and napsin A (30/38, 78.95%), and none of samples showed TTF-1 or napsin A expression in the mesothelial cells (P<0.05). The combination detection of TTF-1 and napsin A in pleural fluid cell blocks had a high diagnosis value with a diagnostic sensitivity of 97.37% and a specificity of 100% for pulmonary adenocarcinoma.

CONCLUSIONSThe combined detection of TTF-1 and napsin A in pleural fluid cell blocks facilitates cytopathologic diagnosis of pulmonary adenocarcinoma.

Adenocarcinoma ; diagnosis ; metabolism ; Aspartic Acid Endopeptidases ; metabolism ; Biomarkers, Tumor ; metabolism ; Humans ; Immunohistochemistry ; Lung Neoplasms ; diagnosis ; metabolism ; Nuclear Proteins ; metabolism ; Pleural Effusion ; Sensitivity and Specificity ; Thyroid Nuclear Factor 1 ; Transcription Factors ; metabolism

OBJECTIVETo investigate the effects of exogenous hydrogen sulfide (H2S) on β-site APP cleaving enzyme 1 (BACE-1) and β-amyloid peptide (Aβ) metabolism in primary culture of neurons under high-glucose condition.

METHODSThe cortical neurons in primary culture under normal and high glucose (60 mmol/L) conditions for 24 h were exposed to 25, 50 and 100 µmol/L NaHS. Aβ1-42 concentration in the cell culture was measured by ELISA, and BACE-1 mRNA and protein levels were detected by fluorescent quantitative real-time PCR and Western blotting, respectively.

RESULTSCompared with the neurons cultured in normal glucose, the neurons exposed to high glucose showed significantly increased Aβ1-42 concentration and BACE-1 mRNA and protein expressions (P<0.05). Exposure to 25, 50 and 100 µmol/L NaHS significantly decreased Aβ1-42 concentration and BACE-1 mRNA and protein expressions in the high-glucose cell culture (P<0.05).

CONCLUSIONNeurons exposed to high glucose exhibit increased Aβ1-42 levels and BACE-1 mRNA and protein expressions, which can be concentration-dependently decreased by NaHS.

Amyloid Precursor Protein Secretases ; metabolism ; Amyloid beta-Peptides ; metabolism ; Animals ; Aspartic Acid Endopeptidases ; metabolism ; Cells, Cultured ; Culture Media ; chemistry ; Glucose ; chemistry ; Hydrogen Sulfide ; pharmacology ; Neurons ; drug effects ; metabolism ; Peptide Fragments ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the clinicopathologic characteristics of primary salivary gland-type lung carcinomas, and the immunophenotypic value of TTF-1, Napsin A and Ki-67 in their differential diagnosis.

METHODSTotally 48 special type lung cancer surgical removal specimens were collected in China-Japan Friendship Hospital during September 2009 to December 2014. A panel of immunohistochemical markers (TTF-1, Napsin A, Ki-67, CK5/6, CK7 and p63) were conducted on these specimens.

RESULTSThe 48 cases of special type lung cancer included 25 cases of primary salivary gland-type lung carcinoma (18 cases of adenoid cystic carcinoma and 7 cases of mucoepidermoid carcinoma), 5 cases pulmonary adenocarcinoma with mucoepidermoid carcinoma-like or adenoid cystic carcinoma-like structure, and 18 cases of pulmonary adenosquamous carcinoma. Compared with pulmonary adenocarcinoma with mucoepidermoid carcinoma-like or adenoid cystic carcinoma-like structure and pulmonary adenosquamous carcinoma, primary salivary gland-type lung carcinomas have special characteristics in median age, sex, location, tumor size, LN involvement and pleura invasion, with negative TTF-1 and Napsin A expression as well as lower Ki-67 index detected by immunohistochemistry. Primary salivary gland-type lung carcinomas usually have an indolent behavior.

CONCLUSIONSPrimary salivary gland-type lung carcinomas are low-aggressive entities. The origins of primary salivary gland-type lung carcinomas were different from that of pulmonary adenocarcinoma with mucoepidermoid carcinoma-like or adenoid cystic carcinoma-like structure and pulmonary adenosquamous carcinoma. Negative TTF-1 and Napsin A expression as well as Ki-67 index lower than 20% have special value for primary salivary gland-type lung carcinomas in their differential diagnosis.

Adenocarcinoma ; diagnosis ; Aspartic Acid Endopeptidases ; metabolism ; Biomarkers, Tumor ; metabolism ; Carcinoma, Adenoid Cystic ; diagnosis ; Carcinoma, Mucoepidermoid ; diagnosis ; China ; DNA-Binding Proteins ; metabolism ; Humans ; Immunohistochemistry ; Ki-67 Antigen ; metabolism ; Lung Neoplasms ; diagnosis ; Transcription Factors

BACKGROUNDEpithelial-mesenchymal transition is a cellular process characterized by the loss of cell adhesion, inhibition of E-cadherin expression, and increased cell mobility. Cells without Napsin A are susceptible to transition. Further studies are required to investigate whether this transition can be reversed by restoration of Napsin A.

