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)

Postnuclear supernates from homogenates of purified neutrophil polymorphonuclear leukocytes (PMNs) from human blood were fractionated by zonal sedimentation and isopycnic equilibration in sucrose gradients. The fractions were characterized biochemically by measuring protein content and the activities of eight enzymes. Selected fractions were further analyzed by electron microscopy. In both centrifugation systems, azurophil and specific granules could be resolved almost completely. Azurophil granules sediment three to four times faster than the specifics and have an average density of 1.23. They contain all the peroxidase of the cells, large portions of four lysosomal hydrolases, and about half of the total lysozyme, and therefore appear to be, in biochemical terms, very similar to the azurophil granules of rabbit PMNs. The specific granules, which have an average density of 1.19, contain the remaining half of the lysozyme but appear to be free of the other components of the azurophil granules, and of alkaline phosphatase. Isopycnic equilibration disclosed a minor lysosomal population, which strongly overlaps the specific granules, and made possible the identification of a membrane-fraction which is characterized by the presence of the thiol-sensitive acid 4-nitrophenyl phosphatase and of alkaline phosphatase.
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PMID:Biochemical and morphological characterization of azurophil and specific granules of human neutrophilic polymorphonuclear leukocytes. 437 Oct 42

Human blood neutrophilic leukocytes were separated and purified by modifications of the Hypaque/Ficoll and dextran separation methods, resulting in a suspension which was greater than 96% neutrophils. Neutrophils were prepared in 0.34 M sucrose containing heparin and were clarified of nongranular debris by sequential passage through polycarbonate filters of pore size 5 mu and 2 mu. Isopycnic sucrose gradients of such filtrates revealed three major bands. The gradient separated fractions were studied by electron microscopy including peroxidase cytochemistry and by enzyme assay for myeloperoxidase (MPO), beta-glucuronidase, muramidase alkaline phosphatase and acid phosphatase utilizing both p-nitrophenylphosphate (pnp) and beta-glycerophosphate as substrates. Peroxidase-positive granules were observed at both density 1.22 (band A) and density 1.20 (band B). Three peroxidase-negative granules were identified: the round or oval peroxidase-negative granule of density 1.22 (band A) and two smaller granules, distinguishable by size and shape at density 1.18 (band C). Band C granules contain crystalloid inclusions. Peaks of muramidase activity coincided with bands A and C, suggesting the presence of muramidase in the peroxidase-negative granules of density 1.22 and in one or both of the peroxidase-negative granules at density 1.18. beta-Glucuronidase was distributed like MPO, with a major peak in band B and a minor peak in band A. Acid beta-glycerophosphatase was largely in band A. Acid pnp phosphatase was nonspecifically associated with soluble nongranular protein which always remained at the origin of sucrose gradients. Alkaline phosphatase was not granule associated and sedimented alone to density 1.145, which is highly suggestive of a cytoplasmic membrane localization for this enzyme.
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PMID:Separation and characterization of human neutrophil granules. 444 23

In human leukemic myeloblasts, the granule enzymes beta-glucuronidase, myeloperoxidase and acid phosphatase were associated with light particles of varying densities that were separable from each other by means of zonal density gradient centrifugation. In more mature granulocytic cells of chronic myelogenous leukemia the three enzymes merged within a single group of denser particles; such particles were absent in myeloblasts. Myeloblast particles had two to three times higher activity of beta-glucuronidase and acid phosphatase, but only one-tenth of the myeloperoxidase activity. Some of the cationic proteins and lysozyme were not found in leukemic myeloblasts but were present in particles of chronic myelogenous leukemia; alkaline phosphatase was absent from both types of leukemic cells.
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PMID:Granule assembly in precursors of human leukemia granulocytes. 451 81

Lactoferrin is contained in cytoplasmic granules of human polymorphonuclear leukocytes. Upon centrifugation, it sediments in a band of granules that also contain 50% of the lysozyme activity. This granule class is distinct from others associated with alkaline phosphatase and peroxidase. The granules are latent for lactoferrin as only lysed granules have the capacity specifically to inhibit antigen binding by anti-lactoferrin serum.
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PMID:Association of lactoferrin with lysozyme in granules of human polymorphonuclear leukocytes. 467 83

The sequential discharge of neutrophilic polymorphonuclear leukocyte (PMN) granules-azurophils and specifics-was investigated by electron microscopy and cytochemistry. Thus the enzyme content of PMN phagocytic vacuoles was determined at brief intervals after phagocytosis of bacteria, utilizing peroxidase as a marker enzyme for azurophil granules, and alkaline phosphatase for specifics. At 30 s, approximately half the phagocytic vacuoles were reactive for alkaline phosphatase, whereas none contained peroxidase. Peroxidase-containing vacuoles were rarely seen at 1 min, but by 3 min, vacuoles containing both enzymes were consistently present. Alkaline phosphatase was found in both small and large vacuoles, whereas peroxidase was visible only in large ones. By 10 min, very big phagocytic vacuoles containing considerable amounts of reaction product for both enzymes were evident. These observations indicate that the two types of PMN granules discharge in a sequential manner, specific granules fusing with the vacuole before azurophils. In an earlier paper, we reported that the pH of phagocytic vacuoles drops to 6.5 within 3 min and to approximately 4 within 7-15 min. Substances known to be present in specific granules (alkaline phosphatase, lysozyme, and lactoferrin) function best at neutral or alkaline pH, whereas most of those contained in azurophil granules (i.e., peroxidase and the lysosomal enzymes) have pH optima in the acid range. Hence the sequence of granule discharge roughly parallels the change in pH, thereby providing optimal conditions for coordinated activity of granule contents.
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PMID:Sequential degranulation of the two types of polymorphonuclear leukocyte granules during phagocytosis of microorganisms. 472 3

