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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 (M.) mobile 163K isolated from fish was investigated for its hemadsorbing, hemagglutinating, and hemolysing capacities and for its ability to adhere to erythrocytes. Hemadsorption to the colonies of M. mobile occurred with ovine, bovine, equine, trout, and carp erythrocytes and was inhibited by treatment of the mycoplasmas with substances acting on proteins (pronase, trypsin, glutaraldehyde), heat, UV-irradiation and homologous antiserum. Hemadsorption could be prevented also by treatment of the erythrocytes with neuraminidase. In liquid medium ovine erythrocytes were agglutinated and afterwards lysed by M. mobile. The erythrocytes which were adsorbed to the colonies of M. mobile were finally lysed also. Darkfield preparations showed the ability of M. mobile to adhere to erythrocytes and also its hemagglutinating properties.
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PMID:Interaction of Mycoplasma mobile 163K with erythrocytes. 343 86

The following modifications in the lipid composition of Mycoplasma gallisepticum or M. capricolum membranes led to changes in the rates of [14C]cholesterol and [14C]phospholipid exchange between cell membranes and an excess of small unilamellar vesicles: 1) increase in the cholesterol/phospholipid molar ratio from 0.25 to 0.92; 2) incorporation of synthetic, cross-linked phosphatidylethanolamine (PE) derivatives, 3) incorporation of sphingomyelin (SPM); and 4) increase in the phosphatidylglycerol/cardiolipin ratio of M. capricolum cell membranes by supplementing the growth medium with 0.5 mM CaCl2 CaCl2, and decrease in this ratio by supplementing the growth medium with 0.5 mM CaCl2 and 20 micrograms/ml egg phosphatidylcholine or with isopalmitic acid. The rates of radiolabeled lipid exchange decreased when the content of cholesterol, cross-linked PE, or SPM increased, indicating an inverse correlation between exchange rate and membrane lipid order. This is consistent with an exchange mechanism that involves the slow dissolution of the lipid from the surface of the donor particle. Lipidic particles appeared in trypsin-treated M. capricolum membranes obtained from cells grown with both Ca2+ and PC, whereas the hexagonal-II phase appeared in membranes from cells grown with Ca2+. Cholesterol and phospholipid exchange rates were enhanced under the conditions in which the bilayer structure was destabilized by transitional states between the lamellar and hexagonal-II phases. Thus, mycoplasmas are well suited for examination of the influence of membrane lipid composition on rates of lipid exchange between membranes.
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PMID:Kinetics of cholesterol and phospholipid exchange between mycoplasma membranes and lipid vesicles. 366 16

The relation between Mycoplasma pulmonis-mediated hemolysis and translocation of a unique fluorescent cholesterol probe was examined. The probe, cholesteryl 12(4-methyl-7-nitrobenz-2-oxa-1,3-diazole) dodecanoate, had fluorescent properties, which permitted microscopic assessment of probe transfer. Significant translocation occurred only after trypsin treatment of the erythrocyte, and the rate of transfer was increased in the presence of bovine serum albumin. This correlated with the previously reported hemolytic activity of M. pulmonis, thus relating the two activities and permitting their integration into a mycoplasma-eukaryotic cell-cell interaction model.
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PMID:Correlation of Mycoplasma-pulmonis-mediated hemolysis with translocation of a fluorescent cholesterol probe. 366 23

Mycoplasma pulmonis has substantial DNase activity exposed on the cell surface. At least part of this activity is attributable to an endonuclease. The activity is destroyed at 56 degrees C and inhibited by either 5 mM EDTA or 10 mM zinc chloride. It can also be eliminated by treatment of intact organisms with trypsin and is regenerated by incubation of the treated organisms in a medium that supports protein synthesis. DNase exposed at the cell surface constitutes 20% of the total DNase activity present in M. pulmonis extracts.
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PMID:Identification and preliminary characterization of external membrane-bound nuclease activities in Mycoplasma pulmonis. 394 Oct 2

The attachment of Mycoplasma pulmonis m53 organisms to mouse and rat synovial cells was examined by using the organisms and the synovial cells treated in various ways. M. pulmonis treated with trypsin attached to the synovial cells, but the organisms treated with pronase, formaldehyde, glutaraldehyde, or heat did not. These findings suggest that the sites for binding M. pulmonis to the mouse and rat synovial cells are of polypeptide nature. Treatment of M. pulmonis with sialic acid and treatment of the synovial cell sheets with neuraminidase did not affect the attachment. The synovial cell surface for receptors M. pulmonis organisms would be different from those on respiratory cells or erythrocytes for M. pneumoniae or M. gallisepticum. Even nonviable organisms and M. pulmonis membranes attached to the mouse or rat synovial cells. The nature of the receptor of mouse synovial cells would be different from that of rat cells, since rat cells were affected by treatment with formaldehyde or glutaraldehyde, but mouse cells were not.
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PMID:Attachment of Mycoplasma pulmonis to rat and mouse synovial cells cultured in vitro. 408

Interferon was induced in mice after intraperitoneal inoculation with four different mycoplasmas. Peak levels of between 100 and 300 U of interferon per ml were attained by 6 h postinfection with each of the mycoplasmas except Mycoplasma arthritidis, which induced higher titers (400 to 11,800 U/ml) by this time. A fifth mycoplasma, M. pulmonis, induced interferon inconsistently and at a later (72 to 96 h) time. Mycoplasmatales virus MVL51 and sterile mycoplasmal broth did not stimulate interferon production in vivo. All of the mycoplasmas and MVL51 failed to induce interferon in murine spleen cell, peritoneal exudate cell, or peripheral blood leukocyte cultures. Preinfecting the mycoplasmas with MVL51 or treating the organisms with trypsin or dilutions of specific antisera did not enhance their ability to induce interferon in vitro.
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PMID:Induction of interferon in mice by mycoplasmas. 437 95

