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)

Groups of rabbits were exposed by inhalation to chlorides of cobalt, nickel, and manganese as well as to tri- and hexavalent chromium at metal concentrations ranging from 0.4 to 3.9 mg/m3 for 1-4 months (5 days/week, 6 hr/day). Fibronectin content and lysozyme (muramidase) activity in lavage fluid were measured after all treatments and in alveolar macrophages after treatment with nickel chloride. In the lavage fluid no marked changes were seen in fibronectin content and lysozyme activity after exposure to tri- or hexavalent chromium or manganese. Nickel exposure significantly decreased the lysozyme activity in the lavage fluid and in the macrophages whereas the fibronectin content was unchanged in the lavage fluid and significantly increased in the macrophages. Both fibronectin content and lysozyme activity were increased markedly in the lavage fluid after cobalt exposure.
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PMID:Fibronectin concentrations in lung lavage fluid after inhalation exposure to low levels of metals. 358 6

Manganese is accumulated in Bacillus subtilis by a highly specific active transport system. This trace element "pump" is insensitive to added magnesium or calcium and preferentially accumulates manganese in the presence of cobalt, iron, and copper. Manganese uptake in B. subtilis is inhibited by cyanide, azide, pentachlorophenol, and m-chlorophenyl carbonylcyanide hydrazone. The uptake of manganese follows Michaelis-Menten kinetics, and the net accumulation of manganese is regulated by increasing the V(max) after exposure to manganese-starvation conditions and by decreasing the V(max) for manganese uptake during growth in excess manganese. The K(m) remains constant during these regulatory changes in V(max). Manganese accumulated during growth is exchangeable for exogenous manganese and can be released from the cells by toluene (which causes leakage but not lysis) or by lysis with lysozyme. Two stages can be distinguished with regard to intracellular manganese during the process of growth and sporulation. During logarithmic growth, B. subtilis maintains a relatively constant internal manganese content, which is a function of the external manganese concentration following approximately a Langmuir adsorption isotherm. At the end of log phase, net accumulation of manganese slows. A second phase of net manganese accumulation begins at about the same time during sporulation as the accumulation of calcium begins. The manganese accumulated during growth and early sporulation is exchangeable and therefore relatively "free"; intracellular manganese is converted later during sporulation into a bound form that cannot be released by toluene or lysozyme.
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PMID:Manganese transport in Bacillus subtilis W23 during growth and sporulation. 463

The interactions have been studied of a water-soluble, polymeric derivative of prostaglandin B1, PGBX, with human polymorphonuclear leukocytes (PMN). PGBX, which is a potent ionophore of divalent cations, provoked superoxide anion (O2.-) generation and lysosomal enzyme release in cytochalasin B-treated PMN in the presence of extracellular divalent cations (Ca2+, Sr2+, Mg2+, Mn2+, Ba2+). Kinetic and dose-response studies showed that PGBX mimicked te action of ionophore A23187 in PMN. Both ionophores induced superoxide generation and release of enzymes from specific and azurophil granules (lysozyme > beta-glucuronidase) without provoking release of the cytoplasmic marker enzyme lactic dehydrogenase. In contrast, the precursor of PGBX, prostaglandin B1 (PGB1), and arachidonate did not mimic ionophore-induced stimulation of PMN. PGBX induced enzyme release both in the presence of extracellular Ca2+ and Ba2+ (both of which it translocates in model liposomes), whereas A23187 showed specificity for Ca2+ (which it translocates preferentially over Ba2+). These studies indicate that the actions of a water-soluble polymer (PGBX) derived from a naturally occurring prostaglandin (PGB1) on human neutrophils resemble those of a classical ionophore (A23187). Moreover, they provide additional evidence that increments in the intracellular levels of divalent cations may signal stimulus-secretion coupling in human neutrophils.
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PMID:PGBX, a prostagandin derivative, mimics the action of the calcium ionophore A23187 on human neutrophils. 625 62

Bacterial endospore germination is powerfully influenced by inorganic salts, cations having especially important effects. Spores of Clostridium perfringens 8-6 are unusual in lacking a spore coat; these spores germinate only in the presence of lysozyme, which readily digests the exposed cortex. Lysozyme-induced germination showed the same response to ionic strength and valence of cations as does lysozyme hydrolysis of peptidoglycan, and close parallels are evident in the influence of inorganic cations on germination of normal spores. La3+ and transition element cations inhibited lysozyme-induced germination at low concentration, again demonstrating parallels with their action on lysozyme digestion of peptidoglycan and on the germination of normal spores. The poly-cations poly(L-lysine) and Ruthenium Red inhibited at extremely low concentrations. Mn2+ and Co2+, at appropriately low concentrations, stimulated lysozyme germination of 8-6 spores and also lysis of Micrococcus lysodeikticus.
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PMID:Influence of cations on lysozyme-induced germination of coatless spores of Clostridium perfringens 8-6. 626 45

