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)

H+ titration curves of hen egg-white lysozyme were obtained at 0.15 I in the presence of small amounts (less than 15%) of methanol, ethanol and n-propanol. The acidity constants of two groups (whose pK values in water are, respectively, 42 and 3.5) are increased in water-alcohol mixtures in comparison to water. From the evaluation of these constants as a function of alcohol concentration and hydrocarbon chain length, it is suggested that these alcohols interact specifically with lysozyme. As pK values of 4.2 and 3.5 in water are generally assigned to Asp-101 and Asp-52 respectively, it seems that interaction occurs within the active site of the enzyme.
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PMID:Hydrogen ion titration of lysozyme in alcohol-water solutions. 24 Apr 38

A conjugated shift in the levels of total acidity and lysozyme in the fasting portion of gastric juice within the system of coordinates enables the diagnosis of the stages of the adaptation syndrome and the respective levels of the functioning of the secretory gastric apparatus, which in turn specify differentiation of peptic ulcer phases. The levels of total acidity and lysozyme, the indirect parameter of the level of the secretory apparatus functioning have been measured in accordance with gastric juice fractions in healthy children.
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PMID:[Adaptive potential of the secretory system of the stomach in different phases of peptic ulcer in children]. 225 Oct 49

Alpha-Lactalbumin (alpha-LA), lysozyme, and ribonuclease are found to induce fusion of phosphatidylserine/phosphatidylethanolamine vesicles at low pH. The fusogenic behavior and the binding to phospholipid vesicles of one of these proteins, alpha-LA, are studied at a wide range of conditions. The initial rate of fusion in the presence of alpha-LA increases with increasing acidity below pH 6, and the extent of alpha-LA binding to the vesicles is also found to increase with decreasing pH. Once bound to the vesicles in acidic media, the neutralization to pH 7 fails to dislodge the alpha-LA from the vesicles, and this irreversible binding also increases with decreasing pH. A segment of alpha-LA is found to be resistant to the proteolytic digestion when initially incubated with the vesicles at low pH. The amino acid composition of this fragment was determined, and from this the sequence of alpha-LA fragment, which appears to be inserted into the bilayer, is deduced. Hydrophobic labeling with dansyl chloride renders support that this segment indeed penetrates into the hydrophobic interior of bilayer. Since both the N-terminal and the C-terminal of this vesicle-bound protein are accessible to the externally added proteolytic enzymes, it is concluded that a loop of the polypeptide segment goes into the bilayer. These observations, taken together, suggest a possibility that the penetration by a loop of alpha-LA segment into the phospholipid bilayer is responsible for the fusion.
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PMID:Fusion of phospholipid vesicles induced by alpha-lactalbumin at acidic pH. 302 64

Extraction of phospholipids from stationary phase grown cells of the Gram+ bacteria, Bacillus megaterium, Bacillus subtilis, Bacillus cereus and Micrococcus lysodeikticus was found to be incomplete with various commonly used extraction procedures. Phosphatidylglycerol and phosphatidylethanolamine were readily extracted but up to 95% of the cardiolipin appeared to be retained within the cell residue. Extraction of the cardiolipin could be slightly enhanced by increasing the temperature or the acidity of the extraction solutions but complete extraction was obtained only after lysozyme treatment of intact cells or cell residues remaining after extraction. In addition complete extraction could be observed in the case of cells harvested in the early logarithmic phase. Freeze-fracture electron microscopy was carried out on the cell residue remaining after extraction of all phospholipids except cardiolipin. A fracture plane through the plasma membrane could not be observed anymore. Instead fracture planes through lipid vesicles were observed. These vesicles reside within the remnants of the cytoplasm and consist most likely of the non-extracted cardiolipin.
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PMID:Cardiolipin, a major phospholipid of Gram-positive bacteria that is not readily extractable. 677 94

Lysozyme concentration in the gastric juice of 34 patients with peptic ulcer and 10 practically healthy persons was studied. In the patients with peptic ulcer the lysozyme levels in the gastric juice were found to be lower. A significant decrease in the lysozyme concentration was observed in the patients suffering from peptic ulcer for more than 2 years. During the first months of the disease increased levels of lysozyme were recorded. Relationship between the lysozyme concentration in the gastric juice and the acidity of the gastric contents was shown. Decreased concentrations of lysozyme were more pronounced in the patients with increased levels of hydrochloric acid.
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PMID:[Lysozyme concentration in the gastric juice in peptic ulcer]. 735 1

