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)

Mycoplasma pneumoniae initiates infection in the human host by attachment to respiratory epithelium. The organism attaches by a specialized terminal structure. Monoclonal antibodies to an organism surface protein (P1) inhibited attachment to respiratory epithelium and were localized to the tip structure by a ferritin antibody label. The P1 protein was degraded by trypsin treatment to smaller polypeptides that possessed the same antigenic determinants as the larger P1 protein when reacted with the specific monoclonal antibody, and evidence has been provided for the existence of multiple antigenic determinants on the attachment protein.
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PMID:Location of attachment moiety on Mycoplasma pneumoniae. 620 59

Mycoplasma offer several unique advantages for investigating the mechanism controlling transfer and uptake of exogenous cholesterol and phospholipids by biomembranes, as their plasma membrane interacts directly with exogenous lipid donors and their endogenous lipid synthesis is restricted. Growing cells of five species of Mycoplasma were found to take up significant quantities of phosphatidylcholine and sphingomyelin as well as free and esterified cholesterol. In contrast, growing cells of three species of Acholeplasma failed to take up any of the exogenous phospholipids and incorporated only low amounts of free cholesterol and no esterified cholesterol. It is hypothesized that Mycoplasma species have receptors for serum lipoproteins and phospholipid-cholesterol vesicles that facilitate the transfer of cholesterol and phospholipids to the growing cell membrane. Our finding that gentle trypsin treatment of growing Mycoplasma capricolum cells decreased their cholesterol uptake ability by about 50% but did not affect cholesterol uptake by growing Acholeplasma laidlawii cells appears to support the existence of protein receptors for lipoproteins on the surface of Mycoplasma but not on Acholeplasma species. Digestion of membrane phospholipids by phospholipase A2 decreased the cholesterol-binding capacity of isolated A. laidlawii and M. capricolum membranes, roughly in proportion to the amount of phospholipid digested. The total removal of phosphatidylglycerol and diphosphatidylglycerol from A. laidlawii membranes by phospholipase A2 only decreased but did not abolish cholesterol uptake, an indication that glycolipids also participate in cholesterol uptake.
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PMID:Cholesterol and phospholipid uptake by mycoplasmas. 628 8

A library of cloned Mycoplasma hyorhinis genomic sequences was constructed by incorporation of EcoRI digestion fragments of mycoplasma DNA into the lambda Charon 4A bacteriophage vector. Immunological screening of recombinant phage plaques identified clones containing genes encoding mycoplasma antigenic structures expressed in an Escherichia coli host. Two such recombinant phage isolates, lambda Ch4A-MhrG1 and lambda Ch4A-MhrG28, were defined and found to contain distinct genomic sequences by analysis of restriction endonuclease fragments. Inoculation of mice with recombinant gene products from lambda Ch4A-MhrG1 yielded antiserum selectively recognizing a Mr 29,500 trypsin-sensitive mycoplasma constituent. This established a means for producing selected immunogenic mycoplasma component in a bacterial host. The cloned genomic sequences of M. hyorhinis encoding expressed mycoplasma antigens represent molecular probes that can be characterized both by specific DNA sequences and by the antigenic structure of corresponding gene products. These genomic fragments define initial physical markers of the M. hyorhinis genome and may be useful in assessing antigenic and molecular genetic relationships within the genus Mycoplasma and among other members of the class Mollicutes.
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PMID:Cloned genomic DNA sequences from Mycoplasma hyorhinis encoding antigens expressed in Escherichia coli. 634 24

All of 14 serotype standards and 34 of 35 wild-type strains of Ureaplasma urealyticum isolated from humans demonstrated an immunoglobulin A (IgA) protease activity. This activity degraded radiolabeled human IgA including IgA1 but not IgG or azocasein. The IgA fragments were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by radioautography, and they had molecular weights of about 110,000 and 50,000. The IgA protease activity persisted in 25 mM EDTA but was sensitive to trypsin; it was presumed to be protein. This is the fourth microbial genus and the first myocoplasma species in which an IgA protease activity has been identified. Such activity was absent in Mycoplasma pneumoniae, Mycoplasma hominis, and Acholeplasma laidlawii.
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PMID:Immunoglobulin A protease activity of Ureaplasma urealyticum. 636 62

