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)

The lysozyme of bacteriophage T7 is a bifunctional protein that cuts amide bonds in the bacterial cell wall and binds to and inhibits transcription by T7 RNA polymerase. The structure of a mutant T7 lysozyme has been determined by x-ray crystallography and refined at 2.2-A resolution. The protein folds into an alpha/beta-sheet structure that has a prominent cleft. A zinc atom is located in the cleft, bound directly to three amino acids and, through a water molecule, to a fourth. Zinc is required for amidase activity but not for inhibition of T7 RNA polymerase. Alignment of the zinc ligands of T7 lysozyme with those of carboxypeptidase A and thermolysin suggests structural similarity among the catalytic sites for the amidase and these zinc proteases. Mutational analysis identified presumed catalytic residues for amidase activity within the cleft and a surface that appears to be the site of binding to T7 RNA polymerase. Binding of T7 RNA polymerase inhibits amidase activity.
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PMID:The structure of bacteriophage T7 lysozyme, a zinc amidase and an inhibitor of T7 RNA polymerase. 817 Oct 31

Pseudomonas stutzeri RS34 is a less sensitive member of pseudomonads to toxic effect of EDTA, the effect of EDTA is more bacteristatic than bactericidal, and can be reversed by divalent cations. Zn2+ provides more specific protection than Mg2+. EDTA-treated cells show higher sensitivity to lysozyme confirming the chelating mode of action of EDTA that leads to destabilization of the outer membrane. Such metal resistant bacteria can be profitably employed in the removal of metals from polluted ecosystems.
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PMID:Growth response of Pseudomonas stutzeri RS34 to ethylenediaminetetraacetic acid (EDTA) and its interaction with zinc. 822 14

The antibacterial effects of various forms of lactoferrin on enterotoxigenic strains of Escherichia coli were tested in vitro using a microassay for bacterial growth. Native and apo-lactoferrin exhibited variable activity against 19 strains, whereas holo-lactoferrin had no effect. At a concentration of .2 mg/ml of apo-lactoferrin, strains could be distinguished as either sensitive or resistant to inhibition. Zinc-saturated lactoferrin was as inhibitory as apo-lactoferrin when sensitive and resistant strains were tested over the concentration range .04 to 1.0 mg/ml of lactoferrin. A bactericidal effect was observed for native, apo-, and Zn-saturated lactoferrin against some sensitive strains. The antibacterial activity of apo-lactoferrin depended on bacterial inoculum size and was not enhanced by the addition of lysozyme. Addition of holo-lactoferrin or cytochrome c diminished the antibacterial effect of apo-lactoferrin, whereas addition of BSA had no effect. Resistance to inhibition by lactoferrin was not related to the production of bacterial siderophores.
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PMID:Forms of lactoferrin: their antibacterial effect on enterotoxigenic Escherichia coli. 822 60

Microbiostatic mechanisms may contribute substantially to host defense against infection by certain microbes. We studied the candidastatic activity of human neutrophils, neutrophil cytosol, and neutrophil-derived "calprotectin," a cytosolic protein complex comprised of two subunits, MRP8 and MRP14. Intact neutrophils, neutrophil lysates (prepared by ultrasonic disruption, freezing and thawing, or nonionic detergent extraction), and granule-depleted neutrophil cytosol were effective in restricting the growth of Candida albicans in a nutrient-rich tissue culture medium, RPMI 1640. Neither a subcellular fraction enriched in neutrophil granules nor selected purified granule components (lactoferrin, myeloperoxidase, cathepsin G, leukocyte elastase, lysozyme, and defensins) exerted candidastatic activity in this medium. Gel filtration liquid chromatography, anion exchange FPLC, and SDS-PAGE showed that the fungistatic factor in neutrophil cytosol was associated with the calprotectin complex. Its antifungal effects included restriction of yeast phase and mycelial growth and inhibition of glucose incorporation by yeast phase cultures. The antifungal effects of calprotectin were sustained for over 120 h and were inhibited by zinc. However, studies with 65Zn-enriched RPMI suggested that the candidastatic effects of calprotectin were not mediated by sequestration or binding of zinc. After reversed phase HPLC, calprotectin fractions containing MRP14 exhibited fungistatic activity, whereas fractions depleted of MRP14 but enriched for MRP8 lacked fungistatic activity. The results support a potentially significant role for the calprotectin complex of neutrophil cytosol in antifungal defense and suggest that MRP14 is of key importance in that activity.
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PMID:In vitro candidastatic properties of the human neutrophil calprotectin complex. 824 68

