Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of plasmid-encoded resistances in regenerating protoplasts of Bacillus subtilis occurs only after wall synthesis has been resumed. This is observed for protoplasts obtained from cells already containing plasmids (pC194, pT127, pK545) or for plasmid-bearing cells coming from a PEG-mediated transformation. Recovery of expression needs a 2-h incubation of protoplasts, previously washed to get rid of their lysozyme content, in rich hypertonic medium (SMMP). A longer incubation (24-h) results in the obtention of regenerants; however, most of them have lost their resistant phenotype in contrast to those obtained from the usual solid regeneration plates. This finding suggests either a high curing effect or some kind of gene inactivation phenomenon. Discussion is focused on the critical points that have to be considered when polyethylenglycol-mediated transformation of protoplasts is applied to recombinant DNA technology.
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PMID:Expression and maintenance of plasmid resistance in regenerating protoplasts of Bacillus subtilis. 314 Aug 46

We have measured the rates of isotope exchange at the nitrogen of the indole ring of Trp-63 of lysozyme and of L-tryptophan as a function of solution viscosity. We have used two cosolvents, glycerol and ethylene glycol, to modify the relative viscosity. We have derived the appropriate kinetic equations for the alternative possibilities that the exchange takes place either in solution or in the intact protein matrix. Because we chose to study the proton-catalyzed exchange reaction, the rate of it is not expected to be diffusion-limited. We confirmed this by measuring the exchange from tryptophan. These results and the known effects of glycerol and ethylene glycol on the solvation of indole allow us to predict that if the exchange reaction takes place in a protein matrix the effects of the two cosolvents when compared under isoviscous conditions should be identical. This is what we find for Trp-63 in lysozyme at 15, 20 and 26 degrees C. The slope of the linear plot of log k vs. log relative viscosity is 0.6. This strongly supports a model for conformational fluctuations where transient solvation takes place without major changes in protein folding. The most interesting feature of our findings is the fact that a slow reaction admittedly not diffusion-limited shows, when taking place in a protein matrix, a linear dependence on solution viscosity. We suggest that what we observe is the effect of damping of movement of the side chain expressed as a change in the friction along the reaction coordinate in the corresponding phase space. The presence of such effects stresses the validity and usefulness of Kramers model of rate processes for reactions taking place in a protein matrix. Such behavior is predicted by several of the recently proposed general mechanisms of enzyme catalysis.
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PMID:Viscosity and transient solvent accessibility of Trp-63 in the native conformation of lysozyme. 323 7

Thermal unfolding of ribonuclease, lysozyme, chymotrypsinogen, and beta-lactoglobulin was studied in the absence or presence of poly(ethylene glycols). The unfolding curves were fitted to a two-state model by a nonlinear least-squares program to obtain values of delta H, delta S, and the melting temperature Tm. A decrease in thermal transition temperature was observed in the presence of poly(ethylene glycol) for all of the protein systems studied. The magnitude of such a decrease depends on the particular protein and the molecular size of poly(ethylene glycol) employed. A linear relation can be established between the magnitude of the decrease in transition temperature and the average hydrophobicity of these proteins; namely, the largest observable decrease is associated with the protein of the highest hydrophobicity. Further analysis of the thermal unfolding data reveals that poly(ethylene glycols) significantly effect the relation between delta H degrees of unfolding and temperature for all the proteins studied. For beta-lactoglobulin, a plot of delta H versus Tm indicates a change in slope from a negative to a positive value, thus implying a change in delta Cp in thermal unfolding caused by the presence of poly(ethylene glycols). Results from solvent-protein interaction studies indicate that at high temperature poly(ethylene glycol) 1000 preferentially interacts with the denatured state of protein but is excluded from the native state at low temperature. These observations are consistent with the fact that poly(ethylene glycols) are hydrophobic in nature and will interact favorably with the hydrophobic side chains exposed upon unfolding; thus, it leads to a lowering of thermal transition temperature.
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PMID:Thermal stability of proteins in the presence of poly(ethylene glycols). 342 6

We report the preparation, crystallization and preliminary X-ray crystallographic study of the Fab fragment from a heteroclitic murine (BALB/c) monoclonal anti-hen egg-white lysozyme antibody complexed with a heterologous antigen, pheasant lysozyme. The complex between the heterologous antigen and the antibody has been crystallized from polyethylene glycol 8000 solutions in a form suitable for X-ray crystallographic studies. The crystals are monoclinic, space group C2 with a = 158.2 A, b = 49.1 A, c = 177.6 A, beta = 92.0 degrees (1 A = 0.1 nm).
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PMID:Preliminary crystallographic study of a complex between an heteroclitic anti-hen egg-white lysozyme antibody and the heterologous antigen pheasant egg-white lysozyme. 368

We report on the preparation, crystallization, and preliminary x-ray crystallographic study of the Fab fragments of two monoclonal anti-2-phenyloxazolone antibodies obtained from the secondary response to this hapten. The Fab fragment from one of these (NQ10/12.5) has been crystallized from polyethylene glycol 8000 solutions in a form suitable for high-resolution x-ray crystallographic studies. These crystals are monoclinic, space group C2, with a = 129.2 A, b = 79.4 A, c = 57.7 A, beta = 96.2 degrees, and one Fab/asymmetric unit. Determination of the three-dimensional structure of Fab NQ10/12.5 should help clarify the role of somatic mutation in the maturation of an immune response. This antibody and an anti-lysozyme antibody also under study apparently use the same germ-line encoded VK and a similar VH gene, respectively, as the idiotypic anti-oxazolone antibodies characteristic of the primary response. A comparative study of the two structures should shed light on the role of the pairing of heavy and light chains in the antigen-binding function of antibodies.
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PMID:Preliminary crystallographic study of the Fab fragments of two monoclonal anti-2-phenyloxazolone antibodies. 401 12

