Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasmodium falciparum merozoite membrane surface antigen 2 (MSA2) has been associated with the development of protective immunity against malaria. MSA2 antibodies were able to inhibit in vitro merozoite invasion. In our search for experimental evidence concerning the participation of MSA2 in merozoite invasion, 40 peptides were synthesized according to sequences reported for the CAMP and FC27 prototype Plasmodium strains. These peptides were purified, 125I-radiolabeled and tested for their ability to bind to erythrocytes. Two MSA2 synthetic peptides with high specific binding to human erythrocytes were found. The peptide coded 4044 (KNESKYSNTFINNAYNMSIR), located in the MSA2 N-terminal conserved region, has an affinity coefficient of 72 nM and showed a positive cooperativity for the receptor-ligand interaction. The other peptide, coded 4053 (NPNHKNAETNPKGKGEVQKP) and located in the central variable region of MSA2, has an affinity coefficient of 49nM and also showed a positive cooperativity for the receptor-ligand interaction. The binding capacity of these peptides is affected by erythrocytes treated with neuraminidase and trypsin, but it is not affected by chymotrypsin. Both of these sequences inhibit in vitro erythrocyte parasite invasion by up to 95% suggesting that they have an important role in the parasite's invasion process. Furthermore, as published previously [A. Saul et al. (1992) J. Immunol., 148, 208-211], a protective B epitope is included in the 4044 peptide sequence.
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PMID:Two MSA 2 peptides that bind to human red blood cells are relevant to Plasmodium falciparum merozoite invasion. 1072 3

The lymphoid surface antigen CD38 is basically a NAD+glycohydrolase, which is also involved in the metabolism of cyclic ADP-ribose. Besides, this ecto-enzyme has potential signalling roles in T- and B-cells. Such multiple functions prompted us to study the molecular dynamics of the CD38 protein and especially the relationship between its ecto-enzymatic active site and its epitope, i.e. the binding site of most known anti-CD38 monoclonal antibodies. Both epitopic and enzymatic sites were shown to be degraded by proteases, such as trypsin or chymotrypsin. This sensitivity was almost entirely suppressed in the presence of substrates or inhibitors. Both sites were also degraded in the presence of reducing agents, as dithiothreitol. Inhibitory ligands induced the same resistance of both sites against reducing attack. The binding of CD38 ligands to the active site triggers therefore conformational changes that shield some backbone bonds and disulfide bridges against, respectively, proteolytic cleavage or reduction. This transconformation was found moreover to irreversibly take place after incubation with substrates such as NAD+ in the presence of dithiothreitol. The epitope remained preserved, while the enzymatic activity was lost. This inactivation probably resulted from the covalent trapping of the catalytically reactive intermediate in the active site (i.e. paracatalytic inactivation). These data have major implications in the knowledge of the CD38 structure, especially with regard to the location of disulfide bridges and their accessibility. Potential consequences of the conformational plasticity of CD38 should also be considered in its physiological functions such as signalling.
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PMID:Probing ligand-induced conformational changes of human CD38. 1080 6

Previously, we identified a defective hepatitis B virus (HBV) which contains a 183 nucleotide deletion in the PreS1 region of the viral genome affecting the S gene promoter in sera from hepatitis B surface antigen (HBsAg)-negative patients with serum HBV-DNA. The aim of this study was to analyse the infectivity of this mutant. Peripheral blood mononuclear cells (PBMC) from a healthy donor were incubated with serum samples from 2 HBsAg-negative patients with serum HBV-DNA (infected with wild-type and deletion mutant HBV), from an HBsAg carrier (infected with wild-type HBV) and from a healthy donor. After 1 week, HBV-DNA was detected by polymerase chain reaction (PCR) in all supernatants and cells incubated with the HBV-DNA-positive inocula. DNase and trypsin pretreatment confirmed intracellular localization of HBV-DNA in cells. HBV-RNA and covalently closed circular HBV-DNA were also detected in PBMC, indicating that the viral DNA infecting these cells was transcriptionally active. Deletion mutant and wild-type HBV were detected in the supernatants and cells infected with the two HBsAg-negative sera, while only wild-type HBV was detected in the supernatant and cells incubated with the serum from the HBsAg-carrier. In conclusion, this HBV deletion mutant can infect, replicate and release viral particles in in vitro infected PBMC.
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PMID:In vitro infection of human peripheral blood mononuclear cells by a defective hepatitis B virus with a deletion in the PreS1 region of the viral genome. 1208 3

