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:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lysozyme-treated cells of a blue-green alga, Plectonema boryanum, had an internal pH of 7.3+/-0.2 under isotonic and hypotonic conditions. This value was similar to that of untreated cells. The CCCP-induced biphasic H+ change seen in the isotonic cells was not observed in the hypotonically treated cells. The biphasic time course remained in the hypotonic preparation if CaCl2 or MgCl2 was added prior to the osmotic shock. It is suggested that the cells have two compartments of H+ concentration. The outer region may be more acidic than the inner region. A light-induced H+ efflux was observed under isotonic conditions and an influx of H+ under hypotonic conditions. The H+ influx was not observed when lysozyme-treated cells were incubated with CaCl2 or MgCl2 prior to the hypotonic treatment. Two types of effects of divalent cations, one on the rigidity of the outer membrane and another on the permeability characteristics of the inner photosynthetic membrane, are indicated. Rearrangement of the photosynthetic membranes and an apparent inversion of the H+ pump by hypotonic shock are also suggested.
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PMID:H+ translocation in lysozyme-treated cells of the blue-green alga Plectonema boryanum. Difference between isotonically and hypotonically treated preparations and effects of divalent cations. 2 Nov 72

The restricted access of lysozyme to the murein layer of exponential phase Escherichia coli is enhanced considerably by osmotic shock. When cells suspended in Tris/EDTA/sucrose are diluted 11-fold in water or 10 mM EDTA in the presence of lysozyme, their susceptibility to lysozyme increases by a factor of 50--100, for both Escherichia coli JC411 and W3110, grown to the early exponential phase in unsuppleneted or supplemented minimal media, and in Brain Heart Infusion. Since an 11-fold dilution causes lysis of lysozyme spheroplasts, the effects of a 2-fold dilution have also been investigated. A 2-fold dilution of cell suspended in TrisEDTA/sucrose still increases their susceptibility to lysozyme by a factor of 10--50, but the resulting spheroplasts remain intact. EDTA is necessary to permit lysozyme access to the murein layer during the dilution, which is ineffective in the presence of 5 mM MgCl2. These results are discussed in terms of the formation of lysozyme spheroplasts from young Escherichia coli.
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PMID:The effect of osmotic shock on the accessibility of the murein layer of exponentially growing Escherichia coli to lysozyme. 34 63

The outer and inner cytoplasmic membranes of Pseudomonas aeruginosa were separated as small and large membranes, respectively, from the cell envelope of this organism treated with lysozyme in Tris-chloride buffer containing sucrose and MgCl2 by differential centrifugation. The small membrane fraction contained predominantly 2-keto-3-deoxyoctonate (KDO), and little cytochromes or oxidase activities. The small membrane was composed of only 9 polypeptides and showed homogeneous small vesicles electron-microscopically. On the other hand, the large membrane fraction had high cytochrome contents and oxidase activities, and little KDO. The large membrane was composed of a number of polypeptides and showed large fragments or vesicles electron-microscopically. These results indicate that the small and large membranes are the outer and inner cytoplasmic membranes of P. aeruginosa, respectively. The isolated outer membrane showed a symmetrical protein peak with a density of 1.23 on sucrose density gradient centrifugation and the isolated inner membrane showed an unusually high density, probably due to association with ribosomes and extrinsic or loosely bound proteins. EDTA lowered the density of both membranes and caused lethal damage to the outer membrane, causing disintegration with the release of lipopolysaccharide (LPS), proteins and phospholipid.
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PMID:Isolation and characterization of outer and inner membranes from Pseudomonas aeruginosa and effect of EDTA on the membranes. 41 55

Protoplasts of Streptomyces hygroscopicus 155 producing nigericin, a polyether antibiotic, were prepared. Conditions for protoplasting and optimal concentrations of lysozyme and glycine, and the age of mycelium were studied. With the method of the experiment design, concentrations of four components: CaCl2, MgCl2, KH2PO4 and TES buffer in the regeneration medium were determined. The levels of CaCl2 and TES buffer proved to be the most important parameters.
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PMID:[Preparation and regeneration of protoplasts of the strain Streptomyces hygroscopicus 155]. 130 22

1. The behaviour of the miracidium of Schistosoma mansoni after contact with agar blocks containing Biomphalaria glabrata snail conditioned water (SCW) or its components, was studied. 2. "Repeated investigation" was the most specific response at contact with the snail host. 3. Fractionation and specific chemical treatment of SCW revealed that this response was stimulated by a lysozyme sensitive glycoconjugate with a mol. wt greater than 300,000. 4. Low molecular weight components of SCW had no stimulatory effect on the miracidia, although MgCl2 offered as pure chemical did so.
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PMID:Miracidium of Schistosoma mansoni: a macromolecular glycoconjugate as signal for the behaviour after contact with the snail host. 134 64

