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)

A comparison was made of the activity of synovial fluid (SF) lymphocytes with peripheral blood lymphocytes in antibody-mediated and mitogen-induced lymphocyte cytotoxicity in patients with a variety of inflammatory joint diseases. SF lymphocytes consistently showed little or no antibody-mediated cytotoxicity (AMC) although mitogen-induced cytotoxic activity was comparable with that of the peripheral blood lymphocytes. Blocking substances on the cell surface were not responsible for the lack of AMC by SF lymphocytes as preincubation at 37 degrees C and enzyme treatment (trypsin, neuraminidase) of the cells did not restore activity. The lack of AMC by SF cells from a variety of inflammatory joint fluids demonstrates that this may be a consequence of inflammation in the joint and excludes the possibility that this is a specific property of fluids from certain conditions such as rheumatoid arthritis. Lymphocytes thought to be involved in AMC have a characteristic surface morphology (Fc receptor positive, E rosette negative, surface immunoglobulin negative). Such lymphocytes are present in synovial fluid in comparable proportions to those in blood. Hence the absence of AMC indicates that functional assays must be used in determining the presence or absence of cells with special functions.
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PMID:Lymphocyte studies in rheumatoid arthritis. II. Antibody-mediated and mitogen-induced lymphocyte cytotoxicity in synovial fluid and peripheral blood. 71 73

Complexes of labelled proteinases (subtilopeptidase A, trypsin) with serum alpha 1-macroglobulin or alpha 2-macroglobulin are rapidly taken up in vitro by rabbit alveolar macrophages and peritoneal macrophages but not by mixed rabbit peripheral blood leukocytes. Enzyme, not bound to alpha 1- or alpha 2-macroglobulin, does not become associated with alveolar macrophages. Chemically inactivated subtilopeptidase A does not bind to alpha 1- or alpha 2-macroglobulin; chemically inactivated subtilopeptidase A in mixtures with alpha 1 - or alpha 2-microglobulin, does not interact with alveolar macrophages. Blocking experiments confirmed that the interaction of proteinase with alveolar macrophages is complex specific; uptake of labelled complex was prevented by the simultaneous addition of macroglobulin complexes formed with non-labelled subtilopeptidase A, subtilopeptidase B, trypsin or chymotrypsin but not by macroglobulin alone. The findings demonstrate a complex-specific interaction between proteinase-alpha-macroglobulin complexes and macrophages.
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PMID:Uptake of proteinase-alpha-macroglobulin complexes by macrophages. 120 Dec 82

Human epidermal keratinocytes constitutively produce a variety of cytokines, including neutrophil chemotactic peptide named epidermal cell-derived thymocyte-activating factor, which has been later confirmed to be interleukin 1 (IL-1). Because recombinant IL-1 lacks chemotactic activity, in the present study, we examined the exact nature of the neutrophil chemotactic peptide in the culture supernatant of normal human epidermal keratinocytes. Normal human epidermal keratinocytes produced a neutrophil chemotactic factor, which was also chemotactic for T lymphocytes. Molecular sieve chromatography revealed an approximate molecular size of 11,000 daltons. The activity was retained after heating at 100 degrees C for 10 min, and at a pH between 4 and 11, but was partially inactivated at pH 3, or by trypsin treatment. The chemotactic activity was not inhibited by the treatment with anti-IL-1 antibody. Its production by keratinocytes was stimulated by IL-1 and lipopolysaccharide but not by UV irradiation, tumor necrosis factor-alpha or by interferon-gamma. The neutrophil chemotactic activity in vivo was confirmed by the intradermal injection of the factor into guinea pigs. Blocking study with monoclonal antibodies against NAP-1/IL-8 confirmed that the neutrophil chemotactic factor is IL-8.
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PMID:Normal human epidermal keratinocyte-derived neutrophil chemotactic factor. 207 75

This paper reports an unrecognized aspect of phosphotungstic acid staining at low pH. It provides an on-section staining method in which sialic acid-containing molecules can be demonstrated in the laminae rarae of the rat glomerular basement membrane. The staining in the basement membrane became negative after perfusion with the following cations: protamine sulphate, hexadimethrine, Alcian Blue, Ruthenium Red and Toluidine Blue. Blocking was not achieved with Alcian Blue at about pH 1. The staining was also abolished after mild methylation and demethylation restored the contrast. This is suggestive of the involvement of carboxyl groups. Prior digestion with pronase, trypsin and neuraminidase rendered the laminae rarae negative, whereas hyaluronidase, chondroitinase ABC and crude heparinase were without effect. This indicates that sialic acid groups are detected by this method and that heparan sulphate does not interfere. The staining of the epithelial plasma membrane, also carrying sialic acid groups, remained positive after neuraminidase treatment. It is presumed that this method can be applied successfully for detecting changes in the sialic acid content of the laminae rarae in rat glomerular basement membranes under normal and pathological conditions.
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PMID:Demonstration of sialic acid groups in the glomerular basement membrane of the rat with phosphotungstic acid at low pH. 241 Mar 95

