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)

Polyamines are natural constituents of most living organisms. However, their function in normal or pathological conditions is not fully understood. We have investigated in vitro effects of polyamines on characteristic properties of isolated renal brush-border membrane vesicles in order to determine whether polyamines have a regulatory role in membrane transport processes. The polyamines putrescine, spermidine and spermine were found to stimulate D-glucose uptake. Diffusional L-glucose uptake was not altered, indicating that the polyamines affected the active transport of D-glucose, rather than inducing nonspecific changes in membrane lipid properties. The amiloride-sensitive Na+ /H + exchange was slightly inhibited by polyamines while Mg2+ -ATPase activity was stimulated. The polyamine effects could not be explained solely by the polycationic properties of these agents, since polycationic polypeptides had an opposite effect. For example, lysozyme was found to inhibit D-glucose transport. Spermine was incorporated into the trichloroacetic acid-insoluble fraction of brush-border membrane proteins. Results indicated that this incorporation process consisted of at least two components: a Ca2+ -independent component and a Ca2+ -dependent component, possibly as a result of transglutaminase activity which was present in the isolated renal brush-border membranes. By using SDS-polyacrylamide gel electrophoresis in conjunction with fluorography, [3H]spermine was shown to be incorporated into several brush-border membrane proteins, mainly the 57 kDa, 74 kDa, 100 kDa, a heavy molecular weight band (greater than 200 kDa) and a low molecular weight band (less than 10 kDa). Our results suggest that the polyamine effects on membrane function may be due to a covalent modification of membrane proteins, possibly via a transglutaminase-mediated incorporation of polyamines or to the crosslinking of membrane proteins.
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PMID:Polyamines stimulate D-glucose transport in isolated renal brush-border membrane vesicles. 614 64

A human neutrophil protease, initially termed neutral peptide-generating protease, has been shown to cleave angiotensin II directly from angiotensinogen and has been identified as leukocyte cathepsin G. When purified neutrophils were disrupted by nitrogen cavitation and fractionated by differential centrifugation, 44 and 24% of the angiotensin II-generating activity was in the lysosomal and undisrupted cell fractions, respectively. Cytochalasin B-treated human neutrophils stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine released beta-glucuronidase, lysozyme, and angiotensin II-generating protease in a dose-dependent fashion, consistent with localization of this protease to the neutrophil granule. Individually purified angiotensin II-generating protease and cathepsin G had similar proteolytic and esterolytic activity for angiotensinogen and N-benzoyl-L-tyrosine ethyl ester on a weight basis, exhibited identical mobilities by SDS-gradient polyacrylamide gel electrophoresis and pH 4.3 disc-gel electrophoresis, and gave precipitin lines of antigenic identity on Ouchterlony analysis with goat antibody to the angiotensin II-generating protease. Thus, the angiotensin II-generating protease of human neutrophils has been identified as cathepsin G on the basis of subcellular localization, substrate specificity, physicochemical characteristics, and antigenic identity.
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PMID:Identification of a human neutrophil angiotension II-generating protease as cathepsin G. 617 48

To evaluate the role of NK cell granules in the lytic activity of NK cells, cytoplasmic granules of rat NK tumors were purified by centrifugation of the cell homogenates in a Percoll gradient. Analysis of such gradients showed a band of light-scattering material near the bottom of the tube; assay of gradient fractions for lytic activity against SRBC showed a potent lytic activity giving a sharp peak in this region. Complete lysis of SRBC was achieved with less than 1 microgram/ml protein of the most active fractions. Examination in the electron microscope showed that a pool of fractions containing lytic activity consisted of pure cytoplasmic granules showing similar morphology to those found in the LGL tumors. The lytic band was associated with a peak in the activity of four different lysosomal enzymes. Analysis of Percoll gradient fractions showed that marker enzymes for mitochondria, plasma membrane, and cytosol were well separated from this activity peak. Analysis of the Percoll gradient fractions by SDS gel electrophoresis showed that this granule fraction was free of contamination of proteins from other parts of the gradient. The granules contained major protein bands of 62, 58, 30, 29, and 28 kilodaltons. In addition to protein, the purified granule fractions contain hexose and uronic acid, but no nucleic acids or phospholipids were detected in chemical assays. Major amounts of chymotryptic, tryptic, and elastase activities were not present, nor were peroxidase or lysozyme activities detectable in substantial amounts. These data show that NK tumor cell cytoplasmic granules contain a potent lytic activity and have biochemical properties that distinguish them from granules present in granulocytes and mast cells.
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PMID:Purification and properties of cytoplasmic granules from cytotoxic rat LGL tumors. 637 25

