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

---

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

1. A cell-free preparation of membrane fragments was prepared from the thermophilic blue-green alga Phormidium laminosum by lysozyme treatment of the cells followed by osmotic shock to lyse the spheroplasts. The membrane fragments showed high rates of photosynthetic electron transport and O2 evolution (180-250 mumol of O2/h per mg of chlorophyll a with 2,6-dimethyl-1,4-benzoquinone as electron acceptor). O2-evolution activity was stable provided that cations (e.g. 10mM-Mg2+ or 100mM-Na+) or glycerol (25%, v/v) were present in the suspending medium. 2. The components of the electron-transport chain in P. laminosum were similar to those of other blue-green algae: the cells contained Pigment P700, plastocyanin, soluble high-potential cytochrome c-553, soluble low-potential cytochrome c-54 and membrane-bound cytochromes f, b-563 and b-559 (both low- and high-potential forms). The amounts and midpoint potentials of the membrane-bound cytochromes were similar to those in higher-plant chloroplasts. 3. Although O2 evolution in P. laminosum spheroplasts was resistant to high temperatures, thermal stability was not retained in the cell-free preparation. However, in contrast with higher plants, O2 evolution in P. laminosum membrane fragments was remarkably resistant to the non-ionic detergent Triton X-100.
...
PMID:Photosynthetic electron transport in a cell-free preparation from the thermophilic blue-green alga Phormidium laminosum. 677 63

The alkaline phosphatase of Plectonema boryanum shows a considerable increase in activity following placement of the cells in a phosphate free medium. Five days of phosphate starvation result in a 14-fold increase of alkaline phosphatase activity. Growth in the presence of inhibitors of transcription and translation indicate that the synthesis of the enzyme is de novo. Orthophosphate causes an immediate inhibition of enzyme activity. Enzyme was extracted from P. boryanum with lysozyme or polymyxin B treatment in order to make comparative studies of cell bound and cell free enzyme. Of several enzyme specific inhibitors tested, mercuric chloride was the most effective. Temperature studies showed that the cell bound enzyme was most active at 40 degrees C while the cell free enzyme was most active at 70 degrees C. The pH optimum was 9 for the cell free enzyme, and 8.8 for the cell bound. The enzyme was tested to determine if it could hydrolyse a number of different organic compounds. It hydrolysed p-nitrophenol phosphate 100%, fructose-6-phosphate 45%, beta-glycerol phosphate 25% and other compounds to a lesser degree. Of seventeen other Cyanobacteria tested for alkaline phosphatase, all were positive, and of these eleven were inducible for the enzyme. Ten of the isolates released some of the enzyme into the culture medium. Michaelis constants for the enzyme were also determined.
...
PMID:Physiological aspects of alkaline phosphatase in selected cyanobacteria. 679 13

The effect of four osmotic stabilizers on the radiometric detection of osmotically sensitive populations of E. coli, S. typhimurium, and E. cloacae was studied. The addition of sucrose, sorbitol, glycerol, or ethylene glycoll to BACTEC 6B blood culture medium failed to improve the sensitivity of the system and produced an inhibitory effect on the level of 14CO2 released by organisms previously exposed to lysozyme and ECTA or to penicillin followed by the lysozyme treatment. The same effect was observed both in blood free media and simulated blood cultures. The addition of proline to sucrose-containing hypertonic media had no effect on growth index readings.
...
PMID:The effect of osmotic stabilizers on the radiometric detection of osmotically sensitive populations of some gram-negative bacteria. 680 67

The HF treatment of teichoic acid-glycopeptide complexes isolated from lysozyme digests of Bacillus coagulans AHU 1366 cell walls gave a disaccharide, glucosyl beta (1 leads to 4)N-acetylglucosamine, along with dephosphorylated repeating units of the teichoic acid chain, galactosyl alpha (1 leads to 2) glycerol. Mild alkali treatment of the complexes yielded the disaccharide linked to glycopeptide, whereas direct heating of the cell walls at pH 2.5 yielded the same disaccharide linked to teichoic acid. The Smith degradation of the complexes revealed that the galactose residue is a component of backbone chain. Thus it is concluded that this disaccharide is involved in the linkage region between poly(galactosylglycerol phosphate) and peptidoglycan in cell walls. Membrane-catalyzed synthesis of this disaccharide on a lipid followed by transfer of glycerol phosphate from CDP-glycerol to the disaccharide-linked lipid in the absence or in the presence of UDP-galactose also supports this conclusion.
...
PMID:Structural and biosynthetic studies on linkage region between poly(galactosylglycerol phosphate) and peptidoglycan in Bacillus coagulans. 683 May 96