METHODSA Napsin A expression vector PLJM1-Napsin A plasmid was constructed and then transfected into the epithelial cell line A549 by lentivirus transfection to obtain A549-PLJM1-Napsin A cell line. Cell proliferation was assayed by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide and cell cycle was measured by flow cytometry. The E-cadherin, type I collagen, and focal adhesion kinase mRNA level was detected by reverse transcription-polymerase chain reaction. The Napsin A, E-cadherin, type I collagen, and focal adhesion kinase protein level in A549 cells was detected by Western blotting.

RESULTSTransforming growth factor-b1 induced epithelial-mesenchymal transition in A549 cells, as demonstrated by significant reduction of E-cadherin mRNA and protein levels (P < 0.01) as well as up-regulation of type I collagen (P < 0.01). Transfection of Napsin A in A549 cells can partially block the transforming growth factor-b1-regulated expression of E-cadherin and type I collagen (P < 0.01). In addition, transforming growth factor-b1-induced cell proliferation was inhibited by Napsin A (P < 0.01). Further study demonstrated that Napsin A caused G(0)/G(1) arrest and inhibited the expression of focal adhesion kinase (P < 0.01), a key protein in the integrin signaling pathway, in the in vitro epithelial-mesenchymal transition model.

CONCLUSIONSSustained Napsin A expression in A549 cells can inhibit the transforming growth factor-b1-induced epithelial-mesenchymal transition. This may be due to the Napsin A-mediated inhibition of focal adhesion kinase expression and integrin signaling pathway.

Aspartic Acid Endopeptidases ; genetics ; metabolism ; Cadherins ; genetics ; metabolism ; Cell Line ; Collagen Type I ; genetics ; metabolism ; Epithelial-Mesenchymal Transition ; drug effects ; genetics ; Focal Adhesion Protein-Tyrosine Kinases ; genetics ; metabolism ; Humans ; Transfection ; Transforming Growth Factor beta1 ; pharmacology

Physalin B (PB), one of the major active steroidal constituents of Solanaceae Physalis plants, has a wide variety of biological activities. We found that PB significantly down-regulated β-amyloid (Aβ) secretion in N2a/APPsw cells. However, the underlying mechanisms are not well understood. In the current study, we investigated the changes in key enzymes involved in β-amyloid precursor protein (APP) metabolism and other APP metabolites by treating N2a/APPsw cells with PB at different concentrations. The results indicated that PB reduced Aβ secretion, which was caused by down-regulation of β-secretase (BACE1) expression, as indicated at both the protein and mRNA levels. Further research revealed that PB regulated BACE1 expression by inducing the activation of forkhead box O1 (FoxO1) and inhibiting the phosphorylation of signal transducer and activator of transcription 3 (STAT3). In addition, the effect of PB on BACE1 expression and Aβ secretion was reversed by treatment with FoxO1 siRNA and STAT3 antagonist S3I-201. In conclusion, these data demonstrated that PB can effectively down-regulate the expression of BACE1 to reduce Aβsecretion by activating the expression of FoxO1 and inhibiting the phosphorylation of STAT3.
Alzheimer Disease ; Amyloid Precursor Protein Secretases/metabolism* ; Amyloid beta-Peptides/metabolism* ; Aspartic Acid Endopeptidases/metabolism* ; Down-Regulation ; Forkhead Box Protein O1/genetics* ; Humans ; Phosphorylation ; STAT3 Transcription Factor/metabolism* ; Secosteroids

OBJECTIVETo investigate the expression of tumor stem cell marker CD133 and endothelin-converting enzymes (ECE) in non-small cell lung carcinoma (NSCLC) and their association with NSCLC lymphoid metastasis.

METHODSCD133 and ECE expressions was detected immunohistochemically in the specimens from 77 patients with NSCLC, and the association of CD133 and ECE expressions with the tumor size, histological type, differentiation, lymphoid metastasis, and prognosis of NSCLC was analyzed.

RESULTSThe positive expression rate of CD133 and ECE was 51.9% (40/77) and 45.5% (35/77) in these specimens, respectively. Both CD133 and ECE expressions were associated positively with lymphoid metastasis (r=0.246 and 0.339, P<0.05), and inversely with the survival time of the patients (P<0.05). CD133 and ECE expressions were not related to tumor size, histological type, and differentiation of the tumor (P>0.05). CD133 expression was associated positively with ECE expression in NSCLC (r=0.249, P<0.05).

CONCLUSIONCD133 and ECE expressions are associated with lymphoid metastasis and prognosis of NSCLC, and their overexpression often suggests unfavorable prognosis of NSCLC.

AC133 Antigen ; Adult ; Aged ; Antigens, CD ; biosynthesis ; Aspartic Acid Endopeptidases ; biosynthesis ; Carcinoma, Non-Small-Cell Lung ; metabolism ; pathology ; Endothelin-Converting Enzymes ; Female ; Glycoproteins ; biosynthesis ; Humans ; Immunohistochemistry ; Lung Neoplasms ; metabolism ; pathology ; Lymphatic Metastasis ; Male ; Metalloendopeptidases ; biosynthesis ; Middle Aged ; Peptides ; Prognosis