Exposure of serum-susceptible Escherichia coli strains to lethal concns of lysozyme-free human serum resulted in stable binding of complement components to the outer membrane (OM), but not to the cytoplasmic membrane (CM). The short prekilling phase of the reaction was accompanied by binding of C3b; loss of viability was immediately preceeded by stable deposition onto the OM of the component proteins of the membrane attack complex. During the early stages of the active killing phase, bound monomeric C9 could be resolved into two distinct bands on SDS-polyacrylamide gels. Serum exposure lead to a progressive loss of CM recoverability, which appeared to result from partial degradation of CM phospholipids. In contrast, exposure of a resistant E, coli strain to human serum resulted in little change in the membrane profile and very little stable deposition of terminal complement components onto the OM.
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PMID:Interaction of human complement proteins with serum-sensitive and serum-resistant strains of Escherichia coli. 637 18

A method has been established which isolated polysomes from the lysozyme/EDTA-shocked cyanobacterium, Nostoc sp. MAC. In a typical preparation the total recovery of RNA as polysomes was 83%, in which 77% of the polysome fraction was present at sizes greater than 5-mers and 23% as 2-4-mers. Messenger RNA isolated from such a preparation of polysomes produced a 10-fold stimulation in the incorporation of [35S]methionine into polypeptides by a cell-free system of Escherichia coli. The in vitro-synthesized polypeptides were analysed on an SDS-polyacrylamide gradient gel together with in vivo-labelled proteins of Nostoc sp. MAC: seven polypeptides co-migrated with the in vivo-synthesized products. This is the first report of the expression of cyanobacterial messenger RNA in a heterologous cell-free system from E. coli; the efficiency of the system is discussed.
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PMID:Isolation of polysomes from Nostoc sp. MAC and translation of messenger RNA in a heterologous cell-free system. 641 28

Polypeptide and polysaccharide outer membrane components of Brucella abortus 99 (S) were investigated by analysis of cell-wall fractions by sodium dodecyl-sulfate polyacrylamide gel electrophoresis and staining with coomassie blue and periodic acid silver stain. Crude cell-walls were deprived by Triton X-100 treatment of most cytoplasmic material as seen by electron microscopy and cytochrome determination (cell-walls). They were submitted to hot SDS to obtain intentionally after centrifugation, peptidoglycan in the insoluble fraction: SDS-I fractions or peptidoglycan sacculi, and outer membrane components in the SDS soluble fraction as for Enterobacteriaceae. The SDS-soluble fraction contained two major components: a high molecular weight broad band of smooth lipopolysaccharide (S-LPS) and a 43k polypeptide band. The SDS-I fractions were treated by lysozyme to solubilize peptidoglycan before analysis. They contained two major polypeptide groups 36-37-38k, 25-26-27k, a minor one at 31k and variable amounts of high molecular weight S-LPS. The polypeptide and polysaccharide patterns of the entire outer membrane obtained from lysozyme hydrolysed cell-walls are the sum of both SDS soluble and insoluble fraction patterns. These results mean that 25-27k and 36-38k bands are strongly bound to peptidoglycan, probably covalently. The 25-26-27k bands heavily stained for polysaccharides would be glycopolypeptides. In addition, the polysaccharide patterns of S-LPS fraction appears as a high molecular weight broad band, contrary to the multiple regularly spaced bands of high molecular weight E. coli S-LPS. The B. abortus outer membrane is composed of four major components: LPS, 43k and 36-37-38k polypeptides and 25-26-27k glycopeptides.
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PMID:Evidence of three major polypeptide species and two major polysaccharide species in the Brucella outer membrane. 641 68

