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)

Thin sections of the cell wall of Sporosarcina ureae revealed two structurally distinct layers: a continuous amorphous zone, approximately 15 nm thick, which was adjacent to the plasma membrane, and an overlying periodic zone, approximately 16 nm thick. Sequential Triton X-100 and lysozyme treatment of isolated walls produced small fragments of the outer regular structure which allowed high-resolution, negatively stained images suitable for optical diffractometric analysis. These data suggested a tetragonal array of complex polygonal units of C-C spacing = 12 nm, with each unit joined to another by two delicate linkers. The array was entirely proteinaceous, consisting of a 150,000-dalton polypeptide which had a high affinity for Mg2+. It proved to be sensitive to chelating agents, 5 mM concentrations of Ca2+, Sr2+, or Ba2+, proteases, heat greater than or equal to 45 degrees C, sodium dodecyl sulfate, and pH greater than or equal to 5.8, but magnesium offered protection against the chelating agents and the deleterious salts.
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PMID:Surface arrays on the wall of Sporosarcina ureae. 47 3

Though DNase does not contain any cysteine residues, incubation of the enzyme with 2-nitro-5-thiocyanobenzoic acid in the presence of Ca2+ at pH values above 7.5 results in an irreversible inactivation of the enzyme. The inactivation also occurs when Ca2+ is replaced by Mg2+, but not in their absence. Amino acid analyses after acid hydrolyses of the completely inactivated ant the native enzymes show no significant differences in composition, including tryptophan and half-cystine residues. However, sodium dodecyl sulfate gel electrophoresis indicates enzyme cleavage by the treatment with 2-nitro-5-thiocyanobenzoic acid. This reagent does not inactivate chymotrypsin and lysozyme, and under conditions where bovine DNase is inactivated, does not inactivate other nucleases such as ribonuclease, snake venom phosphodiesterase, and spleen acid DNase. However, it inactivates malt DNase and can, therefore, be considered a specific inhibitor of DNase I. The inactivation kinetics is pseudo-first order, resembling Michaelis-Menten, with an affinity constant of 16.7 mM. It is the cyano group, not the thionitrobenzoic acid of 2-nitro-5-thiocyanobenzoic acid that reacts to form cyano-DNase.
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PMID:Inactivation of bovine pancreatic DNase by 2-nitro-5-thiocyanobenzoic acid. I. A novel inhibitor for DNase I. 48 54

The milk which drips from the opposite breast during breast feeding is used in some centres for feeding premature babies, yet there is little scientific information on the biology of this secretion. Drip breast milk (DBM) differs from expressed breast milk (EBM), both in its contents and in the change in its composition over the period of lactation. The fat concentration and energy value of DBM are low, compared with levels reported for EBM: protein, fat, sodium and energy value in DBM fall with the duration of lactation, whereas magnesium and calcium rise, and lactose, potassium osmolality and lysozyme remain constant. The milk fat content of DBM produced by individual donors is linearly related to the daily volume of DBM produced. Studies on 477 women admitted to the Oxford General Practice Obstetric Unit over 1 yr showed that, of the 75% who were lactating successfully 2 wk after delivery, 19% were producing DBM by 2--4 wk. Women who produced DBM did not differ in age or parity from those lactating women who did not, and their babies did not differ in birthweight, gestation, centile or sex. The suitability of DBM as a food for premature infants is discussed.
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PMID:The biology of human drip breast milk. 57 25

A single intraperitoneal injection of sodium oxalate was used to induce intrarenal tubular precipitation of calcium oxalate in rats. This experimental model was used to screen the efficacy of hydrochlorothiazide, orthophosphate, methylene blue, trypan blue, retinal folic acid, neuraminidase, and lysozyme in retarding intratubular calcium oxalate precipitation. Orthophosphate caused a 53 per cent reduction in calcium oxalate precipitation relative to the control animals.
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PMID:A survey of the effect of some drugs, chemicals, and enzymes on calcium oxalate precipitation in the rat kidney. 64 1

