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)

Using radioiodinated, photoactivable, reducible cross-linker conjugated bacterial endotoxic lipopolysaccharide (125I-ASD-LPS), we have demonstrated that LPS selectively binds to the S2 subunit of pertussis toxin (PT). Since LPS also interacts with the S2 subunit of the B-oligomer of the toxin, the binding of LPS to PT is not A-protomer (S1 subunit) dependent. The binding can be inhibited with native underivatized LPS and with purified lipid A, suggesting that the binding is mediated through the lipid A moiety of the LPS molecule. The binding of PT to LPS can be inhibited by bovine fetuin glycoprotein. Since PT has been demonstrated to interact specifically with N-linked oligosaccharide side chains of fetuin, the interaction of LPS with the S2 subunit of PT may involve carbohydrate-dependent interactions of the disaccharide backbone of lipid A with S2. Additional studies have documented that LPS binding to PT may be competitively inhibited by lysozyme but not by polymyxin B. Sequence analysis has allowed identification of a high degree of amino acid sequence similarity between the S2 subunit of PT and hen egg white lysozyme at the N-terminal 80-residue regions. Shared N-terminal sequence similarity between lysozyme, PT-S2, and a third LPS-binding protein alpha-lactalbumin allows tentative identification of a second family of LPS binding proteins.
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PMID:Lipopolysaccharide interaction with S2 subunit of pertussis toxin. 841 48

New, never-worn, individual hydrophilic contact lenses were incubated in an artificial tear solution (containing lysozyme, albumin, lactoferrin, and glycoprotein) for 24 hours at 37 degrees C with constant stirring. These lenses were then cleaned following the manufacturer's instructions with one of six commercial cleaning systems: AOSEPT, CONSEPT, Oxysept, ReNu, Opti-Free and thermal disinfection in conjunction with the Allergan Enzymatic Contact Lens Cleaner. The protein remaining on each lens after cleaning was removed and then quantified by the Bio-Rad Protein Assay. High resolution gel electrophoresis was used to assess the individual protein profile patterns. We found that only one-third to one-half of the protein deposited on a lens is removed by the above cleaning systems. Of the proteins in the artificial tear solution only lysozyme is removed by cleaning, while lactoferrin, albumin, and glycoprotein tend to remain on the lens. Since many of the complications experienced by contact lens wearers are thought to be related to protein deposits on their lenses, our results suggest the need for more effective contact lens cleaning solutions.
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PMID:The efficacy of hydrophilic contact lens cleaning systems in removing protein deposits. 845 52

The large molecular size of N-glycosylated lysozyme with a polymannose chain was predominantly expressed in the yeast carrying the lysozyme expression plasmid in 9-fold greater secretion compared with the wild type. Complementary DNA encoding hen egg white lysozyme was subjected to site-directed mutagenesis to obtain the Asn-X-Ser/Thr sequence that is the signal for asparagine-linked (N-linked) glycosylation. At positions 49, 67, 70, and 103, the signal for N-linked glycosylation was created. Only the mutant lysozyme whose glycine 49 was substituted with asparagine was expressed in the two types of glycosylated forms, a small oligomannose chain (Man18GlcNAc2)-linked form and a large polymannose chain (Man310GlcNAc2)-linked form, whereas other mutants were not glycosylated. The secreted amount of polymannosyl lysozyme was much higher than that of the oligomannosyl lysozyme. Both types of glycosylated lysozymes were susceptible to endo-beta-N-acetylglucosaminidase cleavage of their carbohydrate chains. The average molecular masses of oligomannosyl and polymannosyl lysozymes were 18 and 71 kDa, respectively. The length of the polymannose chain was found to be 200-350 residues/molecule of lysozyme according to the estimation of the molecular mass distribution by low angle laser light scattering measurements. The protein conformation estimated by CD analysis was completely conserved in these glycosylated lysozymes. The enzymatic activities of oligomannosyl and polymannosyl lysozymes were 100 and 91%, respectively, of wild-type protein when glycol chitin was used as a substrate. In addition, the polymannosyl lysozyme revealed remarkable heat stability in that no coagulation was observed under conditions in which the wild-type lysozyme coagulated. Thus, this novel glycoprotein can be used as a reporter in studies of the processing and sorting of glycoproteins and as a model of the expression of foreign genes in yeast for the construction of stable enzymes.
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PMID:Hyperglycosylation of hen egg white lysozyme in yeast. 850 5