The phosphoglycerate transport system was employed to supply energy-depleted, lysozyme-treated Salmonella typhimurium cells with a continuous intracellular source of phosphoenolpyruvate. When the cells had been induced to high levels of the phosphoglycerate transport system, a low extracellular concentration of phosphoenolpyruvate (0.1 mM) half maximally stimulated uptake of methyl alpha-glucoside via the phosphoenolpyruvate:sugar phosphotransferase system. If the phosphoglycerate transport system was not induced before energy depletion, 100 times this concentration of phosphoenolpyruvate was required for half-maximal stimulation. Phosphoenolpyruvate could not be replaced by other energy sources if potassium fluoride (an inhibitor of enolase) was present. Inhibition of [14C]-glycerol uptake into energy-depleted cells by methyl alpha-glucoside was demonstrated. A concentration of phosphoenolpyruvate which stimulated methyl alpha-glucoside accumulation counteracted the inhibitory effect of the glucoside. In the presence of potassium fluoride, phosphoenolpyruvate could not be replaced by other energy sources. Inhibition of glycerol uptake by methyl alpha-glucoside in intact untreated cells was also counteracted by phosphoenolpyruvate, but several energy sources were equally effective; potassium fluoride was without effect. These and other results were interpreted in terms of a mechanism in which the relative proportions of the phosphorylated and nonphosphorylated forms of a cell constituent influence the activity of the glycerol transport system.
...
PMID:Regulation of carbohydrate transport activities in Salmonella typhimurium: use of the phosphoglycerate transport system to energize solute uptake. 698 88

In order to clarify the mechanism of polyol-induced stabilization of protein, the thermal denaturation of lysozyme was studied at pH 4 in aqueous mixtures of some polyols (ethylene glycol, glycerol, erythritol, xylitol, and sorbitol) by a differential scanning calorimetry (DSC). The denaturation temperature, Td, increased with increasing the polyol concentration and the number of hydroxymethyl groups per polyol molecule. The calorimetric enthalpy or denaturation, delta H cal, increased with the increase in polyol concentration, but it was not significantly affected by the chain length of the polyol: delta H cal was about 30 kcal/mol larger in 30% (w/w) aqueous polyols than in water. The standard thermodynamic parameters for denaturation, delta G degrees, delta S degrees, and delta H degrees, which were calculated for glycerol and sorbitol systems using Td and delta H cal and assuming a constant heat capacity change, were an increasing function of polyol concentration. According to the thermodynamics of three component systems, it appeared that one or two polyol molecules are preferentially excluded from the domain of this protein on thermal denaturation. These thermodynamic data support the hypothesis that the thermal stabilization of lysozyme by polyols is due to a preferential solvent interaction effect which strengthens the hydrophobic interaction of the protein.
...
PMID:Calorimetric study on thermal denaturation of lysozyme in polyol-water mixtures. 709 84

The endothermic thermal transitions (i.e., denaturation) of lyophilized recombinant bovine somatotropin (rbSt) and lysozyme as seen via differential scanning calorimetry were evaluated with respect to moisture and excipients. The denaturation temperature, Tm, of rbSt and lysozyme decreased with increasing moisture irrespective of the excipient. However, the magnitude of the decrease elicited by moisture was dependent on the type of excipient. Furthermore, the effect of the excipient was dependent on the moisture content; excipients decreased Tm in low moisture solids (i.e., < 5% moisture) and increased it in hydrated solids (i.e., > 15% moisture). In the dry state (< 1% moisture), the addition of 50% sucrose, sorbitol, or glycerol lowered the Tm of rbSt from 161 degrees C to 136, 120, and 83 degrees C, respectively, indicating a destabilizing mechanism. Likewise, the Tm of lysozyme decreased from 156 degrees C to 142, 128, and 97 degrees C due to the addition of sucrose, sorbitol, and glycerol, respectively. At higher moisture contents, the excipients promoted a higher transition temperature at a given moisture content than the pure protein systems, indicating a stabilizing mechanism. An increase in the enthalpy of unfolding for dehydrated lysozyme was noted with increasing levels of moisture and/or excipient, despite the observed decrease in Tm. The thermal stability, or Tm, of the dehydrated proteins appeared to be correlated to the glass transition temperature (Tg) of the excipient, which in turn should be related to the Tg of the system. The lower the Tg of the excipient, the greater was the degree of destabilization.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Thermally induced denaturation of lyophilized bovine somatotropin and lysozyme as impacted by moisture and excipients. 756 8

