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)

lac repressor can be dissected by trypsin into a homogenous tetrameric core (accounting for residues 60 to 347), carrying inducer binding activity, and the monomeric amino-terminal peptides ("headpieces") accounting for residues 1 to 59 and 1 to 51, respectively. This restriction of the action of trypsin on lac repressor is obtained in 1 M Tris-HCl (pH 7.5)-30% in glycerol at 25 degrees C since only the peptide bonds at lysine-59 and to a lesser extent after at arginine-51 are cleaved under these conditions. The headpieces can be purified by gel filtration. They have ordered secondary structure as revealed by circular dichroism studies. The monomeric headpieces show the relatively weak binding to nonoperator DNA but not the highly specific and strong binding to operator DNA typical for tetrameric lac repressor.
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PMID:Isolation of amino-terminal fragment of lactose repressor necessary for DNA binding. 32 Oct 12

The DNA polymerase in crude extracts of Drosophila melanogaster embryos sedimented at 9.0, 7.3, and 5.5 S on glycerol velocity gradients. The relative proportions of these enzymes depended on the method used to prepare the extract. Extracts of whole embryos contained the 7.3S and the 5.5S DNA polymerases and extracts of dechorionated embryos contained the 9.0S and 7.3S DNA polymerases. The porportion of the 5.5S DNA polymerase increased relative to the 7.3S DNA polymerase during storage of the extract of whole embryos. The protease inhibitor, phenylmethanesulfonyl fluoride, inhibited the formation of the 5.5S DNA polymerase, suggesting that it was proteolytically produced from the 7.3S DNA polymerase. This was demonstrated directly by converting the 7.3S DNA polymerase to the 5.5S DNA polymerase by treatment in vitro with trypsin. The degradation of the enzyme occurred without significant loss of DNA polymerase activity. It is further demonstrated that endogenous proteolysis reduced the chromatographic heterogeneity of the Drosophila DNA polymerase on diethylaminoethyl-Sephadex. When endogenous proteolysis was reduced, three forms of DNA polymerase were isolated by diethylaminoethylcellulose chromatography; two of these enzymes sedimented at 7.3S and the third sedimented at 9.0S. These results demonstrate the physical heterogeneity of the Drosophila DNA polymerase and suggest its similarity to vertebrate DNA polymerase-alpha.
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PMID:Multiple forms of Drosophila embryo DNA polymerase: evidence for proteolytic conversion. 40 23

Group A streptococci were treated with various enzymatic and chemical agents in an attempt to dissociate the type-specific M protein from intact surface "fimbriae." Mild peptic digestion at pH 5.8, which was previously shown to extract serologically active M antigen from intact streptococci had little visible effect on the fimbriae even though virtually all of the M protein was removed as demonstrated by (a) increased susceptibility to phagocytosis, (b) lack of opsonic effect of homologous M antibody on the treated streptococci, and (c) loss of HCl-extractable M protein. These fimbriated streptococci which lacked M protein adhered to human oral mucosal cells equally as well as untreated, fimbriated organisms which retained their M protein. Removal of both fimbriae and M protein by digesting organisms with HCL at pH 2.0 at 94 degrees C. or with trypsin abolished their ability to bind mucosal cells. Electron microscopy of streptococci bound to epithelial cells demonstrated fimbriae radiating from the surface of the organisms to the membrane of the epithelial cells. It is apparent, therefore, that the determinants of streptococcal fimbriae involved in resistance to phagocytosis can be dissociated from those involved in epithelial cell binding. These results are consistent with our previous studies which suggested that fatty acids ester linked with glycerol teichoic acid rather than M protein of streptococci binds the organisms to epithelial cells.
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PMID:Epithelial cell binding of group A streptococci by lipoteichoic acid on fimbriae denuded of M protein. 76 4

