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)

Earlier, a sensitive turbidimetric method was reported (H.A. McKenzie and F.H. White, Jr. Biochem. Int. 14, 347-356, 1987), with which evidence was found for weak lysozyme-like activity in alpha-lactalbumin (alpha-LA) against Micrococcus luteus. Alternative methods have been developed for the further study of trace cell-lytic activity, and the results are compared with those of the turbidimetric technique. These methods involve (1) determination of weight loss from a suspension of bacterial cells after exposure to the protein under investigation, and (2) viability studies on the exposed cells. In addition, exposed and control cells were subjected to microscopic examination. Results from all studies were consistent with lysis of cells by alpha-LA as well as by lysozyme. Activities of alpha-LA from the three methods of assay, expressed as ratios to those of lysozyme, were 2.2-5.2 x 10(-5) (mean = 3.6 x 10(-5). The methods were assessed with respect to sources of error characteristic of each and to protein dose requirements for a specified level of cell killing. The turbidimetric approach remains useful for measuring cell-lytic activities as described here. However, caution is urged in its general use.
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PMID:Further studies on the lysozyme-like activity of alpha-lactalbumin: development of alternative methods of assay. 836 1

We describe a conserved family of bacterial gene products that includes the VirB1 virulence factor encoded by tumor-inducing plasmids of Agrobacterium spp., proteins involved in conjugative DNA transfer of broad-host-range bacterial plasmids, and gene products that may be involved in invasion by Shigella spp. and Salmonella enterica. Sequence analysis and structural modeling show that the proteins in this group are related to chicken egg white lysozyme and are likely to adopt a lysozyme-like structural fold. Based on their similarity to lysozyme, we predict that these proteins have glycosidase activity. Iterative data base searches with three conserved sequence motifs from this protein family detect a more distant relationship to bacterial and bacteriophage lytic transglycosylases, and goose egg white lysozyme. Two acidic residues in the VirB1 protein of Agrobacterium tumefaciens form a putative catalytic dyad, Each of these residues was changed into the corresponding amide by site-directed mutagenesis. Strains of A. tumefaciens that express mutated VirB1 proteins have a significantly reduced virulence. We hypothesize that many bacterial proteins involved in export of macromolecules belong to a widespread class of hydrolases and cleave beta-1,4-glycosidic bonds as part of their function.
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PMID:A family of lysozyme-like virulence factors in bacterial pathogens of plants and animals. 869 91

The protozoan parasite Entamoeba histolytica contains a second antibacterial protein with lysozyme-like properties. The newly recognized bacteriolytic protein was purified from extracts of amoebic trophozoites to allow amino-terminal sequencing. Subsequent molecular cloning revealed that it is an isoform of the amoeba lysozyme described previously but also demonstrated a substantial sequence divergence of the two forms. As lysozymes typically are basic proteins, the novel amoebic protein differs markedly in having a pI of 4.5. There is no significant similarity of both amoeba lysozymes with any bacteriolytic protein of other organisms reported so far; however, striking sequence identity is found with predicted gene products of unknown function derived from the bacteria-feeding nematode Caenorhabditis elegans.
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PMID:Molecular characterization of an exceptionally acidic lysozyme-like protein from the protozoon Entamoeba histolytica. 980 91

Salivary gland plasticity was a significant adaptive feature in the mammalian radiation. This plasticity is reflected in remarkable and well-documented interspecific phenotypic variation in gland ultrastructure and in the chemical components of saliva. However, comparative data are still too sparse for determination of evolutionary trends that combine phenotypic patterns with evolutionary history and the actual secretory products. Although our theoretical approach assumes that natural selection has taken advantage of salivary gland plasticity in gene regulation, gland development, and secretory cell organelles and processes, it still is difficult to delineate the biological roles of secretory products in the context of ecological adaptation. In the present investigation we used immunohistochemical techniques and a polyclonal antiserum against lysozyme to compare the parotid and principal submandibular glands in a set of 12 species of microchiropteran bats. With this data set we used comparative methods and phylogenetic trees to develop the foundations for testable hypotheses about the molecular genetics and adaptive significance of lysozyme production in bats. By comparing immunohistochemical results with ultrastructure, lysozyme-like immunoreactivity was associated with serous secretory granules in parotid gland acinar calls, parotid gland intercalated duct cells, and submandibular gland demilune cells. Lysozyme production in submandibular gland demilune cells marks a point of evolutionary divergence between three families of insectivorous bats and four families composed of species with diverse diets (ranging from carnivory to nectarivory). In terms of diet, lysozyme-like immunoreactivity corresponded most strongly with feeding on hard-bodied insects, leading to the hypothesis that lysozyme serves as an important chitinase in bat saliva.
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PMID:Plasticity and patterns of evolution in mammalian salivary glands: comparative immunohistochemistry of lysozyme in bats. 982 87