Natural and synthetic antioxidants have been shown to repair tryptophan radicals produced from the one-electron oxidation of the free tryptophan amino acid. It has also been observed that both tryptophan and tyrosine radicals in lysozyme can be repaired by these antioxidants to varying degrees of efficiency. Although SDS-solubilized alpha-tocopherol efficiently repairs free tryptophan radicals, it is very inefficient in repairing the amino acids in lysozyme. The rigidity and immobility of solubilized alpha-tocopherol can explain this lack of efficiency.
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PMID:The repair of oxidized amino acids by antioxidants. 650 64

The occurrence of post-exercise proteinuria was investigated in intact and splenectomized dogs after treadmill running and swimming and compared to control experiments. Albumin and lysozyme were measured by radial diffusion. Urinary protein was analyzed by SDS-polyacrylamide gel electrophoresis. Swimming in the splenectomized dogs increased the albumin excretion in the first 30 min after exercise from 0.03 to 0.22 mg X min-1 and the lysozyme excretion in the same period from 0.11 to 0.75 micrograms X min-1. Swimming in intact dogs caused smaller increase in the lysozyme and albumin excretions during the exercise period itself as well as in the albumin excretion in the first 30 min after exercise. Running had no effect on urinary albumin or lysozyme but increased the low molecular weight protein fraction in the splenectomized dogs. Plasma lactate concentrations were higher during swimming in the splenectomized dogs than in the intact dogs. Possible mechanisms of post-exercise proteinuria are discussed.
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PMID:Proteinuria in intact and splenectomized dogs after running and swimming. 651 Nov 48

Protein A (PA)-activity was detected in Staphylococcus aureus strain Wood 46 which had been considered to be PA-negative. This staphylococcal strain bound 28% of 125I-labelled IgG, compared with 89% by strain Cowan I. The binding activities of both S. aureus strains were saturable, time-dependent and specific. The dissociation constants of 1.6 X 10(-9) M for Wood 46 and 9.3 X 10(-8) M for Cowan I indicated a similar affinity for human IgG in both strains. The number of IgG-binding sites were estimated to be 16,970 for Wood 46 and 41,200 for Cowan I. Exposure to heat and ultrasonication reduced PA-activities of strain Cowan I, but not that of strain Wood 46. Extraction of the staphylococci with guanidine and formic acid resulted in a reduction of IgG-binding activities only in strain Wood 46. Photooxidation, trypsinization and lysozyme treatment also diminished IgG-binding of strain Wood 46 to a larger extent than that of strain Cowan I. Extracellular PA from S. aureus strains Wood 46 and Cowan I could be purified by affinity chromatography on IgG-sepharose. The purified PA preparations gave single protein bands upon SDS-polyacrylamide gel electrophoresis. Their molecular weights were 42,000 and their isoelectric points approximated 5.0.
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PMID:Characterization of immunoglobulin G binding to Staphylococcus aureus strain Wood 46. 653 38

Using strains of Streptococcus mutans suspended in human saliva, the salivary proteins capable of binding to the surface of the bacteria were identified by immunological and electrophoretic techniques. Six binding components were recognized: IgA, lysozyme, some high molecular weight material (greater than 400,000), probably a glycoprotein, a low molecular weight component (11-13,000), a 150,000 mol. wt protein, and one major component, mol. wt 20-25,000 which did not resolve fully on SDS-polyacrylamide electrophoresis. All these salivary components could be desorbed from the bacteria with 1 M NaCl, and subsequent extraction of the same cells with 6 M guanidine-HCl did not release any more salivary material. The significance of the binding of these salivary components is unknown but some may modify the behaviour of the organisms in vivo.
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PMID:The adsorption of human salivary components to strains of the bacterium Streptococcus mutans. 659 86


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