The efficiency of membrane fusion between reconstituted Sendai viral envelopes containing only the fusion protein (F-virosomes) and the plasma membrane of mouse teratocarcinoma cells (F9) in culture was assessed using an assay based on the relief of self-quenching of a lipid probe incorporated in the F-virosomes. The potential of F-virosomes was also evaluated for a targeted cytosolic delivery of lysozyme to F9 cells. [125I]Lysozyme entrapped into F-virosomes was taken to examine its fusion-mediated transfer to the F9 cells. Target specificity of the F-virosomes was confirmed by the interaction between the terminal Le(x) moiety (Gal beta 1-->4(Fuc alpha 1-->3)GlcNAc) of F protein and the Le(x) determinant on the membrane of F9 cells. Incubation of the loaded F-virosomes with cells led to fusion-mediated delivery, as inferred from the ability of cells to internalize lysozyme in the presence of azide (a potent inhibitor of endocytosis). These results suggest that carbohydrate-carbohydrate interaction is strong enough for target cell recognition followed by phospholipid bilayer melding induced by fusion glycoprotein of Sendai virus.
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PMID:F protein induced fusion of Sendai viral envelopes with mouse teratocarcinoma cells through Le(x)-Le(x) interaction. 870 9

To examine the transport of the single subunits of the glycoprotein complex gp80 (clusterin, apolipoprotein J), a marker protein for apical exocytosis and main secretory product of Madin-Darby canine kidney (MDCK) cells, several mutant cDNAs were constructed and expressed in the fibroblastic baby hamster kidney (BHK-21) cell line. In the absence of the second subunit the mutant proteins formed disulfide-linked homodimeric complexes. In the homodimeric form lys-gp45, a lysozyme-tagged mutant representing the C-terminal subunit, acquired competence for transport to the cell surface. Biogenesis and transport of this hybrid protein were also examined in stably transfected MDCK cells. In these cells which express both the endogenous gene and the mutant cDNA lys-gp45 was linked via disulfide bonds to the gp80 complex. These heterooligomeric complexes were secreted predominantly at the apical cell surface. Thus, oligomerization regardless of whether it resulted in homodimeric or heterooligomeric complexes conveyed transport competence to the mutant protein.
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PMID:Oligomerization supports transport of a mutant secretory protein out of the endoplasmic reticulum. 890 10

Human saliva is secreted by the three pairs of major salivary glands (parotid, submandibular, and sublingual), and numerous minor ones, e.g. labial, buccal and (glosso)palatine glands. Using individually adapted collection devices, sublingual, submandibular, parotid and palatine secretions of five individuals were collected and analyzed. Electrophoretic analysis revealed that each type of saliva possesses characteristic features, despite interindividual variations. Parotid salivas are characterized by intensely staining amylase and proline-rich protein bands, but contain minute amounts of cystatins, lysozyme and the extra-parotid glycoprotein. Sublingual salivas are characterized by high concentrations of both types of salivary mucins, MG1 and MG2, and contain relatively high levels of lysozyme. Submandibular salivas contain highest concentration of salivary cystatin S. Palatine secretions contain high molecular weight mucins and a relatively high amylase concentration.
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PMID:Human glandular salivas: their separate collection and analysis. 893 May 81

In a previous paper we reported the presence of components in human tear fluid that block the interaction of proteins with plastic surfaces, interfering with tear protein ELISA and proposed the term coating inhibiting activity. The purpose of the study presented here was to further analyse these components. Coating inhibitory activity in human reflex tears was analysed by lectin affinity chromatography, using the agarose bound lectin Artocarpus integrifolia agglutinin (Jacalin), gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), blotting and Jacalin staining. For coating inhibitory activity assay in experimental tear samples, the binding of the protein Avidin-conjugated horseradish peroxidase to the polystyrene surface of ELISA micro-titer plate wells, preincubated with the experimental tear samples was measured. In addition, tears were incubated with scrapings of the ELISA plates used in the assay and with six different types of contact lenses (two rigid gas permeable and four hydrogel soft contact lenses) for analysis of adsorbed components. Lectin affinity chromatography of tears yielded a Jacalin-binding and a non-Jacalin-binding preparation, both exhibiting coating inhibitory activity but representing chemically different preparations as observed by SDS-PAGE. After performing gel filtration, coating inhibitory activity eluted with similar retention in both preparations. In fractions exhibiting activity, tear proteins of low molecular weight (< 40 kDa) were detected. Among these, two Jacalin-binding glycoproteins were detected; a major component of approximately 28 kDa and a somewhat smaller minor component. All low molecular weight components were also detected on the scrapings, incubated with tears. The possibility that coating inhibitory activity in tears might reside in a component of larger molecular size can however not be excluded. The human tear proteins secretory Immunoglobulin A, lactoferrin and lysozyme are not involved in coating inhibition. On one of the two rigid gas permeable contact lenses incubated with the tears, the 28 kDa glycoprotein was detected. From the data obtained in our study we conclude that coating inhibitory activity in tears seems to be associated with multiple components of low molecular weight.
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PMID:Analysis of human tear fluid components, inhibiting protein adhesion to plastic surfaces. 894 5