Lysozymes were purified from three invertebrates: a marine bivalve, a marine conch, and an earthworm. The purified lysozymes all showed a similar molecular weight of 13 kDa on SDS/PAGE. Their N-terminal sequences up to the 33rd residue determined here were apparently homologous among them; in addition, they had a homology with a partial sequence of a starfish lysozyme which had been reported before. The complete sequence of the bivalve lysozyme was determined by peptide mapping and subsequent sequence analysis. This was composed of 123 amino acids including as many as 14 cysteine residues and did not show a clear homology with the known types of lysozymes. However, the homology search of this protein on the protein or nucleic acid database revealed two homologous proteins. One of them was a gene product, CELF22 A3.6 of C. elegans, which was a functionally unknown protein. The other was an isopeptidase of a medicinal leech, named destabilase. Thus, a new type of lysozyme found in at least four species across the three classes of the invertebrates demonstrates a novel class of protein/lysozyme family in invertebrates. The bivalve lysozyme, first characterized here, showed extremely high protein stability and hen lysozyme-like enzymatic features.
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PMID:Amino acid sequences of lysozymes newly purified from invertebrates imply wide distribution of a novel class in the lysozyme family. 991 27

Intrinsic lysozyme-like activity was demonstrated for destabilase from the medicinal leech supported by (1) high specific lysozyme activity of the highly purified destabilase, (2) specific inhibition of the lysozyme-like activity by anti-destabilase antibodies, and (3) appreciable lysozyme-like activity in insect cells infected with recombinant baculoviruses carrying cDNAs encoding different isoforms of destabilase. Several isoforms of destabilase constitute a protein family at least two members of which are characterized by lysozyme activity. The corresponding gene family implies an ancient evolutionary history of the genes although the function(s) of various lysozymes in the leech remains unclear. Differences in primary structures of the destabilase family members and members of known lysozyme families allow one to assign the former to a new family of lysozymes. New proteins homologous to destabilase were recently described for Caenorhabditis elegans and bivalve mollusks suggesting that the new lysozyme family can be widely distributed among invertebrates. It remains to be investigated whether the two enzymatic activities (isopeptidase and lysozyme-like) are attributes of one and the same protein.
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PMID:Destabilase from the medicinal leech is a representative of a novel family of lysozymes. 1071 76

Lysozyme-like activity has been demonstrated in both cell-free haemolymph and, more abundantly, in haemocyte-lysate supernatants of Blaberus discoidalis. This activity was non-inducible, but heat-stable, with a maximum activity at pH 6.2. When B. cereus was pre-incubated in a concentration of chicken egg-white lysozyme equivalent to the concentration of lysozyme-like activity in cell-free haemolymph, the phagocytosis of B. cereus opsonized with GlcNAc-specific lectins, i.e. BDL2, WGA and HPA, was significantly reduced by up to 50%, while phagocytosis of B. cereus opsonized with mannose-specific lectins, such as BDL1 and Con A, was significantly increased. Pre-incubation of B. cereus in a higher concentration of lysozyme resulted in a smaller, shorter lived increase in the phagocytic rate of bacteria opsonized with these mannose-specific lectins. The action of lysozyme on the peptidoglycan in the cell wall of B. cereus probably resulted in a reduction in the number of binding sites for the GlcNAc-specific lectins, and, therefore, reduced the phagocytic rate of BDL2, HPA and WGA-opsonized B. cereus. Concomitantly, the breakdown of peptidoglycan probably exposed mannose-containing polysaccharides, previously embedded in the peptidoglycan layer, resulting in an increase in the phagocytic rate of the BDL1- and Con A-opsonized B. cereus. These results are discussed in relation to the immune-potential of B. discoidalis.
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PMID:Effect of lysozyme on the lectin-mediated phagocytosis of Bacillus cereus by haemocytes of the cockroach, Blaberus discoidalis. 1074 14