The effects of a highly-purified, potently bactericidal fraction from rabbit polymorphonuclear leukocytes on the envelope of Escherichia coli (W) have been examined. This leukocyte fraction has equally enriched bactericidal, permeability-increasing and phospholipase A2 activities, and is essentially devoid of lysozyme, myeloperoxidase and protease activities (Weiss, J., Franson, R.C., Beckerdite, S., Schmeidler, K. and Elsbach, P. (1975) J. Clin. Invest. 55, 33-42). Rapid killing of E. coli by this fraction is accompanied by two almost immediate alterations in the bacterial envelope: (1) a discrete increase in envelope permeability (measured by inhibition of bacterial leucine incorporation by normally impermeant actinomycin D), and, (2) hydrolysis of 14C-labeled fatty acid-prelabeled E. coli phospholipids. Both envelope effects are promptly reversed during further incubation at 37 degrees C, But not at 0 degrees C, with 40 mM Mg2+. Reversal is also produced by Ca2+ (40 mM) and trypsin (200 mug/ml), but 200 mM K+ causes only partial recovery and Na+ and hyperosmolar sucrose are ineffective. Upon addition of Mg2+, phospholipid degradation ceases abruptly and the labeled products of hydrolysis (free fatty acids and lysocompounds) disappear with a corresponding reaccumulation of radioactive diacylphosphatides. The time course of resynthesis of phospholipids coincides with that of restoration of the permeability barrier. Higher concentrations of the leukocyte fraction and prolonged incubation increase both the extent of phospholipid degradation and the time required for reversal of both envelope effects. These findings suggest that both the initiation of the increased permeability and its reversal are linked to respectively the breakdown and resynthesis of major E. coli membrane phospholipids, and thus depend on the fact that the biochemical apparatus of E. coli remains capable of biosynthesis despite loss of viability. Treatment of E. coli, exposed to the leukocyte fraction, with albumin results in extracellular sequestration of the products of hydrolysis and also restores the permeability barrier to actinomycin D, suggesting that the accumulation of lytic products of lipid hydrolysis within the bacterial envelope, rather than the loss of phospholipids per se, causes increased permeability Whereas the effects on the envelope are reversible as long as 2 h after nearly complete loss of ability to multiply by E. coli, the effect on bacterial multiplication is irreversible within 5 min.
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PMID:Reversible envelope effects during and after killing of Escherichia coli w by a highly-purified rabbit polymorpho-nuclear leukocyte fraction. 77 27

Isolated walls of Bacillus subtilis Marburg, prepared in a manner which avoided metal contamination other than by the growth medium, were incubated in dilute metal solutions, separated by membrane filtration (0.22 mum), and monitored by atomic absorption to give uptake data for 18 metals. Substantial amounts of Mg2+, Fe3+, Cu2+, Na+, and K+ (amounts which were often visible as Au3+, and Ni2+ (the higher atomic-numbered elements also visible as electron scattering), and small amounts of Hg2+, Sr2+, Pb2+, and Ag+ were taken into the wall. Some (Li+, Ba2+, Co2+, and Al3+) were not absorbed. Most metals which had atomic numbers greater than 11 and which could be detected by electron microscopy appeared to diffusely stain thin sections of the wall. Magnesium, on the other hand, partitioned into the central region, and these sections of walls resisted ruthenium red staining, which was not true for the other metals. Areas of the walls also acted as nucleation sites for the growth of microscopic elemental gold crystals when incubated in solutions of auric chloride. Retention or displacement of the metals was estimated by a "chromatographic" method using the walls cross-linked by the carbodiimide reaction to adipic hydrazide agarose beads (which did not take up metal but reduced the metal binding capacity of the walls by ca. 1%) packed in a column. When a series of 12 metal solutions was passed through the column, it became evident that Mg2+, Ca2+, Fe3+, and Ni2+ were strongly bound to the walls and could be detected by both atomic absorption and by their electron-scattering power in thin sections, qhereas the other metals were fisplaced or replaced. Partial lysozyme digestion of the walls (causing a 28% loss of a [3H]diaminopimelic acid label) greatly diminished the Mg2+ retention but not that of Ca2+, Fe3+, or Ni2+, indicating that there are select sites for various cations.
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PMID:Uptake and retention of metals by cell walls of Bacillus subtilis. 82 33