Severe acute respiratory syndrome (SARS) coronavirus (SCoV) spike (S) protein is the major surface antigen of the virus and is responsible for receptor binding and the generation of neutralizing antibody. To investigate SCoV S protein, full-length and individual domains of S protein were expressed on the surface of insect cells and were characterized for cleavability and reactivity with serum samples obtained from patients during the convalescent phase of SARS. S protein could be cleaved by exogenous trypsin but not by coexpressed furin, suggesting that the protein is not normally processed during infection. Reactivity was evident by both flow cytometry and Western blot assays, but the pattern of reactivity varied according to assay and sequence of the antigen. The antibody response to SCoV S protein involves antibodies to both linear and conformational epitopes, with linear epitopes associated with the carboxyl domain and conformational epitopes associated with the amino terminal domain. Recombinant SCoV S protein appears to be a suitable antigen for the development of an efficient and sensitive diagnostic test for SARS, but our data suggest that assay format and choice of S antigen are important considerations.
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PMID:Cleavage and serum reactivity of the severe acute respiratory syndrome coronavirus spike protein. 1519 47

Mesenchymal stem/progenitor cells (MSCs) are widely distributed in a variety of tissues in the adult human body (e.g., bone marrow [BM], kidney, lung, and liver). These cells are also present in the fetal environment (e.g., blood, liver, BM, and kidney). However, MSCs are a rare population in these tissues. Here we tried to identify cells with MSC-like potency in human placenta. We isolated adherent cells from trypsin-digested term placentas and established two clones by limiting dilution. We examined these cells for morphology, surface markers, gene expression patterns, and differentiation potential and found that they expressed several stem cell markers, hematopoietic/ endothelial cell-related genes, and organ-specific genes, as determined by reverse transcription-polymerase chain reaction and fluorescence-activated cell sorter analysis. They also showed osteogenic and adipogenic differentiation potentials under appropriate conditions. We suggest that placenta-derived cells have multilineage differentiation potential similar to MSCs in terms of morphology, cell-surface antigen expression, and gene expression patterns. The placenta may prove to be a useful source of MSCs.
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PMID:Human placenta-derived cells have mesenchymal stem/progenitor cell potential. 1534 29

The presence within bone marrow of a population of mesenchymal stem cells (MSCs) able to differentiate into a number of different mesenchymal tissues, including bone and cartilage, was first suggested by Friedenstein nearly 40 years ago. Since then MSCs have been demonstrated in a variety of fetal and adult tissues, including bone marrow, fetal blood and liver, cord blood, amniotic fluid and, in some circumstances, in adult peripheral blood. MSCs from all of these sources can be extensively expanded in vitro and when cultured under specific permissive conditions retain their ability to differentiate into multiple lineages including bone, cartilage, fat, muscle, nerve, glial and stromal cells. There has been great interest in these cells both because of their value as a model for studying the molecular basis of differentiation and because of their therapeutic potential for tissue repair and immune modulation. However, MSCs are a rare population in these tissues. Here we tried to identify cells with MSC-like potency in human placenta. We isolated adherent cells from trypsin-digested term placentas and examined these cells for morphology, surface markers, and differentiation potential and found that they expressed several stem cell markers. They also showed endothelial and neurogenic differentiation potentials under appropriate conditions. We suggest that placenta-derived cells have multilineage differentiation potential similar to MSCs in terms of morphology and cell-surface antigen expression. The placenta may prove to be a useful source of MSCs.
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PMID:Isolation of mesenchymal stem cells from human placenta: comparison with human bone marrow mesenchymal stem cells. 1687 Apr 78