The immune response of experimentally infected hamsters and human patients to Mycoplasma pneumoniae was examined by radioimmunoprecipation in conjunction with gel electrophoresis and fluorography. Both intrinsically and extrinsically labeled mycoplasma proteins were coincubated with acute and convalescent sera in a radioimmunoprecipitation assay. Two M. pneumoniae proteins were selectively precipitated by convalescent sera. These predominant immunogens were trypsin-sensitive, antibody-accessible surface proteins that co-migrate on polyacrylamide gels with proteins P1 and P2, which were previously implicated by us as mediators of cytadsorption. Anti-M. pneumoniae antiserum did not precipitate radiolabeled antigens derived from Mycoplasma orale or Mycoplasma salivarium. These data indicate that M. pneumoniae infection stimulates a specific and highly targeted host antibody response to key proteinaceous immunogens.
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PMID:Host discrimination of Mycoplasma pneumoniae proteinaceous immunogens. 640 96

Haemadsorption-negative mutants of Mycoplasma pneumoniae were isolated which varied in their capacity to adsorb erythrocytes of various animal species suggesting adherence to erythrocytes is mediated by different binding mechanisms. Trypsin treatment of the wild-type strain resulted in loss of haemadsorbing activity; several polypeptides, some of which regenerated with haemadsorbing activity following further incubation, were also trypsin sensitive. The haemadsorption-negative mutants could be divided into two groups according to their polypeptide pattern. In the first group (11 mutants) the PAGE pattern was identical to that of the wild-type strain. The second group comprised 7 mutants which differed from the wild-type by lack of one or more polypeptides with molecular weights of 190 000, 90 000 or 40 000. During growth attachment to glass was weak or absent in the mutants. Surface hydrophobicity as measured by hydrophobic-interaction chromatography was nearly comparable in mutants and parent strain.
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PMID:Analysis of polypeptides of mutants of Mycoplasma pneumoniae that lack the ability to haemadsorb. 640 87

The mechanism(s) of interaction between Mycoplasma pulmonis and eucaryotic cells was studied by adherence to and hemagglutination of erythrocytes. Simple and complex carbohydrates and glycoproteins were unable to inhibit either adherence or hemagglutination, indicating that neither was a lectin activity. Both interactions appeared to be hydrophobic due to their requirement for salt and their sensitivity to temperature. Hemagglutination, but not adherence, was inhibited by both trypsin and glutaraldehyde treatment of the mycoplasma, suggesting that adherence and hemagglutination are qualitatively different. The erythrocyte receptor sites for the two activities were also separable since hemagglutination, but not adherence, required trypsinization of erythrocytes. The hemagglutinin was shown to be an integral mycoplasma component and not a broth contaminant. Once removed, hemagglutinating activity could not be replenished by incubation in serum or broth at 4 degrees C, but could be regenerated during protein synthesis under nonreplicative conditions. Thus, a mycoplasma membrane protein was detected which was capable of interacting with opposing membrane surfaces through hydrophobic interactions. Consequently, a multiphasic model of M. pulmonis-eucaryotic cell interactions was proposed.
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PMID:Multiphasic interactions of Mycoplasma pulmonis with erythrocytes defined by adherence and hemagglutination. 671 40

