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)

Thrombin-induced platelet microbicidal protein (PMP) is considered to play an important role in preventing an important role in preventing streptococcal endocarditis. However, the structural features and functions of PMPs have not been well characterized, and their antibacterial spectra against other common endocarditis pathogens, such as the staphylococci, are not known. Thrombin stimulation of washed rabbit platelets (10(8)/ml) yielded a PMP-rich preparation with a specific activity of approximately 25 U/mg of protein as determined by Bacillus subtilis bioassay. Twenty-eight clinical and laboratory Staphylococcus aureus isolates, exposed to a standardized PMP preparation (100 U/ml for 2 h at 37 degrees C), exhibited a Poisson-distributed heterogeneity to the bactericidal action of PMP, with approximately one-third designated as PMP resistant. Gel filtration chromatography (Sephadex G-50) identified the bioactive moiety within PMP preparations to be in the major protein elution peak; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) presumptively identified PMP as a low-molecular-weight (MW) (8,500) protein present only in such bioactive protein peaks. Both the bioactivity of PMP preparations and the low-MW protein band were removable by specific anionic membranes (e.g., cellulose-acetate/nitrate), as well as by a variety of anionic resins, further corroborating the suspected cationic charge of PMP. In addition, both PMP bioactivity and the low-MW protein band were recoverable by 1.5 M NaCl elution of the anionic membrane filters post-PMP adsorptive removal. Adsorption of bioactive PMP preparations by highly PMP-susceptible B. subtilis (10(8) CFU/ml, 30 min) resulted in a near-complete loss of residual bioactivity; in contrast, adsorption of bioactive PMP preparations with less PMP-susceptible S. aureus strains failed to reduce bioactivity. Significant lysozyme contamination of PMP-rich preparations was ruled out by determination of differences between bioactive PMP preparations and exogenous lysozyme as regards (i) relative heat stabilities; (ii) differential bactericidal activity versus B. subtilis and Micrococcus luteus; and (iii) SDS-PAGE protein profiles. These data show that the bioactive PMP protein moiety is of low MW, is heat stable, is probably cationic (similar to leukocyte-derived defensins), and possesses potent bactericidal activity against a significant percentage of S. aureus isolates.
...
PMID:Partial characterization and staphylocidal activity of thrombin-induced platelet microbicidal protein. 154 35

Association of platelets and neutrophils is frequently observed within thrombi or inflammatory sites. Interactions between these two cell populations have been reported for the production of several mediators of inflammation such as hydrogen peroxides or leukotrienes. Another potential mediator of thrombosis and inflammation is paf-acether, which is synthesized by activated platelets and neutrophils. Since platelets form and release large amounts of the paf-acether precursor lyso paf-acether, platelet and neutrophil cooperation for paf-acether biosynthesis was investigated. Purified human neutrophils (4 x 10(6)/ml) stimulated by opsonized zymosan (ZC, 1 mg/ml) formed 4.5 +/- 2.5 ng/ml paf-acether. Human washed platelets (3 x 10(8)/ml) stimulated with thrombin (1 IU/ml) formed 0.60 +/- 0.43 ng/ml paf-acether. Platelets and neutrophils, incubated together and both stimulated by their specific agonist, formed more than twice as much paf-acether as did platelets and neutrophils separately (10.90 +/- 4.25 ng/ml, n = 6, P less than .001). The formation of lyso paf-acether and the release of lysozyme and LDH were unchanged under the cooperation conditions. The formation of paf-acether almost doubled (10.24 +/- 3.81 ng/ml paf-acether vs. 5.30 +/- 2.23, P less than .05, n = 4) when ZC-stimulated neutrophils were incubated with supernatants from thrombin-stimulated platelets as well as with synthetic lyso paf-acether. Extracted and purified lyso paf-acether from thrombin-stimulated platelets led to an increase of biosynthesis of paf-acether by neutrophils (13.86 +/- 2.26 ng/ml paf-acether vs. 5.76 +/- 0.38, P less than .05, n = 3). These results indicate that a cooperation between platelets and neutrophils exists for paf-acether formation. The phenomenon depends on a platelet-derived soluble factor, possibly lyso paf-acether. This cell-to-cell interaction is of interest since paf-acether is formed by and acting on platelets and neutrophils and represents a molecular basis for potent amplification of inflammatory reactions.
...
PMID:Cooperation between platelets and neutrophils for paf-acether (platelet-activating factor) formation. 230 6