Acid-fast bacilli multiplied in liquid culture media containing hyaluronic acid when inoculated with mycobacteria from a lepromatous leprosy nodule. The culture was readily subcultured at ten day intervals in the homologue media, but failed to grow in the Dubos, Middlebrook and Lowenstein media. These findings confirm the results of Skinsnes et al (1975). Identification of this culture is not yet available, however it gives positive immunofluorescence with authentic anti-M. leprae serum. The obtained culture also grows as a chromogenic culture at 34 degrees C on a simple medium prepared from trypsin digested human umbilical cord, yeast extract powder and glycerol. This medium can be sterilized in an autoclave, but filter sterilized sheep, bovine or horse serum must be added aseptically as an essential ingredient. The medium does not differ considerably from the hyaluronic acid medium proposed by Skinsnes et al, but it is easier to prepare, it is inexpensive and permits a logarithmic growth within seven days of the so far unidentified culture isolated from leprotic nodules.
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PMID:A simplified hyaluronic acid based culture medium for mycobacteria isolated from human lepromata. 79 28

Adenovirus type 5 'cores' prepared by heating in the presence of deoxycholate and partially purified on a glycerol density gradient could be visualized as roughly isometrical particles with a condensed centre from which twisted filaments or loops of DNA emanated. This compact structure was readily dispersed by spreading on distilled water or by treatment with EDTA, Nonidet, DNase or trypsin. Spreading with Nonidet was particularly effective in unfolding the cores and revealing long filaments about 100 A thick presumably of the virus nucleoprotein. Subunits (about 30 to 60 A in diam.) could be seen free in the DNase-treated cores, suggesting a particulate nature of one or both of the core proteins.
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PMID:Electron microscopy of adenovirus cores. 80 87

The effects of pyocin S2, a bacteriocin produced by Pseudomonas aeruginosa strain M47, on several processes in susceptible bacterium have been examined. Lipid synthesis, measured in terms of [32P]phosphate, [14C]acetate or [2-3H]glycerol incorporation into lipid fractions, was halted almost completely soon after pyocin S2 addition. When cell suspensions were treated with various amounts of pyocin S2, the extent of inhibition of lipid synthesis was proportional to the ratio of killed bacteria. Protein synthesis was not essential for the inhibition. Degradation of lipid due to pyocin S2 was not detected. Pyocin S2 also affected protein and nucleic acid syntheses, but these inhibitions appeared with a delay of about 10 min after the cessation of lipid synthesis. The effect of trypsin [EC 3.4.21.4] on the viability of cells which had adsorbed pyocin S2 was also investigated: the cells went through a period when the destruction of pyocin S2 by trypsin restored the colony-forming ability of the cells (stage I). Then transition to a second state in which the cells lost viability irrespective of trypsin treatment (stage II) took place. The transition from stage I to stage II depended on the energy metabolism of the cells and followed first-order kinetics with a rate proportional to the number of killing units of adsorbed pyocin S2. The residual capacity for lipid synthesis in cells which had adsorbed pyocin S2 after trypsin treatment at various times indicated that lipid synthesis was inhibited only in the cells at stage II of pyocin S2 action.
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PMID:Preferential inhibition of lipid synthesis by the bacteriocin pyocin S2. 81 53