The adsorption of proteins with net positive charges (pI > pH) on the walls of fused-silica capillaries is a common problem in the analysis of proteins by capillary electrophoresis. This paper explores the use of polycationic polymers as noncovalent coatings to limit this problem. The behavior of three sets of proteins was compared using uncoated and coated capillaries: (i) a protein charge ladder obtained by acetylation of lysozyme (EC 3.2.1.17); (ii) a protein charge ladder obtained by acetylation of carbonic anhydrase II (EC 4.2.1.1); (iii) a test panel of proteins with a range of values of molecular weight and pI. Four polycationic polymers were examined: polyethylenimine (PEI; MWav = 15000), Polybrene (MWav = 25000), poly(methoxyethoxyethyl)ethylenimine (MWav = 64000), and poly(diallyldimethylammonium chloride) (MWav = 10000). Detection of proteins with high pI was readily achieved using the first three of these polycationic polymer coatings but not with the poly(diallyldimethyl-ammonium chloride). Examination of the stability of these coatings indicates that they are robust: the change in electroosmotic flow was less than 10% for 25 replications of the same separations, using capillaries coated with PEI or Polybrene. This study demonstrates that the charge ladder obtained by acetylation of lysozyme is a good model with which to test the efficiency of polycationic coatings. A study of the electrophoretic mobilities of the members of this charge ladder at pH 8.3 determined the effective charge of lysozyme (Zp(0) = +7.6 +/- 0.1) and established the acidity of the alpha-ammonium group of lysozyme (pKa = 7.8 +/- 0.1). Results from the test panel of proteins suggest that protein adsorption is mainly driven by electrostatic interactions.
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PMID:Noncovalent polycationic coatings for capillaries in capillary electrophoresis of proteins. 910 78

The capability to enhance or suppress the nucleation of protein crystals opens opportunities in various fundamental and applied areas, including protein crystallography, production of protein crystalline pharmaceuticals, protein separation, and treatment of protein condensation diseases. Herein, we show that the rate of homogeneous nucleation of lysozyme crystals passes through a maximum in the vicinity of the liquid-liquid phase boundary hidden below the liquidus (solubility) line in the phase diagram of the protein solution. We found that glycerol and polyethylene glycol (which do not specifically bind to proteins) shift this phase boundary and significantly suppress or enhance the crystal nucleation rates, although no simple correlation exists between the action of polyethylene glycol on the phase diagram and the nucleation kinetics. The control mechanism does not require changes in the protein concentration, acidity, and ionicity of the solution. The effects of the two additives on the phase diagram strongly depend on their concentration, which provides opportunities for further tuning of nucleation rates.
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PMID:Control of protein crystal nucleation around the metastable liquid-liquid phase boundary. 1082 98

We have studied the one-electron reduction of oxidized Chlamydomonas reinhardtii thioredoxin and compared it to that of hen egg white lysozyme, using CO(2)(*) (-) free radicals as reductants. This comparison shows that the thioredoxin disulfide/thiol redox couple has different properties than that of lysozyme: the disulfide radical pK(a) is much lower (around 5 for small disulfides, 4.62 for lysozyme, <3 for thioredoxin). To get a better understanding of the modulation of the thioredoxin redox properties we have constructed the mutants W35A and D30A. Their reduction by pulse radiolysis indicates that W35 strongly controls both the disulfide radical acidity (the pK(a) in W35A is equal to ca. 4), and the thiol reactivity. Asp30 is also involved in the control of proton transfer to the disulfide free radical. In addition, its removal seems to increase the reduction potential of the thioredoxin thiyl/thiol couple. Overall, the reduction properties of thioredoxin confirm its nature as a unique reductant.
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PMID:Redox properties of protein disulfide bond in oxidized thioredoxin and lysozyme: a pulse radiolysis study. 1092 22

A complex of biological characteristics important for design of the therapeutic and prophylactic activities of Bifidobacterium and Lactobacillus preparations made with the use of hydrolysate-milk and hydrolysate-soybean media was comparatively estimated. The use of the hydrolysate-soybean medium resulted in an increase of the antagonistic activity of the preparations against a number of opportunistic pathogens that was not connected with changing of their acidity and the content of lysozyme, a bacteriolytic enzyme in the culture fluid. The change in the cultivation conditions due to substitution of the hydrolysate-milk medium for the hydrolysate-soybean medium stimulated the adhesive capacity of the production strains used in the study, which was especially evident with respect to the representatives of the genus Bifidobacterium.
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PMID:[Biological characterization of Bifidobacterium and Lactobacillus preparations made with the use of hydrolysate-milk and hydrolysate-soybean media]. 1572 43

The active site of lysostaphin is shown to contain a residue of glutamic acid. As judged by a pK value of 9.2 (with pentaglycine bridges in peptidoglycan of staphylococci as a substrate), another ionogenic residue could be the epsilon-amino group of a lysine. However, the pH value near a negatively charged cell is supposed to be strongly shifted to acidity as compared to the pH of the solution volume. This shifts the enzyme pH dependence curve in solution to alkalinity. Therefore, the other group might be histidine, which is consistent with the X-ray crystallographic data. A similar shift is likely to occur for lysozyme in the case of Micrococcus lysodeikticus cells. Determination of pK of ionogenic groups in the active sites of alkaline enzymes responsible for lysis of negatively charged bacterial cells gives their apparent values because the "pericellular" and "voluminous" values of pH are not coincident.
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PMID:Ionogenic groups in the active site of lysostaphin. Kinetic and thermodynamic data compared with x-ray crystallographic data. 1792 58


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