Although IL-3 is commonly used for culture of human progenitor-derived mast cells together with Stem cell factor (SCF) and IL-6, the effect of IL-3 on human mast cell differentiation has not been well elucidated. Human bone marrow CD34+ progenitors were cultured for up to 12 weeks in the presence of rhSCF and rhIL-6 either with rhIL-3 (IL-3 (+)) or without rhIL-3 (IL-3 (-)) for the initial 1-week of culture. Total cell number increased at 2 weeks in IL-3 (+), as compared to IL-3 (-), but changes in the appearance of mast cells were delayed. When IL-3 was present for the initial 1-week culture, granules looked more mature with IL-3 than without IL-3. However, tryptase and chymase contents, and surface antigen expression (CD18, CD51, CD54, and CD117) were not altered by IL-3. Surface expression and mRNA level of FcepsilonRIalpha and histamine release by crosslinking of FcepsilonRIalpha did not differ from one preparation to the next. GeneChip analysis revealed that no significant differences were observed between IL-3 (+) and IL-3 (-) cells either when inactivated or activated by aggregation of FcepsilonRIalpha. These findings indicate that initial incubation of human bone marrow CD34+ progenitors with IL-3 does not affect the differentiation of mast cells.
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PMID:Interleukin-3 does not affect the differentiation of mast cells derived from human bone marrow progenitors. 1821 96

Seroconversion from hepatitis B surface antigen (HBsAg) to antibodies against HBsAg (anti-HBs) usually indicates resolution of hepatitis B virus (HBV) infection. Here, two HBV-infected patients with seroconversion to anti-HBs were found to be persistently positive for HBeAg and HBV DNA. Immunohistology of liver biopsies confirmed the expression of HBV proteins in the liver of one patient. The neutralizing ability of anti-HBs in patient sera was demonstrated by blocking HBV infection of primary tupaia hepatocytes. Analysis of the HBsAg-encoding region of HBV isolates from patients indicated the coexistence of heterogeneous HBV genomes in patients. The majority of recombinant variant HBsAg was reactive in HBsAg assays and was able to bind to anti-HBs. Circulating immune complexes (CIC) of HBsAg in patient sera could be detected by polyethylene glycol precipitation and trypsin digestion. Thus, neutralizing anti-HBs may appear in chronic HBV carriers for long periods but does not necessarily lead to complete viral clearance.
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PMID:Elimination of hepatitis B virus surface antigen and appearance of neutralizing antibodies in chronically infected patients without viral clearance. 2081 50

Eleven murine monoclonal antibodies (MABs) were produced using human mammary cancer (HMC) cell lines as immunogens: None reacted with normal breast tissue, but each had a distinctive pattern of reactivity with HMC and benign proliferative lesions. Two MABs bound to overlapping epitopes of an M(r) 47,000 cell-surface antigen and were endocytosed: nine bound to secretable intracytoplasmic antigens(s). Four of the MABs immunoprecipitate antigens that upon reduction yielded an M(r) 73,000 moiety. None reacted with components of milk. All antigens were sensitive to trypsin, three to periodate oxidation but none to neuraminidase. One cell-surface-localizing MAB investigated, selectively localized in HMC xenografts.
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PMID:Monoclonal-antibodies to human breast-cancer associated antigens. 2155 26

The aim of the study was to assess the expression of transcriptional factor genes and embryonic stem cell-like characters in the placental membrane of buffalo (Bubalus bubalis). Along with the placenta, amniotic fluid, maternal peripheral blood, and umbilical cord blood samples were taken for the future study. The isolation and culture of cells from the placental membrane was followed by the determination of RT-PCR-based markers (Oct-4, Nanog, Sox-2, alkaline phosphatase, stem cell factor, and Nestin) of these cells. Placental membrane cells also positively expressed alkaline phosphatase staining. We isolated adherent cells from trypsin-EDTA-digested placentas and examined these cells for morphology, surface markers, and differentiation potential and found that they expressed several stem cell markers. They also showed neurogenic and adipogenic differentiation potentials under appropriate guided conditions. We suggest that placenta-derived cells have multilineage differentiation potential similar to mesenchymal stem cells in terms of morphology and cell-surface antigen expression. The placenta may prove to be a useful source of mesenchymal stem cells.
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PMID:Expression of transcriptional factor genes (Oct-4, Nanog, and Sox-2) and embryonic stem cell-like characters in placental membrane of Buffalo (Bubalus bubalis). 2252 3


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