Mononuclear cell fibroblast interactions in the normal human lung are poorly understood. Mononuclear cells can regulate fibroblast function and blood monocytes are known to migrate to the lung and participate in pulmonary inflammation. Thus, to clarify mononuclear cell-fibroblast interactions in the normal lung, we obtained supernatants from adherent monocytes and characterized their effect on the log phase growth of human lung fibroblasts. Monocyte supernatants inhibited fibroblast growth in a dose-dependent fashion. The inhibition was the result of an approximately 16,000 MW soluble factor(s) that was heat stable, trypsin sensitive, and chymotrypsin resistant. Elaboration of the factor(s) required monocyte protein synthesis and was not restricted to a density-defined monocyte subpopulation. The inhibitory capacity of a monocyte supernatant was directly related to its ability to stimulate fibroblast prostaglandin production. Blocking fibroblast prostaglandin production reversed the inhibition of fibroblast growth caused by monocyte supernatants. Thus, monocyte inhibition of fibroblast growth may be mediated by fibroblast prostaglandin production. Recruitment of monocytes to the lung and subsequent monocyte inhibition of fibroblast growth may be important in regulating pulmonary fibrosis.
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PMID:Monocyte inhibition of lung fibroblast growth: relationship to fibroblast prostaglandin production and density-defined monocyte subpopulations. 385 5

Neonatal and adult keratinocytes isolated from thin sections of split-thickness skin by trypsin-release show a preferential and strong attachment to collagen when compared to plastic, fibronectin-coated plastic, glass, or agar gels. We have investigated the reactive groups of keratinocytes and collagen required for this interaction and have determined the kinetics of attachment. At 37 degrees C both neonatal and adult keratinocytes show a rapid and irreversible attachment to collagen, reaching a plateau phase at 30-60 minutes. The cells cannot be replaced from the gel by extensive washing or by conditions normally expected to break ionic bonds. Chilling to 0 degree C before plating completely inhibits attachment, and heating at 37 degrees C reverses the inhibition. One cycle of freezing and thawing of cells inhibits the interaction. Removal of sialic residues from keratinocytes before plating with neuraminidase, or oxidation of sugars with periodate, does not inhibit attachment or growth, indicating that cell carbohydrates are not required for interaction with collagen. Neither denaturation of collagen with 8 M urea nor oxidation of sugar side chains on the gel with periodic acid affects attachment or growth. However, reaction of free-SH groups with iodoacetic acid or -NH2 groups with dinitrofluorobenzene of the gel completely inhibits growth. Blocking the guanidyl residues of collagen arginine with cyclohexanedione markedly alters all aspects of attachment, growth, and morphology, producing new and completely unique growth patterns. These studies indicate that specific chemical groups on collagen affect keratinocyte-matrix interactions and that the availability of specific residues in collagen directly influences growth and maturation. Most vertebrate cells remain closely associated with extracellular collagenous substances throughout their lifespan. The collagen may be present in both collagen fibers and in reticular fibers as well as in basement membranes. The way cells interact with and are anchored to these various substrata influences a number of important cellular functions including growth and maturation and the synthesis of extracellular matrix components. Skin epithelial cells display a particularly striking and strong dependence on collagen for growth. When plated on a collagen gel, the plating efficiency and growth is increased several-fold compared to other substrates such as glass, plastic, or agar. More recently, the initial observations on the selective attachment of keratinocytes to collagen gels have been extended by Murray et al., who demonstrated that guinea pig keratinocytes show increased plating efficiencies on Type IV collagen gels. In these studies, we have examined the mechanisms for keratinocyte-collagen interaction, and described the kinetics of attachment, the reactive sites on the cell and collagen, and the effects of chemical modification of collagen on the expression of the keratinocytes phenotype.
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PMID:Effect of chemical modification of keratinocytes and collagen in keratinocyte-collagen interactions. 723 89

Serum clearance of alpha 2M-Me or alpha 2M-Tr is rapid and identical. Alpha 2M-Tr is almost exclusively taken up in the liver by the parenchymal cells; the uptake of alpha 2M-Me is equally shared between endothelial and parenchymal cells. Blocking the scavenger receptor on endothelial cells by polyinosinic acid reduces the uptake of alpha 2M-Me to 40% of the control value; under these conditions, alpha 2M-Me is only associated with the parenchymal cells. These results show the following: (1) activation of alpha 2M by methylamine or trypsin is different; (2) the scavenger receptor on endothelial cells functions as a system for the uptake of alpha 2M-Me in addition to the specific alpha 2M receptor on parenchymal cells.
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PMID:Uptake of methylamine-activated alpha 2-macroglobulin by rat liver. 752 15