The mechanism of irreversible inactivation of lysozyme at neutral pH at 100 degrees C, and effects of additives on the inactivation were investigated. The thermoinactivation of lysozyme at neutral pH was caused by intra- and intermolecular disulfide exchange and the production of irreversibly denatured lysozyme, which was destabilized by multiple chemical reactions other than disulfide exchange. In addition, independently, deamidation slightly affected the inactivation by causing a decrease of electrostatic interaction between positive charges of lysozyme and negative charges of the bacterial cell wall. As for the effects of additives on the inactivation, a small amount of copper ion suppressed intra- and intermolecular disulfide exchange by catalyzing air oxidation of heat-induced trace amounts of free thiols, and organic reagents (acetamide, ethanol, and glycerol) changed the mechanism of the inactivation to that under acidic conditions by shifting the pKa values of dissociable residues and also suppressed intermolecular disulfide exchange by decreasing hydrophobic interactions.
...
PMID:Effects of additives on irreversible inactivation of lysozyme at neutral pH and 100 degrees C. 760 27

Effects of 10-30% (v/v) of dimethyl sulfoxide, glycerol, and ethylene glycol on the H-O-H bending vibration of water and the amide I bands of horse heart cytochrome c and chicken egg white lysozyme in 25 mM sodium phosphate buffer (pH 7.4) were examined at 20 degrees C by Fourier transform infrared spectroscopy. The H-O-H bending mode of water was strongly affected by these cryoprotectant solvents. Increasing the concentration of cryosolvents from 0 to 30% shifts the water bending band maximum from 1645 to about 1650 cm-1. Second-derivative analysis reveals significant changes in conformation-sensitive amide I regions of lysozyme ascribed to alpha-helix (1657 cm-1), turn (1674 cm-1), and unordered (1646 cm-1) structures; each cryosolvent increases the intensity of the 1657 cm-1 band at the expense of bands at 1674 and 1646 cm-1. No changes in spectra deemed significant were observed for cytochrome c under the same conditions. There is no spectral evidence of structural randomization of proteins due to the presence of these cryosolvents. Cryosolvent-induced changes in secondary structure of proteins may result from changes in water structure which, in turn, perturb the structure of the protein and/or from direct interactions between cryosolvent and protein.
...
PMID:Effects of dimethyl sulfoxide, glycerol, and ethylene glycol on secondary structures of cytochrome c and lysozyme as observed by infrared spectroscopy. 762 25

The temperature dependence of the efficiency of oxidative refolding was examined for hen lysozyme three-disulfide derivatives produced in Escherichia coli. Each derivative was designed to lack one of the four disulfide bridges in authentic lysozyme: delta 1 (Cys6-->Ser, Cys127-->Ser), delta 2 (Cys30-->Ser, Cys115-->Ser), delta 3 (Cys64-->Ser, Cys80-->Ser), delta 4 (Cys76-->Ser, Cys94-->Ser), delta 2Ala (Cys30-->Ala, Cys115-->Ala), and delta 4Ala (Cys76-->Ala, Cys94-->Ala). The optimal refolding temperature was lowest for delta 1 (19 degrees C) and highest for delta 4Ala (30 degrees C). The chromatographically purified, completely refolded three-disulfide species were not stable above the optimal refolding temperature in the presence of glutathione. The stability of each of them was determined from the far-UV CD thermal denaturation measurement at pH 3.9 in the absence of glutathione, where the denaturation was reversible. The transition temperature was lowest for delta 1 and highest for delta 4Ala. Precise values of difference in the transition temperature among the three-disulfide derivatives were found to correlate with those in the optimal refolding temperature. Next, the effect of glycerol, which has been shown to increase the refolding efficiency [Sawano et al. (1992) FEBS Lett. 303, 11-14], was examined for delta 1 in detail. The optimal temperature for refolding increased by 3-4 degrees C with the increase in glycerol concentration by 10%. The amount of increase in the optimal refolding temperature was nearly equal to the amount of the increase in thermal stability in the presence of glycerol of refolded and purified delta 1.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Relationship between the optimal temperature for oxidative refolding and the thermal stability of refolded state of hen lysozyme three-disulfide derivatives. 799 58


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---