Platelets, basophils and neutrophils from a patient with the Wiskott-Aldrich syndrome (WAS) were exposed to stimuli that activate specific membrane receptor or directly initiate biochemical events (e.g. the Ca2+ ionophore A23187 and ionomycin or arachidonic acid). Platelets from this patient did not aggregate in response to ADP, collagen, thrombin or adrenaline, which activate specific membrane receptors. Platelet aggregation, however, was normal in response to compound A23187, ionomycin or exogenous arachidonic acid. Histamine release from basophils of the WAS patient was normal in response to anti-IgE, a formylated peptide (f-met peptide), and to A23187. Similarly, the release of the lysosomal enzymes, beta-glucuronidase and lysozyme, from neutrophils of the WAS patient in response to serum treated zymosan (Zx), f-met peptide, and A23187 was not significantly different from that of his parents and 13 normal donors. These results suggest that the primary defect in WAS is selectively present in platelets and is located in a biochemical step between receptor activation and Ca2+ influx and/or initiation of arachidonate metabolism.
...
PMID:The Wiskott-Aldrich syndrome: studies of platelets, basophils and polymorphonuclear leucocytes. 242 57

Polycationic molecules were studied either for their ability to displace the binding of basic fibroblast growth factor (bFGF) to high- and low-affinity membrane interaction sites and/or to modulate bFGF-induced proliferation of fibroblasts. Heparin-binding polypeptides, such as polylysine, protamine, histones, and thrombin-displaced [125I]bFGF bound to bovine brain membrane receptors. The most displacing polypeptides were those with the strongest affinity to heparin. Two of these polypeptides, protamine and polylysine, inhibited (at 5 microM) by more than 90% the mitogenic effect induced by bFGF on Chinese hamster lung fibroblast cells (CCL39). At the same dose, no effect was observed with basic proteins that do not bind to heparin, such as cytochrome C and lysozyme. An interesting observation was that protamine at 1 microM potentiated by 1.5-fold the mitogenic activity of bFGF, while it acted as an inhibitor at higher concentration.
...
PMID:Modulation of mitogenic activity and cellular binding of basic fibroblast growth factor by basic proteins. 272 69

Fibrin formation and turnover are intimately associated with inflammation and wound healing. To explore whether fibrin(ogen)-derived peptides exert direct effects upon cells involved in inflammation and tissue repair we examined the capacity of human fibrinopeptide B (hFpB), a thrombin-derived proteolytic cleavage product of the fibrinogen B beta-chain, to stimulate neutrophils (PMN), monocytes, and fibroblasts. hFpB caused directed cell migration of PMN and fibroblasts that was optimal at approximately 10(-8) M. This chemotactic activity was blocked by preincubating hFpB with antiserum to hFpB. hFpB was not chemotactic for monocytes. The chemotactic potency of hFpB for PMN was equivalent to that of anaphylatoxin from the fifth component of human complement (C5a), leukotriene B4 (LTB4), and formyl-methionyl-leucyl-phenylalanine (fMLP), and for fibroblasts its chemotactic activity was comparable to that of platelet-derived growth factor. hFpB did not interact with PMN receptors for C5a, LTB4, or fMLP as (a) desensitization with 10(-7) M hFpB abolished chemotaxis to hFpB but had no effect upon chemotaxis to C5a, LTB4, or fMLP and (b) induction of chemotactic responses to fMLP and LTB4 in neutrophilic leukemic cells (HL-60 cells) by incubation with dimethylsulfoxide did not extend to hFpB. Like fMLP, hFpB caused a rapid, dose-dependent increase in PMN cytoskeletal associated actin, but unlike fMLP, hFpB did not cause PMN aggregation, release of lysosomal enzymes (lysozyme and beta-glucuronidase), or the production of superoxide anion. These results suggest that hFpB may have a role in recruiting PMN and fibroblasts at sites of fibrin deposition and turnover. The capacity of hFpB to cause PMN chemotaxis without causing concurrent release of lysosomal enzymes or the production of superoxide anion is further evidence for the complexity of PMN responses to chemotactic agents.
...
PMID:Effects of fibrinogen derivatives upon the inflammatory response. Studies with human fibrinopeptide B. 300 61

Thrombin, a highly specific coagulation factor, can rapidly trigger lysozyme release from human neutrophils without concomitant activation of the 5-lipoxygenase pathway. This activation was not dependent on the presence of extracellular calcium. Since thrombin also induces the release of hemostatic and inflammatory metabolites from platelets and mast cells, it is proposed that it plays a significant role in amplification of the inflammatory response.
...
PMID:Thrombin-induced calcium-independent degranulation of human neutrophils. 309 81