A recent isolate of Mycoplasma fermentans (strain K10, from human leukemic bone marrow) induced a lethal toxicity syndrome in mice. High doses of both viable and inactivated cells were toxic when injected intraperitoneally. Whole lysates and membranes from osmotically shocked cells killed mice, but cytoplasm did not. When membranes were dissolved in detergents and reaggregated by dialysis in the presence of Mg(2+), the lipid-protein complex thus formed was toxic. Lipids extracted from membranes with chloroform-methanol did not kill mice. Protein-rich fractions (obtained by reaggregation plus acetone washes or ammonium sulfate precipitation of dissolved membranes) were also not toxic. No qualitative differences in proteins from three toxic isolates and three nontoxic laboratory strains of M. fermentans were detectable by polyacrylamide gel electrophoresis. The toxic factor contained in reaggregated membranes was heat-stable but sensitive to Pronase, trypsin, and lipase.
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PMID:Toxic membrane fractions from Mycoplasma fermentans. 515 2

The cytoplasmic membrane of Mycoplasma laidlawii strain B is solubilized by anionic and nonionic detergents, succinylation, phospholipase A, alkaline phosphatase, trypsin, and chymotrypsin. Cationic detergents are without effect, as are chelating agents, even in the presence of high concentrations of monovalent cation. The detergent-solubilized membrane exhibits one peak in the analytical ultracentrifuge, but the sedimentation coefficient is dependent upon concentration of detergent. Simple dialysis does not remove all of the sodium dodecylsulfate except from lipid-depleted membrane particles. Membranes bind sodium dodecylsulfate but acetone powders of membranes do not. Sulfated alcohols with chain lengths of C(14) and C(16) are more tightly bound than dodecylsulfate. A constant amount of di- and trivalent cation is bound by the membrane upon aggregation. Only a portion of this cation is removable with chelating agents. No chelating agent is bound by these aggregates. A portion of the lipid-depleted membrane particles is solubilized by negatively charged lipids and detergents, giving rise to aggregates in the presence of divalent cation. Fractionations of detergent-solubilized membranes by preparative gel electrophoresis and ammonium sulfate were inconclusive. Density gradient centrifugation of succinylated membranes yielded at least five fractions which exhibited homogeneity by ultracentrifugation. Analytical gel electrophoresis of these fractions demonstrated heterogeneity. The composition of these five fractions suggested separation of protein from lipid.
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PMID:Observations on membranes of Mycoplasma laidlawii strain B. 536 Dec 9

Rolling disease has been produced and studied in rats and mice, using the exotoxin of the A strain of Mycoplasma neurolyticum. The primary lesion of the brain consists of spongiform degeneration, associated with vesicle formation in the cortex and underlying white matter of the cerebral hemispheres, and in the molecular layer of the cerebellum. The brains of animals surviving 2 days or longer show extensive necrotizing lesions resembling ischemic necrosis, in both cerebral hemispheres. The brains of rats and mice with rolling disease become deeply stained by intraperitoneally injected trypan blue, indicating early disruption of the blood brain barrier. The toxin appears to be a thermolabile protein with a molecular weight exceeding 200,000. It is only active when injected by vein, and causes no disease when injected intracerebrally, intraperitoneally or subcutaneously, suggesting the existence of specific receptors within the vascular bed of the central nervous system. Protection is afforded by rabbit antibody against the toxin, but only when antibody is injected within less than 3 min after intravenous injection of toxin, indicating rapid fixation to receptors in the brain. The toxin is inactivated by incubation for 10 min at 37 degrees C with suspensions of the sedimentable component of normal brain. The inactivating factor in brain sediment is very thermostable, not affected by trypsin, and eliminated by treatment with periodate. Similar inactivation of toxin is demonstrable with water-soluble gangliosides of brain. A theoretical concept to explain the action of the toxin is proposed.
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PMID:Studies of PPLO infection. II. The neurotoxin of Mycoplasma neurolyticum. 592 13

A receptor specific for lipoglycans from Acholeplasma axanthum and Acholeplasma granularum was isolated from sheep erythrocyte stroma by extraction with n-pentanol and permeation chromatography. The purified receptor appeared as one band on sodium dodecyl sulfate-polyacrylamide gels and stained with Coomassie blue, periodate-Schiff reagent, and Sudan black. It was distinct from the erythrocyte receptor for gram-negative lipopolysaccharides and the glycophorin receptor for certain species of Mycoplasma. Periodate oxidation and trypsin did not affect the receptor activity in intact erythrocytes, but the purified receptor was susceptible to proteolytic digestion. Specific receptors, sensitive to trypsin digestion, could be isolated from rabbit kidney and cultured rabbit epidermal cell membranes. These could be distinguished from the receptor from erythrocytes by their solubility in n-pentanol. The segment of the lipoglycan molecule which binds to these receptors was not lipoidal in nature and was distinct from the specific antigenic determinants of the lipoglycans.
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PMID:Isolation and characterization of the sheep erythrocyte receptor for acholeplasmal lipoglycans. 618 20


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