Phospholipase C from rat liver with a molecular weight of 87,000 (PLC delta) is stimulated by polyamines, basic proteins, and basic polyamino acids. The activation occurs in both the presence and the absence of detergents. Half-maximum activation by spermine is observed at 0.15 mM, with optimum effects between 0.2 and 0.5 mM. Spermine inhibits above 0.5 mM. Half-maximum activation by spermidine and putrescine is observed at 0.9 and 6 mM, respectively, with optimum effects at 2 and 5 mM, respectively. These polyamines also inhibit at higher concentrations. Neomycin activates the enzyme with an optimum concentration of 10 microM, but maximum activation is less than with polyamines. Half-maximum activation by histone 2B occurs at 0.5 micrograms/ml (36 nM), with maximum stimulation at 1.5 micrograms/ml. Other histones, protamine, melittin, poly-L-ornithine, poly-L-lysine, poly-D-lysine, and poly-L-arginine, activate optimally at 3-10 micrograms/ml. Myelin basic protein and lysozyme activate optimally at 50-100 micrograms/ml. Typical activations are three- to eightfold, but under some conditions the enzyme shows little or no activity in the absence of basic activators. The basic activators lower the salt concentration required for maximal activity. In the case of the detergent-micelle assay, histone shifts the optimum NaCl concentration from 350 to 200 mM for PIP2, from 260 to 100 mM for PIP, and from 150 to 0 mM for PI. Histone potentiates the activation by Ca2+, but does not shift the optimum Ca2+ concentration. The optimum salt and Ca2+ concentrations are linked, such that a decrease in the concentration of one decreases the optimum concentration of the other. Activation by histone is diminished by MgCl2 in a concentration-dependent manner.
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PMID:Activation of phosphoinositide-specific phospholipase C delta from rat liver by polyamines and basic proteins. 165 25

PTPA, a specific phosphotyrosyl phosphatase activator of the PCSH2 and PCSL protein phosphatases, was purified up to apparent homogeneity from Xenopus laevis ovaries and rabbit skeletal muscle and highly purified from dog liver. PTPA appears as a 40-kDa protein in gel filtration, as well as in sucrose gradient centrifugation, and as a 37-39-kDa protein doublet in SDS-PAGE. Its estimated cellular concentration of 0.75 microM in oocytes or 0.25 microM in rabbit skeletal muscle is suggestive of an important role in the regulation of the cellular PTPase activity. The PTPase activation reaction of the PCSL phosphatase is time-dependent, ATP and Mg2+ being essential cofactors [A50(ATP) = 0.12 mM in the presence of 5 mM MgCl2]. With RCM lysozyme as substrate, the specific activity of the PTPA-activated PCSL phosphatase is 700 nmol of Pi/(min.mg). The pH optimum of the PTPase shifts from 8.5-9 in basal conditions to a neutral pH (7-7.5), and the A50 for the essential metal ion Mg2+ is decreased (3 mM). The activation is rapidly reversed in the presence of the substrate, and more slowly after removal of ATP.Mg. The PTPA-activated PCSL phosphatase represents a major PTPase activity in the cytosol of X. laevis oocytes (at least 50% of the measurable PTPase with RCM lysozyme phosphorylated on tyrosyl residues). The PTPA activation is specific for the PTPase activity of the PCSL and PCSH2 phosphatases, without affecting their phosphoseryl/threonyl phosphatase activity. However, effectors of the phosphorylase phosphatase activity, such as polycations and okadaic acid, also influence the PTPase activity. Phosphorylase alpha inhibits the activated PTPase activity (I50 = 5 microM). The PTPase activity of the other oligomeric PCS phosphatases (PCSH1 and PCSM) is not influenced, suggesting an inhibitory role for some of their subunits. This activation is compared with the recently described PTPase stimulation of the PCS phosphatases by ATP/PPi [Goris, J., Pallen, C. J., Parker, P. J., Hermann, J., Waterfield, M. D., & Merlevede, W. (1988) Biochem. J. 256, 1029-1034] and by tubulin [Jessus, C., Goris, J., Cayla, X., Hermann, J., Hendrix, P., Ozon, R., & Merlevede, W. (1989) Eur. J. Biochem. 180, 15-22].
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PMID:Isolation and characterization of a tyrosyl phosphatase activator from rabbit skeletal muscle and Xenopus laevis oocytes. 215 85