Diadenosine 5',5'''-P1,P4-tetraphosphate was shown by circular dichroic measurements to bind to metal ions (Mg2+, Ca2+, Mn2+, Co2+, Zn2+), to biogenic amines (cadaverine, putrescine, spermidine, spermine), to L-arginine, to proteins (lysozyme, bovine serum albumin, Arg-rich histone f3, Lys-rich histone), and to poly(dT). Most cations effect destacking of the intramolecular adenine rings. Poly(dT) bound to the dinucleotide with a stoichiometry of 2 residues TMP per molecule of adenosine 5',5'''-P1,P4-tetraphosphate.
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PMID:Noncovalent complexes of diadenosine 5',5"'-P1,P4-tetraphosphate with divalent metal ions, biogenic amines, proteins and poly(dT). 673 84

The effects of several divalent cations, various polybasic amines, and lysozyme on the rate of polymerization of 8S clathrin to the 300S coat structure have been evaluated by turbidimetric procedures. Ca2+ and Mn2+ strongly enhance the rate of polymerization. Only spermine among the naturally occurring polybasic amines had an important effect. Of the several basic proteins evaluated, only lysozyme stimulated the rate of polymerization. Some of these substances were able to increase the rate sufficiently so that polymerization occurred at physiological pH values. Without these compounds, clathrin will only polymerize at pH values of 6.8 or less.
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PMID:Effect of basic compounds on the polymerization of clathrin. 730 30

Beta-N-Acetylglucosaminidase has been purified from an acetone extract of Aspergillus niger. The protein has a Mr = 149,000. It contains neither Mn2+, Zn2+, nor cysteine and exhibits no cation requirement for activity. Isoelectric focusing separates two isozymes; the major isoenzyme has a pI = 4.4. Both isozymes exhibit beta-N-acetylgalactosaminidase and beta-glucosidase, as well as glucosaminidase activity. The mechanism of action of this enzyme has been studied in detail using a variety of substrate structure/activity and kinetic experiments. Rate data plotted versus pH depends on the following ionization constants, respectively: for pKm, 2.95; for log Kcat, 7.6; and for log kcat/Km, 2.95 and 8.25. The kcat value of H2O/D2O for p-nitrophenyl-beta-N-acetylglucosaminide hydrolysis is 1.27 at pH 4.6 and 1.00 at pH 7.0. The rho value for the hydrolysis of para-substituted phenylglucosaminides is +0.36; rho for the hydrolysis of fluoro-substituted N-acetyl derivatives is -1.41. Two sulfur-containing substrate analogues, the 1-thioglucosaminide, and the N-thioacetyl derivative, exhibit either no or little substrate activity. The hydrolysis of the 2,4-dinitrophenyl-glucosaminide is not biphasic as indicated by stopped flow kinetic studies. These several results are interpreted to show that: 1) enzymatic nucleophilic catalysis is not employed by beta-N-acetylglucosaminidase; 2) the glycosidic oxygen is protonated very early in the reaction, perhaps even in the Michaelis complex; 3) the acetamido oxygen provides anchimeric assistance to hydrolysis via charge stabilization of the oxocarbonium ion (or via oxazoline formation); 4) additional charge stabilization is provided by an enzymic anion, perhaps a side chain carboxylate group. The role of the acetamido group is discussed and comparisons are made between lysozyme, beta-galactosidase, and beta-N-acetylglucosaminidase.
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PMID:Purification, properties, kinetics, and mechanism of beta-N-acetylglucosamidase from Aspergillus niger. 744 May 73