Antibacterial proteins are an important part of the innate immune system for all animals. They have been extensively studied in mammals, amphibians and invertebrates, but have received only scant attention in fish. Their expression and processing, however, provide a way of monitoring defence vigour during development or with seasonal changes in physiology. The aim of the present work was to identify and characterise antibacterial proteins in rainbow trout. In vitro analyses of extracts of the peripheral blood leucocytes, head kidney leucocytes and mucus from adult unstimulated (non-immune) fish showed marked antibacterial activity against Gram positive bacteria. Fractionation by ion exchange chromatography and RP-HPLC of head kidney extracts showed the presence of two forms of lysozyme but no constitutively expressed antimicrobial proteins of < 10 kDa. By contrast, chromatographic analyses of mucus revealed at least four antibacterial proteins. Two are conventional lysozymes, a third is an unusual lysozyme-like protein with a low isoelectric point, and the fourth is a highly hydrophobic, cationic peptide of c. 3 kDa.
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PMID:Antibacterial proteins in rainbow trout, Oncorhynchus mykiss. 1093 37

In a recent publication we reported the protein purification, characterization, and the gene isolation of a cDNA encoding the antibacterial cold-active lysozyme-like protein chlamysin from the marine bivalve Chlamys islandica. A 4.2 kb genomic chlamysin gene has now been amplified and sequence-analyzed. By comparison to the cDNA sequence and its translation product, the coding region was found separated in four exons of 38-252 bp. The introns range in size from 0.8 to 1.5 kb, and have traditional spliceosomal intron 5'-GT donor and 3'-AG acceptor sites for splicing. Two of the introns contain multiple copies of three sequence motifs not found repeated in other published genes. The over-all gene organization of chlamysin resembles chicken-type (c-type) lysozyme genes in vertebrates, but is different from the three-exon structure in invertebrate c-type lysozyme genes. A phylogenetic analysis of invertebrate-type (i-type) and c-type lysozyme proteins demonstrated a large evolutionary distance between the i-type and the c-type enzyme classes. Exons of the i-type genes are not equally organized according to their homolog protein domains.
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PMID:The gene of chlamysin, a marine invertebrate-type lysozyme, is organized similar to vertebrate but different from invertebrate chicken-type lysozyme genes. 1137 34

We report the presence of a unique, non-bacteriolytic, c (chicken or conventional type) lysozyme-like protein, SLLP1, in the acrosome of human sperm. C lysozymes are bacteriolytic and can also bind to N-acetylglucosamines linked by beta-1,4 glycosidic bonds. Most of the invariant residues (17 out of 20), including all the cysteines, were conserved in SLLP1, but the two catalytic residues E35 and D52 of c lysozymes were replaced with T and N, respectively. The full-length cDNA encodes a protein of 215 aa with a predicted protease cleavage site between A87 and K88. The processed form of SLLP1, which showed an exon-intron organization similar to human c lysozyme, was the major isoform in the acrosome of ejaculated sperm. As expected, based on its sequence, the mature protein secreted from yeast showed no bacteriolytic activity. A significant decrease (54%, P < or = 0.001) in the number of sperm bound to zona-free hamster eggs was observed in the presence of antisera to recombinant SLLP1. SLLP1 mRNA (size, approximately 1 kb) appeared to be expressed only in the testis and in the Burkitt lymphoma Raji cell line. The gene SPACA3 encodes SLLP1 and contains five exons at locus 17q11.2. Because of its typical c lysozyme-like sequence, genomic organization, conservation of putative substrate-binding sites even in the absence of catalytic residues, and localization in the acrosomal matrix, we hypothesize that, after acrosome reaction, SLLP1 could be a potential receptor for the egg oligosaccharide residue N-acetylglucosamine, which is present in the extracellular matrix over the egg plasma membrane, within the perivitelline space, pores of zona pellucida, and cumulus layers.
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PMID:SLLP1, a unique, intra-acrosomal, non-bacteriolytic, c lysozyme-like protein of human spermatozoa. 1260 93


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