1. Studies were directed at determining whether hepatocytes, isolated from female Sprague-Dawley rats, facilitate the uptake of protein-bound long-chain fatty acids. We postulated one form of facilitated uptake may occur through an ionic interaction between the protein-ligand complex and the cell surface. These interactions are expected to supply additional ligand to the cell for uptake. 2. The clearance rate of [3H]-palmitate in the presence of alpha 1-acid-glycoprotein (pI = 2.7), albumin (pI = 4.9) and lysozyme (pI = 11.0) was investigated. Palmitate uptake was determined in the presence of protein concentrations that resulted in similar unbound ligand fractions (= 0.03). The experimental clearance rates were compared to the theoretical predictions based upon the diffusion-reaction model. 3. By use of our experimentally determined equilibrium binding and dissociation rate constants for the various protein-palmitate complexes, the diffusion-reaction model predicted clearance rates were 4.9 microliters s-1/10(6) cells, 4.8 microliters s-1/10(6) cells and 5.5 microliters s-1/10(6) cells for alpha 1-acid-glycoprotein, albumin and lysozyme, respectively; whereas the measured hepatocyte palmitate clearance rates were 1.2 +/- 0.1 microliters s-1/10(6) cells, 2.3 +/- 0.3 microliters s-1/10(6) cells and 7.1 +/- 0.7 microliters s-1/10(6), respectively. 4. Hepatocyte palmitate clearance was significantly faster (P < 0.01) in the presence of lysozyme than albumin which was significantly faster than alpha 1-acid-glycoprotein (P < 0.01). The marked difference in clearance rates could not be explained by considering differences in solution viscosity. 5. Our results are consistent with the notion that ionic interactions between protein-ligand complexes and the cell surface facilitate the ligand uptake by decreasing the diffusional distance of the unbound ligand and/or by facilitating the protein-ligand dissociation rate.
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PMID:Effect of binding protein surface charge on palmitate uptake by hepatocyte suspensions. 910 95

To understand the changes in protein expression associated with various physiological states as well as the development of pathological eye disease, we have begun to map the protein components of normal human reflex tears. An analytical reference map of normal human reflex tears was created using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) with pH 3.5-10 immobilized pH gradients (IPGs). Micropreparatively loaded gels were transferred to polyvinylidene difluoride (PVDF) and analysed by a combination of N-terminal sequence tagging and amino acid compositional analysis. Thirty spots were sequence tagged, resulting in identification of six different proteins (lipocalin, lysozyme, lactotransferrin, zinc-alpha-2 glycoprotein, cystatin S, cystatin SN) that matched to entries in the SWISS-PROT database. A group of N-terminally blocked proteins was clearly identified from SWISS-PROT by amino acid analysis, isoelectric point (pI) and molecular weight (Mr). A number of highly expressed protein components remain unidentified despite being subjected to amino acid analysis and Edman sequencing. A majority of the abundant proteins showed varying degrees of charge heterogeneity attributed to post-translational processing such as glycosylation and N-terminal truncation. We have identified a previously undescribed protein that we have named lacryglobin. This protein displays strong homology with mammaglobin, a protein overexpressed in breast cancer. The discovery of this homologue in tears offers the potential for disease diagnosis by screening tear fluid proteins.
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PMID:Establishment of the human reflex tear two-dimensional polyacrylamide gel electrophoresis reference map: new proteins of potential diagnostic value. 950 14

The sex-inducing pheromone of the multicellular green alga Volvox carteri is a glycoprotein that triggers development of males and females at a concentration <10(-16) M. By differential screening of a cDNA library, two novel genes were identified that are transcribed under the control of this pheromone. Unexpectedly, one gene product was characterized as a lysozyme/chitinase, and the other gene product was shown to encode a polypeptide with a striking modular composition. This polypeptide has a cysteine protease domain separated by an extensin-like module from three repeats of a chitin binding domain. In higher plants, similar protein families are known to play an important role in defense against fungi. Indeed, we found that the same set of genes triggered by the sexual pheromone was also inducible in V. carteri by wounding.
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PMID:The sex-inducing pheromone and wounding trigger the same set of genes in the multicellular green alga Volvox. 959 36


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