A system to study the aggregation of hydroxyapatite crystals was developed. The effect of several factors (Ca2+ x Pi product, Ca2+/Pi ratio, pH, and various substances) were tested. Pb2+, Zn2+, Mg2+ and methyleneblue had only small effects; citrate inhibited aggregation. Pyrophosphate was a strong inhibitor and the diphosphonates disodium ethane-1-hydroxy-1,1-diphosphonate and disodium dichloromethylene diphosphonate were even more potent. The monophosphonate pentanemonophosphonate had no effect. Potent inhibition also occurred with glycosaminoglycans: heparin greater than hyaluronic acid greater than dermatan sulfate greater than chondroitin 4-sulfate greater than chondroitin 6-sulfate. Urine also showed high inhibitory activity. The inhibition of heparin but not that of hyaluronic acid, PPi or urine was abolished by egg white lysozyme. The effects described might be relevant in the normal mineralization process as well as in the mechanisms leading to pathological calcification, such as urinary stone formation.
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PMID:Aggregation of hydroxyapatite crystals. 82 71

A computer search of available protein sequences and structures suggests that bacteriophage T4 lysozyme contains one region and that rabbit myosin light chains contain three regions similar, and supposedly homologous, to the calcium binding region of carp muscle calcium binding parvalbumin.
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PMID:Troponin and parvalbumin calcium binding regions predicted in myosin light chain and T4 lysozyme. 111 Oct 94

The complement component, C5a provokes the selective release of granule-associated enzymes from the intact, viable cytochalasin B-treated human polymorphonuclear leukocytes (PMN) in the absence of phagocytosis or cellular adherence to surfaces. Consquently, in this experimental system the influence of divalent cations on these two processes can be disregarded and their effects on enzymes secretion can be studied directly. Cytochalasin B-treated PMN exposed to C5a in calcium and magnesium-free media consistently secreted significant amounts of the granule-associated enzymes, beta-glucuronidase and lysozyme. The basal secretory response was not diminished if cells were preincubated with 5.0 mM EDTA, nor was it influenced if 1.0 mm or 2.0 mM EDTA were present in the reaction mixtures. The addition of calcium (up to 1.5 to 2.0 mM) produced a concentration-dependent enhancement of beta-glucuronidase release, whereas increasing amounts of calcium (above 2.0 mM) inhibited secretion of this enzyme. Lysozyme release was similarly enhanced by the addition of calcium, but inhibition with high concentrations was not observed. Calcium per se, in the absence of C5a, provoked only the release of lysozyme from these cells. The effects of calcium upon enzyme release were not associated with alterations in the state of assembly of cytoplasmic microtubules. These findings provide another example of the role of calcium in "stimulus-secretion coupling" and provide evidence that exocytosis of various granules in human PMN is regulated by independent mechanisms involving calcium.
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PMID:Influence of divalent cations upon complement-mediated enzyme release from human polymorphonuclear leukocytes. 115 Oct 72

The production of extracellular alpha-amylase and protease by protoplasts of Bacillus amyloliquefaciens has been achieved. The production of enzymically active protease was totally dependent on a high concentration of either Mg2+, Ca2+, or spermidine, but production of active alpha-amylase was not. This cation dependence of protease production was seen immediately upon addition of lysozyme to intact cells. The cations could prevent the inactivation of protease and alter the cytoplasmic membrane configuration of protoplasts. Production of active alpha-amylase and protease by protoplasts was totally inhibited by proteolytic enzymes such as trypsin, alpha-chymotrypsin, or the organism's purified extracellular protease. The evidence suggests that these degradative enzymes act specifically on the emerging polypeptide of the extracellular enzyme and that the polypeptide emerges in a conformation different from that of the native molecule.
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PMID:Evidence for extrusion of unfolded extracellular enzyme polypeptide chains through membranes of Bacillus amyloliquefaciens. 115 50


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