ATP citrate lyase was purified by two different procedures from the livers of rats first starved and then fed with a fat-deficient and high carbohydrate-glycerol diet. These enzyme preparations were judged homogeneous by sedimentation equilibrium and polyacrylamide gel electrophoresis. The molecular weight of the native enzyme was around 4.4 X 10(5) as determined by sedimentation equilibrium. On sodium dodecyl sulfate gel electrophoresis the enzyme usually showed a single protein band with an estimated molecular weight of 1.2 X 10(5). A similar value for the molecular weight of the subunit was obtained by gel filtration on 6% agarose in the presence of 6 M guanidinium chloride. The molecular weight of this polypeptide chain was estimated by sedimentation equilibrium to be around 1.1 X 10(5). These results indicated that ATP citrate lyase has a subunit structure of four polypeptides of similar size. The extinction coefficient of the dry protein and its amino acid composition are also reported. Some batches of fully active enzyme, judged to be homogeneous by sedimentation equilibrium and polyacrylamide gel electrophoresis, showed two additional major polypeptides (Mr approximately 7.1 X 10(4) and 5.5 X 10(4)) on sodium dodecyl sulfate gel electrophoresis. Studies on the polypeptides produced by proteolytic modification of the native enzyme by trypsin indicated that the additional protein bands observed on sodium dodecyl sulfate gel electrophoresis with some of the batches of enzyme could have been formed by limited proteolysis ("nicking") of the original 1.1 X 10(5) subunit. Trypsin treatment of the native enzyme did not affect the enzyme activity, whereas chymotrypsin and pronase treatment inactivated the enzyme. The trypsin-treated enzyme, which contained only the two smaller polypeptides, did not differ significantly from the untreated enzyme with respect to sedimentation behavior, phosphorylation by ATP, Km for citrate, and immunoreactivity, but it was more heat-labile than the untreated enzyme. The phosphate group on the phosphorylated "nicked" enzyme was located on the larger polypeptide fragment.
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PMID:Structure of ATP citrate lyase from rat liver. Physicochemical studies and proteolytic modification. 82 50

Previous data from this laboratory showed that certain phage group 2 staphylococci contain a large 56S virulence plasmid containing genes that code for both exfoliative toxin (ET) and a specific staphylococcin. Optimal cultural conditions for bacteriocin production were similar to those found for ET production. The bacteriocin is an extracellular product produced in small quantities that can be neither extracted from cell pellets with 1 M NaCl nor induced with mitomycin C. The staphylococcin is active against a wide variety of gram-positive organisms and also against group 2 staphylococcal strains that have been cured of the plasmid carrying the staphylococcin marker. The bacteriocin is not inactivated by oxidation, mechanical agitation, or boiling for 15 min. It is sensitive to the action of trypsin and Pronase but not lysostaphin and is stable within a pH range of 4 to 9. It has an isoelectric point of approximately 7.7. Removal of the ampholytes and glycerol from electrofocused staphylococcin preparations resulted in total loss of bacteriocin activity.
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PMID:Production and properties of a staphylococcin genetically controlled by the staphylococcal plasmid for exfoliative toxin synthesis. 87 Apr 29

The membrane-bound penicillinase of Bacillus licheniformis 749/C is a phospholipoprotein that differs from the hydrophilic exoenzyme in that its polypeptide chain carries an additional 25 residues (mostly hydrophilic) with phosphatidylserine as the NH2-terminus. To determine if other phospholipoproteins are present in the plasma membrane, the penicillinase-inducible strain 749 was grown without inducer in the presence of [2-(3)H] glycerol. Electrophoretic separation of the membrane proteins (after removal of free lipids) showed an association of 3H-activity with certain of the proteins which could not be broken by lipid solvents and strongly denaturing conditions. Pronase digestion of the membrane proteins (after solvent extraction) released phosphatidylserine, thus indicating the covalent linkage of protein and phospholipid. Treatment of the isolated membranes with trypsin solubilized the protein portion of some of the phospholipoproteins (as with penicillinase), but not the 3H-labelled fragment. Penicillinase should be considered as the first observed example of a group of phosphatidylserine-containing proteins present in the plasma membrane of B. licheniformis 749 and 749/C.
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PMID:Membrane associated phospholipoproteins of Bacillus lichenformis 749. 97 40

Cells, obtained from human leg by successive treatments with trypsin, were air dried on microscope slides before mounting in glycerol. Dry weights and projected areas of individual cells were measured using a Vickers M 86 scanning microinterferometer. The dry weights of cells varied from 100 pg for basal cells to 700 pg for large squames. Corresponding projected areas varied from 100 to 1500 mum2.
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PMID:Changes in dry weight and projected area of human epidermal cells undergoing keratinization as determined by scanning interference microscopy. 100 8


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