Mycoplasma pneumoniae must attach to respiratory tract cells to cause primary atypical pneumoniae. The attachment process involves a receptor site on the external membrane surface of the host cell and a specialized attachment tip on the mycoplasmal cells. Attachment to lung fibroblasts and ciliated tracheal explants is time dependent, with maxima reached in 45-90 min at 37 C. Attachment to ciliated cells is slower, apparently because of continuous ciliary motion. Normally, less than 10% of available mycoplasmas become cell associated in vitro, perhaps because the pathogen must be in a particular growth phase or because only a small fraction of the M. pneumoniae population has complete or effective attachment tips. Mycoplasmas that attach to host cells normally have the constricted attachment tip oriented toward the host cell surface. Mycoplasmas are oriented vertically in cultures of densely ciliated cells, but can lie horizontally alone--and in close apposition to--cell membranes of sparsely ciliated or nonciliated cells. The site to which M. pneumoniae attaches, a sialoglycoprotein, is readily inactivated by neuraminidase, partially sensitive to pronase, and resistant to trypsin. Purified glycoprotein extracts bind to M. pneumoniae.
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PMID:A review of the morphological and biochemical features of the attachment process in infections with Mycoplasma pneumoniae. 681 1

The cilia-stopping effect of mycoplasmas of human and various animal origin in mouse and chicken tracheal organ cultures was studied. From the results in mouse tracheal organ cultures, the mycoplasma strains tested were divided into three groups: Mycoplasma pulmonis m53, M pulmonis JB, M. pulmonis OK, M. mycoides subsp. Mycoides PGl and M. Gallisepticum S6 showed a strong cilia-stopping effect; M. pulmonis PG22, M. mycoides subsp. capri PG3, M. meleagridis 19729, M. neurolyticum Type A and M. arthritidis PG6 showed a mild effect; and M. pneumoniae FH, M. salivarium Hup, M. hominis type 1-C and M. orale N-C human origin and Acholeplasma laidlawii PG8 showed a weak effect. On the other hand, in chicken tracheal organ cultures, only M. gallisepticum S6 showed a strong effect, M. meleagridis 19729 was affected to a lesser degree, and the other mycoplasma strains showed a weak or no effect. The results indicate that some murine and poultry mycoplasmas showed a cilia-stopping tendency in mouse and chicken tracheal organ cultures, respectively, while human mycoplasmas showed weak or little effect in both organ cultures. In mouse tracheal organ cultures, M. pulmonis m53 treated with heat, trypsin or formaldehyde, and the sterile filtrate of an m53 broth culture showed no cilia-stopping effect. The relationship of the pathogenicity of mycoplasmas for their natural hosts to that for cultured respiratory cells is discussed.
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PMID:Comparison of ciliostasis by mycoplasmas in mouse and chicken tracheal organ cultures. 708 99

During studies of human hematopoietic cells, two novel anti-mycoplasma monoclonal antibodies reacting in human cell surface binding assays were generated. These monoclonal antibodies define antigens (called MP71 and MP33) that showed variable positive and negative expression in different cultures of the same human cell lines. Furthermore, negative cell cultures could be converted to positive cultures upon incubation with filtered media from a previously positive cell culture. A DNA staining assay was used to demonstrate the presence of mycoplasma in the cultures positive for MP71. The expression of MP71 on a panel of cell lines always correlated with the expression of MP33, suggesting that the latter antigen is also mycoplasma related. The monoclonal antibodies against both antigens (MP71 and MP33) were each able to block the growth of mycoplasma newly transferred to hematopoietic cell cultures. Biosynthesis of these mycoplasma antigens differed from biosynthesis of host cell surface antigens in that the former showed a relative insensitivity to gamma irradiation. Internal labeling with 35S-methionine or host cell surface labeling with 125I and analysis by immunoprecipitation showed that the antigens MP71 and MP33 had sizes of Mr 71,000 and 33,000, respectively. Also the antigen MP71 was almost completely, although transiently, cleared from the host cell surface by trypsin. Growth inhibition analysis of different mycoplasma species indicated that the monoclonal antibody recognizing MP71 was uniquely reactive with Mycoplasma hyorhinis.
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PMID:Monoclonal antibodies reacting with immunogenic mycoplasma proteins present in human hematopoietic cell lines. 714 4


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