Monitoring of microbial DNA in soils by dot blot hybridization and PCR analysis is a useful technique for gaining insight into the survival and impact of genetically modified micro-organisms released in the environment. Most methods of DNA isolation from soils require a large number of purification steps rendering them unsuitable for quantitative analysis of multiple samples. Here we describe a very rapid method for the isolation and purification of multiple samples of soil DNA that can be used directly for dot blot hybridization and PCR analysis. Soil DNA extracts are prepared by lysozyme/SDS treatment at pH 9.0 and purified by ammonium acetate precipitation and Sephadex G50 gel filtration. In a practical application of this method, sandy soil samples were seeded with Alcaligenes eutrophus cells and exposed to high temperature (42 degrees C) or desiccation. As a result, the number of culturable A. eutrophus cells which could be recovered from the soil samples quickly declined. However, the concentration of a marker gene encoding resistance to cadmium, cobalt and zinc (czc) remained unaltered.
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PMID:Rapid method for purification of soil DNA for hybridization and PCR analysis. 826 Nov 67

It has been proposed that the binding of Zn2+ to alpha-lactalbumin switches the conformation to one akin to a state intermediate in the folding of the protein. However, the high resolution x-ray crystal structure of human alpha-lactalbumin-Zn2+ complex at 1.7-A resolution (pH 7.6) does not reveal any significant change in conformation from the native state. The Zn2+ ion binds specifically in the "cleft" of alpha-lactalbumin (the region which forms the active site of the homologous protein lysozyme). This may suggest a possible role for Zn2+ binding in lactose synthase complex. The coordination of the Zn2+ ion involves a symmetry-related molecule in the crystal, the crystal contacts being stabilized by a SO4(2-) ion bound at the interface between three molecules.
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PMID:Alpha-lactalbumin possesses a distinct zinc binding site. 836 79

We have detected a protein phosphatase activity in soluble extracts from the halophilic archaeon Haloferax volcanii. This activity was markedly stimulated by the divalent metal ions Mn2+ and Cd2+. It dephosphorylated phosphoseryl residues in casein, mixed histones, and phosphorylase a, but not phosphotyrosyl residues in reduced, carboxyamidomethylated and maleylated lysozyme. This protein phosphatase activity was inhibited by NaF, Zn2+, vanadate, molybdate, inorganic phosphate, inorganic pyrophosphate, or p-nitrophenyl phosphate, or by treatment with diethylpyrocarbonate. Activity was unaffected by other potential inhibitors or activators such as polyamines, heparin, cyclic nucleotides, Ca2+/calmodulin, tartrate, tetramisole, okadaic acid, microcystin LR, or sulfhydryl-modifying agents. The functional similarities between this protein-serine phosphatase and that previously identified in another archaeon, the extreme acidothermophile Sulfolobus solfataricus, suggest the existence of a family of divalent metal ion-stimulated protein-serine phosphatases of extremely ancient origin in the Archaea.
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PMID:A protein-serine phosphatase from the halophilic archaeon Haloferax volcanii. 839 5