The correlation between protein solubility and the preferential interactions of proteins with solvent components was critically examined with aqueous MgCl2 as the solvent system. Preferential interaction and solubility measurements with three proteins, beta-lactoglobulin, bovine serum albumin, and lysozyme, resulted in similar patterns of interaction. At acid pH (pH 2-3) and lower salt concentrations (less than 2 M), the proteins were preferentially hydrated, while at higher salt concentrations, the interaction was either that of preferential salt binding or low salt exclusion. At pH 4.5-5, all three proteins exhibited either very low preferential hydration or preferential binding of MgCl2. These results were analyzed in terms of the balance between salt binding and salt exclusion attributed to the increase in the surface tension of water by salts, which is invariant with conditions. It was shown that the increase in salt binding at high salt concentration is a reflection of mass action, while its decrease at acid pH is due to the electrostatic repulsion between Mg2+ ions and the high net positive charge on the protein. The preferential interaction pattern was paralleled by the variation of protein solubility with solvent conditions. Calculation of the transfer free energies from water to the salt solutions for proteins in solution and in the precipitate showed dependencies on salt concentration. This indicates that the nature of interactions between proteins and solvent components is the same in solution and in the solid state, which implies no change in protein structure during precipitation. Analysis of the transfer free energies and preferential interaction parameter in terms of the salting-in, salting-out, and weak ion binding contributions has led to the conclusions that, when the weak ion binding contribution is small, the predominant protein-salt interaction must be that of preferential salt exclusion most probably caused by the increase of the surface tension of water by addition of the salt. A necessary consequence of this is salting-out of the protein, if the protein structure is to remain unaltered.
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PMID:Preferential interactions determine protein solubility in three-component solutions: the MgCl2 system. 233 71

The observed preferential hydration of proteins in aqueous MgCl2 solutions at low pH and low salt concentration (Arakawa et al., 1990) prompted a scrutiny of possible protein stabilization by MgCl2 under the same conditions, in view of earlier observations in aqueous solutions of sugars, amino acids, and a number of salts that preferential hydration is usually accompanied by the stabilization of the native structure of globular proteins. The results of thermal transition experiments on five proteins (ribonuclease A, lysozyme, beta-lactoglobulin, chymotrypsinogen, and bovine serum albumin) revealed neither significant stabilization nor destabilization of the protein structures by MgCl2 both at acid conditions (except for ribonuclease A, which was stabilized, but to a much smaller extent than by MgSO4) and at higher pH at which MgCl2 displayed little preferential hydration. This was in contrast to the great stabilizing action of MgSO4 at the same conditions. 2-Methyl-2,4-pentanediol (MPD), which gives a very large preferential hydration of native ribonuclease A at pH 5.8 [Pittz & Timasheff (1978) Biochemistry 17, 615-623], was found to be a strong destabilizer of that protein at the same conditions. Analysis of the preferentially hydrating solvent systems led to their classification into two categories: those in which the preferential hydration is independent of solution conditions and those in which it varies with conditions. The first always stabilize protein structure, while the second do not. In the first category the predominant interaction is that of cosolvent exclusion, determined by solvent properties, with the protein being essentially inert. In the second category interactions are determined to a major extent by the chemical nature of the protein surface.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Why preferential hydration does not always stabilize the native structure of globular proteins. 233 72

The specificity of the basic bactericidal/permeability increasing protein (BPI) of polymorphonuclear leukocytes (PMN) for gram-negative bacteria is attributable to its strong attraction for the negatively charged envelope LPS. The antibacterial activity of PMN homogenates or extracts toward Escherichia coli corresponds to their BPI content and is blocked by anti-BPI IgG, suggesting that BPI action is unaffected by the presence of other PMN proteins. To test if BPI is preferentially bound to E. coli when other antibacterial proteins are present, we have measured binding in buffered (pH 7.5) balanced salts solution of [125I] human BPI to E. coli J5 in the presence and absence of other human PMN granule proteins. BPI binding is saturable with an apparent K = 23 nM and 2.2 million binding sites/cell. While binding of [125I] human BPI is competitively inhibited by human or rabbit BPI, it is only weakly inhibited by myeloperoxidase, lysozyme, or cathepsin G. In contrast, myeloperoxidase binding to E. coli is strongly inhibited by BPI. Moreover, incubation of E. coli with crude extracts of PMN or CML spleen results in near quantitative binding of BPI, identified by silver staining and immunoblotting after SDS-PAGE of the washed E. coli pellet, without recognizable binding of other leukocyte proteins (greater than 98% of added total protein is recovered in supernatant). After addition of 200 mM MgCl2, approximately 80% of bound BPI is released as fully active and pure protein (as judged by SDS-PAGE and HPLC). Thus the selective and reversible binding of BPI in crude PMN extracts to target bacteria provides a one-step "affinity" purification procedure.
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PMID:Preferential binding of the neutrophil cytoplasmic granule-derived bactericidal/permeability increasing protein to target bacteria. Implications and use as a means of purification. 253 11


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