Using immunochemical analysis with standard antisera, leukocyte thermostable alpha-glycoprotein (LT alpha G) was shown to be distinct from lactoferrin, lysozyme, and fibronectin. The determination of peroxidase and nonspecific elastase in immune precipitates of LT alpha G gave negative results. Affinity sorption of LT alpha G onto the pus protein component was revealed. Purified LT alpha G had amidolytic activity in response to a substrate for elastase (p-nitroanilide succinyl-trialanyl). The ability of LT alpha G to cause the hydrolysis of substrates for thrombin, kallikrein, plasmin was investigated. The identity of LT alpha G and granulocyte elastase is suggested.
...
PMID:[Thermostable leukocyte alpha-glycoprotein: immunochemical study and enzyme activity research]. 310 19

The effect of glycosaminoglycans (GAGs) such as sulodexide, low molecular mass dermatan sulfate, heparin and some derivatives with different degrees and types of sulfation was studied on cathepsin G- or thrombin-stimulated platelets and n-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated polymorphonuclear leucocytes (PMNs). All GAGs (0.01-20 micrograms/mL) inhibited both platelet aggregation induced by cathepsin G and its catalytic activity. Thrombin-induced platelet aggregation in contrast was only prevented by heparin, sulodexide and dermatan (2-100 micrograms/mL). All GAGs, except 2-O,N-desulfated heparin, inhibited beta-glucuronidase and lysozyme release, as well as beta-glucuronidase activity and PMN superoxide production by the peptide fMLP. The efficacy of GAGs was clearly dependent on the degree and type of sulfation since dermatan and N-desulfated heparins were comparatively less effective. The observation that heparin and other GAGs inhibit platelet activation induced by the PMN protease cathepsin G may help determine whether mechanisms of action other than anticoagulation are critical in the antithrombotic activity of heparin and related compounds.
...
PMID:Effects of glycosaminoglycans on platelet and leucocyte function: role of N-sulfation. 837 48

Identification of Na+ binding sites in protein crystals is complicated by comparable electron density of this monovalent cation and water. Valence calculations can predict the location of metal ion binding sites in proteins with high precision. These calculations were used to screen 332,242 water molecules in 2742 protein structures reported in the Protein Data Bank (PDB), searching for molecules with Na+/- specific valence values V(Na+) > or = 1.0 v.u., as expected for a bound Na ion. Thirty-three water molecules (<0.01% of the total) were found be have V(Na+) > or = 1.0 v.u. and to be located within 3.5 A from at least two protein oxygen atoms. These water molecules, with a high Na+ -specific valence, do not have valences specific for other cations, like Li+, K+, Mg2+ or Ca2+. They belong to nine different proteins (deoxyribonuclease I, enolase, hen egg-white lysozyme, human lysozyme, phospholipase A2, proteinase A, rubredoxin, thrombin and phage T4 lysozyme) and appear with similar coordination geometry, typically octahedral, in the same place in multiple crystal structure determinations of the same protein. In the case of thrombin, the water molecule singled out by valence calculations is, in fact, a bound Na ion as demonstrated by molecular replacement with Rb+. Valence calculations provide an accurate screening of water in protein crystals and may help identify Na+ binding sites of functional importance.
...
PMID:Valence screening of water in protein crystals reveals potential Na+ binding sites. 859 92

An arachidonic acid-stimulated Ser/Thr phosphatase activity was detected in soluble extracts prepared from rat pituitary clonal GH4C1 cells, rat or bovine brain, and bovine heart. The enzyme activity was purified to homogeneity from bovine brain as a monomer with a Mr of 63,000 and a specific activity of 32 nmol of Pi released per min/mg of protein when assayed in the presence of 10 microM phosphocasein in the absence of lipid. Arachidonic acid stimulated activity 4-14-fold, with half-maximal stimulation at 50-100 microM, when assayed in the presence of a variety of phosphosubstrates including casein, reduced carboxamidomethylated and maleylated lysozyme, myelin basic protein, and histone. Oleic acid, linoleic acid, and palmitoleic acid also stimulated activity; however, saturated fatty acids and alcohol or methyl ester derivatives of fatty acids did not significantly affect activity. The lipid-stimulated phosphatase was identified as the bovine equivalent of protein phosphatase 5 or a closely related homolog by sequence analysis of proteolytic fragments generated from the purified enzyme. When recombinant rat protein phosphatase 5 was expressed as a cleavable glutathione S-transferase fusion protein, the affinity-purified thrombin-cleaved enzyme exhibited a specific activity and sensitivity to arachidonic acid similar to those of the purified bovine brain enzyme. These results suggest that protein phosphatase 5 may be regulated in vivo by a lipid second messenger or another endogenous activator.
...
PMID:Purification of a fatty acid-stimulated protein-serine/threonine phosphatase from bovine brain and its identification as a homolog of protein phosphatase 5. 927 97


1 2 3 4 5 6 Next >>

---