A protein tyrosine phosphatase (PTP) containing two SH2 domains (PTP1C) was purified to near homogeneity from an adenovirus expression system by a two-step chromatographic procedure with a yield of 67%. The purified enzyme behaves as a monomer of 68 kDa on gel filtration and is totally specific for phosphotyrosyl residues. Its optimal pH is around neutrality for protein substrates such as reduced, carboxyamidomethylated, maleylated (RCM)-lysozyme and myelin basic protein but below 5 for low molecular weight compounds such as para-nitrophenyl phosphate (p-NPP) and phosphotyrosine. Furthermore, with the protein substrates, it displays an activity less than 1% of that obtained with other known PTPs but comparable activities toward p-NPP and phosphotyrosine. Its responsiveness toward the usual PTP activators (e.g. spermine) or inhibitors (e.g. vanadate, molybdate, heparin, or Zn2+) varied considerably with the nature of the substrates involved. Limited digestion with trypsin caused the cleavage of a C-terminal segment of the enzyme, giving rise to a 63-kDa fragment; this cleavage resulted in an approximately 20- and 10-fold activation of the enzyme toward RCM-lysozyme and myelin basic protein, respectively.
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PMID:Purification and characterization of a protein tyrosine phosphatase containing SH2 domains. 842 56

The sporulation-related gamma-D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 has been analysed by proton-induced X-ray emission. It contains 1 equivalent Zn2+ per mol of protein. As derived from gene cloning and sequencing, the B. sphaericus Zn peptidase I is a two-module protein. A 100-amino-acid-residue N-terminal domain consisting of two tandem segments of similar sequences, is fused to a 296-amino-acid-residue C-terminal catalytic domain. The catalytic domain belongs to the Zn carboxypeptidase A family, the closest match being observed with the Streptomyces griseus carboxypeptidase [Narahashi (1990) J. Biochem. 107, 879-886] and with the family prototype, bovine carboxypeptidase A. The catalytic domain of the B. sphaericus peptidase I possesses, distributed along the amino-acid sequence, peptide segments, a triad His162-Glu165-His307 and a dyad Tyr347-Glu366 that are equivalent to secondary structures, the zinc-binding triad His69-Glu72-His196 and the catalytic dyad Tyr248-Glu270 of bovine carboxypeptidase A respectively. The N-terminal repeats of the B. sphaericus peptidase I have similarity with the C-terminal repeats of the Enterococcus hirae muramidase 2, the Streptococcus (now Enterococcus) faecalis autolysin and the Bacillus phi PZA and phi 29 lysozymes, to which a role in the recognition of a particular moiety of the bacterial cell envelope has been tentatively assigned. Detergents enhance considerably the specific activity of the B. sphaericus peptidase I.
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PMID:Characterization of the sporulation-related gamma-D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 as a member of the metallo(zinc) carboxypeptidase A family. Modular design of the protein. 850 90

Protease Ci, a cytoplasmic metalloprotease in Escherichia coli, has been purified to apparent homogeneity by conventional chromatographic procedures using 125I-labeled oxidized insulin B-chain as a substrate. The purified enzyme behaves as a 54-kDa protein under both denaturing and nondenaturing conditions, suggesting that it consists of a single polypeptide chain. It is inhibited by metal-chelating agents, including o-phenanthroline and NaCN, but not by inhibitors of serine proteases or thiol-blocking agents. Furthermore, protease Ci was found to contain 1.1 mol of zinc per mol of the enzyme upon analysis by HR ICP mass spectroscopy. Thus, protease Ci must be a zinc metalloprotease. Among the polypeptides tested as substrates, oxidized insulin B-chain and glucagon are most rapidly hydrolyzed. Intact insulin is a much poorer substrate than oxidized insulin B-chain, even though the affinity of the enzyme to intact insulin is approximately 100-fold greater than that to the B-chain. Since unlabeled oxidized insulin A-chain is capable of inhibiting the hydrolysis of 125I-labeled insulin B-chain, it also appears to be a substrate. Protease Ci also degrades lysozyme and lactalbumin, although to a much lesser extent than oxidized insulin B-chain. However, it shows little or no activity against proteins larger than 15 kDa (e.g. ovalbumin and denatured bovine serum albumin). Hydrolysis of oxidized insulin B-chain followed by amino acid composition analyses of the cleavage products reveals that as many as 10 of its 29 peptide bonds are hydrolyzed by protease Ci. This ability to hydrolyze relatively small polypeptides suggests that protease Ci may catalyze the later steps in the pathway for intracellular protein breakdown.
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PMID:Purification and characterization of protease Ci, a cytoplasmic metalloendoprotease in Escherichia coli. 853 Mar 73


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