Suspensions of enterococci were treated with lysozyme in the presence of osmotic stabilizers. The resulting osmotically fragile bodies prepared from Streptococcus faecium strain F24 and S. faecalis strain E1 gave rise to L-forms under optimal osmotic and nutritional conditions for treatment and subsequent growth. The most critical component of the growth medium, to obtain maximum yields, was the nature and concentration of the added salt. The two most effective salts were sodium chloride and ammonium chloride in the range of 2 to 3% (w/v) added to a suitable agar base. Ammonium chloride was more versatile, because it could be used with either sucrose or polyethylene glycol 4000 as the osmotic stabilizer for preparation and dilution of the osmotically fragile bodies. Sodium chloride would not consistently support growth of S. faecium F24 as L-forms when polyethylene glycol 4000 was used as the osmotic stabilizer during lysozyme treatment. Time-course studies of concurrent cell wall removal and L-form induction suggested that maximal induction required only cell wall damage rather than complete wall removal. This method for induction of L-forms from a suspension of enterococci is a significant improvement over other presently known methods.
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PMID:Induction of enterococcal L-forms by the action of lysozyme. 499 Aug 48

A method for polyethylene glycol-induced protoplast transformation of glutamate-producing bacteria with plasmid DNA was established. Protoplasts were prepared from cells grown in the presence of penicillin by treatment with lysozyme in a hypertonic medium. The concentration of penicillin during growth affected the efficiency of formation, regeneration, and polyethylene glycol-induced DNA uptake of protoplasts. Regeneration of protoplasts was accomplished on a hypertonic agar medium containing sodium succinate and yeast extract. The spectinomycin and streptomycin resistance plasmid pCG4, originally from Corynebacterium glutamicum T250, could transform various glutamate-producing bacteria such as C. glutamicum, Corynebacterium herculis, Brevibacterium flavum, and Microbacterium ammoniaphilum. The plasmid was structurally unchanged and stably maintained in new hosts. The transformation frequency of most competent protoplasts with pCG4 DNA isolated from primary transformants was high (ca. 10(6) transformants per microgram of covalently closed circular DNA) but was still two orders of magnitude below the frequency of transfection with modified DNA of the bacteriophage phi CGI. The difference was ascribed to the involvement of regeneration in transformation.
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PMID:Protoplast transformation of glutamate-producing bacteria with plasmid DNA. 614

We have tested some assay procedures for the measurement of beta 2-microglobulin, lysozyme, alpha 1-fetoprotein and myoglobin in serum and/or urine with the use of a manual Behring laser nephelometer. The assay working ranges were: beta 2-microglobulin: 0.0038-0.038 g/L; lysozyme: 0.005-0.325 g/L. We have studied the effect of different antiserum dilution ratios and of different concentrations of polyethylene glycol 6000 on the calibration curves. The best standard curves were obtained with the use of the following antiserum dilutions: anti-beta 2-microglobulin: 1:3 with saline, 40 g/L PEG; anti-lysozyme: 1:5 with saline, 40 g/L PEG; anti alpha 1-fetoprotein: concentrated; anti-myoglobin: concentrated with added 40 g/L PEG. In the case of beta 2-microglobulin and lysozyme, laser nephelometry, could be a fast and simple procedure if a 10 times increase in sensitivity can be achieved. For the measurement of alpha 1-fetoprotein and myoglobin, the sensitivity of laser nephelometry was disappointing when compared to those reported for radioimmunoassay and enzyme immunoassay.
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PMID:Limitations of conventional laser nephelometry for the measurement of beta 2-microglobulin, lysozyme, alpha 1 fetoprotein and myoglobin in serum and urine. 617 Apr 78

Induction of a virus infection by cloned simian virus 40 DNA was chosen as a test system to detect transfer of genes from bacteria to cultured mammalian cells. Escherichia coli cells containing a recombinant plasmid with three tandem inserts of simian virus 40 DNA were able to infect CV-1 monkey cells under various conditions. The gene transfer was resistant to DNase I and therefore seems not to occur via free DNA but most likely via uptake of whole bacteria, followed by release of plasmid DNA and generation of infectious circular simian virus 40 DNA in a recombination-excision process. Spontaneous transfer was found to be infrequent, 4 x 10(9) bacteria yielding one infection per 10(7) monkey cells. The frequency was greatly increased by adding bacteria as a calcium phosphate coprecipitate or by fusion of lysozyme-treated bacteria (protoplasts) with monkey cells in the presence of polyethylene glycol. With the latter technique, 10(4) protoplasts gave rise to one infection per 15 monkey cells. Experiments with other cell lines of human, monkey, and mouse origin, and also with bacteria harboring another recombinant plasmid, indicate that DNA transfer from bacteria to mammalian cells is a general phenomenon.
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PMID:Direct transfer of cloned genes from bacteria to mammalian cells. 624 25

The fluorescence polarization of fluorescent derivatives of hemoglobin and myoglobin was measured as a function of the concentration of added polymers (PEG-6 000, PEG-20 000) and globular proteins (lysozyme, ribonuclease A, beta-lactoglobulin). The results indicated that the effective size and shape of 1-anilino-9-naphthalene sulfonate myoglobin are unaltered in the presence of up to 25 g/dl poly(ethylene glycol), whereas they are significantly altered in the presence of comparable concentrations of other proteins. The results are consistent with the hypothesis that in the presence of high concentrations of added protein, 1-anilino-9-naphthalene sulfonate myoglobin self-associates to form a dimer similar in size and shape to 1-anilino-9-naphthalene sulfonate hemoglobin.
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PMID:Evidence for protein self-association induced by excluded volume. Myoglobin in the presence of globular proteins. 627 Dec 44


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