The various layers of the cell envelope of marine pseudomonad B-16 (ATCC 19855) have been separated from the cells and assayed directly for alkaline phosphatase activity under conditions established previously to be optimum for maintenance of the activity of the enzyme. Under conditions known to lead to the release of the contents of the periplasmic space from the cells, over 90% of the alkaline phosphatase was released into the medium. Neither the loosely bound outer layer nor the outer double-track layer (cell wall membrane) showed significant activity. A small amount of the alkaline phosphatase activity of the cells remained associated with the mureinoplasts when the outer layers of the cell wall were removed. Upon treatment of the mureinoplasts with lysozyme, some alkaline phosphatase was released into the medium and some remained with the protoplasts formed. Cells washed and suspended in 0.5 M NaCl were lysed by treatment with 2% toluene, and 95% of the alkaline phosphatase in the cells was released into the medium. Cells washed and suspended in complete salts solution (0.3 M NaCl, 0.05 M MgSO(4), and 0.01 M KCl) or 0.05 M MgSO(4) appeared intact after treatment with toluene but lost 50 and 10%, respectively, of their alkaline phosphatase. The results suggest that the presence of Mg(2+) in the cell wall is necessary to prevent disruption of the cells by toluene and may also be required to prevent the release of alkaline phosphatase by toluene when disruption of the cells by toluene does not take place.
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PMID:Biochemical localization of alkaline phosphatase in the cell wall of a marine pseudomonad. 481 47

Hypertonic sucrose inhibited the bactericidal activity of lysozyme-free serum against a rough strain of Escherichia coli. The duration of the inhibition correlated with the duration of plasmolysis caused by the sucrose. Although the lethal action of the serum was delayed, the prompt release of alkaline phosphatase by the cells suggested that nonlethal damage to the cell wall had taken place under these conditions. In contrast, the crypticity of the cells for beta-galactosidase did not deteriorate until the viability of the bacteria began to decrease. It is concluded that the primary site of action of serum is at the bacterial cell wall; however, in the absence of lysozyme, the lethal event was subsequent damage to the bacterial cell membrane.
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PMID:Locus of the lethal event in the serum bactericidal reaction. 488 4

The Escherichia coli structural gene for alkaline phosphatase was inserted into Salmonella typhimurium by episomal transfer in order to determine whether this enzyme would continue to be localized to the periplasmic space of the bacterium even though it was formed in a cell that does not synthesize alkaline phosphatase. The S. typhimurium heterogenote synthesized alkaline phosphatase under conditions identical to that observed with E. coli. This enzyme appeared to be identical to that synthesized by E. coli, and was quantitatively released from the bacterial cell by spheroplast formation with lysozyme. These results showed that localization is not a property unique to the E. coli cell and suggested that, in E. coli, enzyme location is related to the structure of the protein. Formation of alkaline phosphatase in the S. typhimurium heterogenote was repressed in cells growing in a medium with excess inorganic phosphate, even though only one of the three regulatory genes for this enzyme is on the episome. Thus, S. typhimurium can supply the products of the other two regulatory genes essential for repression even though this bacterium seems to lack the structural gene for alkaline phosphatase.
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PMID:Expression and localization of Escherichia coli alkaline phosphatase synthesized in Salmonella typhimurium cytoplasm. 488 17

Four proteins, which have been designated A, B, C and D, have been purified from human parotid saliva. These proteins are the major constituents of parotid saliva which migrate rapidly to the anode in polyacrylamide electrophoresis at pH9.5. Gel filtration and polyacrylamide electrophoresis were employed in the purification procedures. After purification all four preparations were tested for homogeneity by electrophoresis at pH2.8 and 9.5, by isoelectric focusing in the pH range 3-10, by immunodiffusion, and by sedimentation in the analytical ultracentrifuge. None of the proteins showed significant activity in assays for amylase, acid and alkaline phosphatase, protease, lysozyme, ribonuclease, peroxidase, beta-glucuronidase, beta-galactosidase, iron-binding activity and esterase. No cross-reactions were detected with antisera specific for lactoferrin and 15 serum proteins. All four proteins were rich in glutamic acid, proline and glycine and were lacking completely the sulphur-containing amino acids. Proteins A and C contained no threonine or tyrosine. Carbohydrate could be demonstrated only in protein A at a concentration of 4% of the total protein.
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PMID:Purification and partial characterization of four proteins from human parotid saliva. 500 93

Fractionation of rabbit heterophil leukocyte homogenates by isopycnic centrifugation as well as by zonal sedimentation has helped to characterize further the particulate components of these cells. Four classes have been identified: (A) Large (0.5-0.8 microm) and dense (1.26) azurophil or primary granules, containing all the myeloperoxidase, one-third of the lysozyme, and a major proportion of the lysosomal acid hydrolase activities of the cells. (B) Smaller (0.25-0.40 microm) and less dense (1.23) specific or secondary granules, containing 90% of the alkaline phosphatase and the remainder of the lysozyme activities, but very little if any acid hydrolases. (C) Particles of low density (1.20), containing the remainder of the lysosomal acid hydrolases. This fraction was heterogeneous, but showed abundant small rod- or dumbbell-shaped particles of moderate electron opacity, surrounded by a single membrane (tertiary granules?). The possible origin of these lysosomes from contaminating macrophages could not be ruled out but appeared unlikely. (D) Slowly sedimenting material of very low density (1.14), made up of large, empty vesicular membrane structures, and containing 10% of the alkaline phosphatase, and all of a thiol-dependent acid p-nitrophenyl phosphatase, an enzyme clearly different from the lysosomal acid phosphatase.
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PMID:Further biochemical and morphological studies of granule fractions from rabbit heterophil leukocytes. 545 43


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