RPTP mu is a recently described receptor-like protein tyrosine phosphatase (PTP), the ectodomain of which mediates homophilic cell-cell adhesion. The cytoplasmic part contains two homologous PTP-like domains and a juxtamembrane region that is about twice as large as in other receptor-like PTPs. The entire 80-kDa cytoplasmic part of human RPTP mu was expressed in insect Sf9 cells and its enzymatic activity was characterized after purification to electrophoretic homogeneity. In addition, the effects of deletion and point mutations were analyzed following expression in Escherichia coli cells. The purified cytoplasmic part of RPTP mu displays high activity toward tyrosine-phosphorylated, modified lysozyme (Vmax 4500 nmol min-1 mg-1) and myelin basic protein (Vmax 8500 nmol min-1 mg-1) but negligible activity toward tyrosine-phosphorylated angiotensin or the nonapeptide, EDNDpYINASL, that serves as a good substrate for protein tyrosine phosphatase PTP1B. This suggests that RPTP mu and PTP1B have distinct substrate specificities. Catalytic activity is independent of Ca2+ (up to 1 mM) but is strongly inhibited by Zn2+, Mn2+, vanadate, phenylarsenic oxide, and heparin. The first of the two catalytic domains is 5-10 times less active than the expressed catalytic region containing both domains. Mutation of Cys 1095 to Ser in the first catalytic domain abolishes enzymatic activity when analyzed following expression in either E. coli or mammalian COS cells. Deletion of the first 53 amino acids from the juxtamembrane region reduces catalytic activity about 2-fold.
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PMID:Purification and characterization of the cytoplasmic domain of human receptor-like protein tyrosine phosphatase RPTP mu. 750 51

A full-length cDNA for a novel isoform of the human receptor tyrosine phosphatase gamma gene (PTPRG) was overexpressed in Sf9 insect cells, and the gene product, PTP gamma, was purified and characterized. The protein was expressed as a M(r) approximately 185,000 protein accompanied by a M(r) approximately 120,000 putative cleavage product on SDS-PAGE analysis. The protein undergoes N-linked glycosylation and constitutive phosphorylation of serine residues. When assayed for tyrosine-specific phosphatase activity, PTP gamma dephosphorylated myelin basic protein at a pH optimum of 7.5 and a Km of 12.6 microM; reduced carboxyamidomethylated and maleylated lysozyme (RCM-lysozyme) at a pH optimum of 6.0 and a Km of 12 microM; and p-nitrophenylphosphate with a pH optimum of 5.5 and a Km of 3.5 mM. Phosphatase activity was inhibited by ZnCl2 and sodium orthovanadate; Mg2+, Mn2+, and Ca2+ ions were ineffective. The partially purified form of the enzyme was allosterically activated by triphosphorylated nucleosides, with a preference for purines. This activation was prevented by Mg2+ addition and did not occur when a purified form of the enzyme was utilized, suggesting that its activation depends on specific activating factors or conformational constraints. Interestingly, PTP gamma protein was specifically bound by an ATP-agarose matrix through its intracellular domain, suggesting a link between binding of nucleotides and activation of the phosphatase.
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PMID:Characterization of the receptor protein tyrosine phosphatase gene product PTP gamma: binding and activation by triphosphorylated nucleosides. 758 20

A gamma-glutamyl peptide-hydrolysing enzyme was partially purified from Actinobacillus actinomycetemcomitans. The enzyme required metal ions, and 1 to 2 mM Mn2+ ions, especially, were essential for hydrolytic reaction. Its distribution by treatment of cells with lysozyme-EDTA suggested that the enzyme was a membrane-bound protein. The pI of the enzyme was in range of pH 5.1 to 5.6, and the apparent Km value for gamma-glutamyl-p-nitroanilide was 3.0 x 10(-4) M. The enzyme hydrolysed specifically gamma-glutamyl residues from the N-terminal of gamma-glutamyl compounds such as gamma-Glu-Met, gamma-Glu-Ala, gamma-Glu-Leu and gamma-Glu-Tyr, but did not catalyse the transpeptidation reaction. Neither free amino acids such as Ala-, Pro-, Gly- and Leu-p-nitroanilide nor alpha-glutamyl derivatives were hydrolysed. Its activity was strongly inactivated by metal chelators (EDTA or o-phenanthroline) and amino acids (Glu, Gln). In addition, the activity was specifically inactivated by gamma-glutamyl affinity-labelling reagents such as AT-125, 6-diazo-5-oxo-L-norleucine and azaserine, which are inhibitors of the gamma-glutamyl donor sites of mammalian gamma-glutamyl transpeptidase. Antibodies against bovine kidney gamma-glutamyl transpeptidase decreased the activity of the bacterial enzyme by 65%. These results suggested that the active sites in the bacterial enzyme were similar to those in mammalian gamma-glutamyl transpeptidase.
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PMID:Partial purification and some properties of gamma-glutamyl peptide-hydrolysing enzyme from Actinobacillus actinomycetemcomitans. 779 32


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