1. Tissue kallikrein (TK) cleaves low molecular weight kininogen (LK) at two sites to release kallidin: site I (between Arg389 and Ser390) is a typical cleavage point for a trypsin-like enzyme whereas site II (between Met379 and Lys380) is unusual and unique to TK. In order to learn more about the structural requirements and mechanism of cleavage at site II, we studied the hydrolysis by TK of several synthetic LK fragments varying in length between 4 and 22 residues and containing either site II only or both sites I and II. 2. Blocking site I cleavage in LK fragments by substituting DArg for LArg at position 389 or omitting site I from the sequence still allowed cleavage to proceed at site II. Replacement or deletion of selected amino acid residues in these fragments demonstrated that the presence of Arg381 was essential for site II cleavage to occur whereas Pro383, Phe385 and Ser386 could be replaced with Ala without affecting binding or cleavage by TK. Ki values towards TK were determined for all LK fragments in order to compare their binding affinities to the enzyme. Short peptides containing site II only exhibited high Ki values (> or = 100 microM) whereas longer fragments containing both sites I and II had Ki values of 2-7 microM. 3. In order to bring sites I and II into close proximity spatially and thus facilitating efficient cleavage in the enzyme-substrate complex, we prepared several cyclic analogs of the longer LK fragments.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cleavage of human kininogen fragments at Met-Lys by human tissue kallikrein. 774 84

Mycobacterium leprae heat-shock proteins hsp65 and hsp18 have received immense attention as major T-cell target antigens in leprosy. Both of these hsps and their tryptic fragments were characterized for their ability to stimulate CD4+ T cells derived from polar leprosy cases and healthy contacts. The optimal digestion of hsps with trypsin yielded four fragments of hsp65--TDB65-1 (24 kDa), TDB65-2 (18 kDa), TDB65-3 (17 kDa), TDB65-4 (14 kDa)-- and three of hsp18--TDB18-1 (10 kDa), TDB18-2 (5 kDa), TDB18-3 (3 kDa). While all of these tryptic fragments and undigested hsps triggered CD4+ T cells from tuberculoid (TT) leprosy patients and healthy contacts (SI > 2), only two fragments--TDB65-2 and TDB18-3--were found to be stimulatory in anergic lepromatous (LL) leprosy patients (SI = 5.27 and 3.0, respectively). Blocking studies using allele-specific anti-DR monoclonal antibodies revealed multiple HLA-Dr restriction, with DR2 providing the strongest restriction in both TT as well as LL leprosy. These findings indicate that M. leprae hsps and their trypsin-digested fragments are promiscuous and recognizable in the context of diverse HLA alleles, of which DR2 is the most efficient restriction element. The 18-kDa fragment of hsp65 and the 3-kDa fragment of hsp18 are the most versatile fragments that could elicit in vitro proliferation in both polar forms of leprosy.
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PMID:CD4+ T-cell responses to recombinant hsp65 and hsp18 of M. leprae and their trypsin-digested fragments in leprosy: diversity in HLA-DR restriction. 864 14

Thiostrepton is a highly modified multicyclic peptide antibiotic synthesized by diverse bacteria. Although best known as an inhibitor of protein synthesis, thiostrepton is also a potent activator of gene expression in Streptomyces lividans. In these studies, we characterize the nature of the interaction between thiostrepton and two proteins that it induces, TipAL and TipAS. In the absence of added cofactors, thiostrepton formed a complex with either TipAL or TipAS in aqueous solution. The TipA-thiostrepton complex was not dissociated by denaturants such as SDS, urea, or disulfide reducing agents. The mass of the TipAS-thiostrepton complex as determined by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry (MS) was equivalent to the sum of TipAS and thiostrepton. Thiostrepton also reacted spontaneously with free cysteine (but not with other amino acids tested) to generate stable compounds having masses equivalent to thiostrepton plus 3 to 4 cysteines. Blocking experiments indicated that complex formation required dehydroalanine residues on thiostrepton and cysteine residues on TipAS. When the TipAS-thiostrepton complex was digested with trypsin and analyzed by MS, the thiostrepton adduct was found bound only to the unique cysteine-containing TipAS peptide fragment. Amino acid analysis confirmed that the TipAS-thiostrepton complex contained lanthionine, the product of a reaction between dehydroalanine and cysteine. Together, these data document a covalent attachment of thiostrepton to TipA proteins mediated by bond formation between dehydroalanine of thiostrepton and cysteine of TipAS. Implications regarding the function of TipAS as a thiostrepton (electrophile)-sequestering protein and thiostrepton-mediated activation of TipAL as a model of irreversible transcriptional activation are discussed.
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PMID:Characterization of the covalent binding of thiostrepton to a thiostrepton-induced protein from Streptomyces lividans. 865 74


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