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)

Hen egg-white lysozyme (EC 3.2.1.17) was carboxymethylated with iodoacetic acid and the individual products of various degree of modification were isolated by column chromatography on Amberlite CG-50. Peptide mapping of the products obtained reveals that His-15, Lys-1, -33, -96 (or -97) residues are blocked; the Lys-13 and -116 residues are unmodified. Salt activation of the carboxymethylated derivatives is facilitated with the increase of the number of modified groups; this fact is consistent with the increased lytic activity and affinity to substrate of the derivatives at lowered ionic strength.
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PMID:[Preparation and characteristics of carboxymethylated lysozyme derivatives]. 69 4

Bombesin, gastrin-related peptide (GRP), and related peptides sharing the common carboxyterminal sequence stimulate lactoferrin (serous cell marker) and glycoconjugate (mucous cell and goblet cell marker) release from human nasal mucosal explants in vitro. In vivo, GRP released from trigeminal sensory nerves may act upon GRP-bombesin binding sites on respiratory epithelial cells and submucosal glands. To determine whether GRP-bombesin can stimulate nasal secretion in vivo, bombesin was administered to eight normal subjects by unilateral, topical administration. Secretions from both nostrils were collected for measurement of total protein, lysozyme, hexose-containing glycoconjugates, and albumin (marker of vascular permeability). Baseline secretions contained 72.0 +/- 17.3 micrograms/ml of total protein, 14 +/- 2 micrograms/ml of lysozyme, 113 +/- 44 micrograms/ml of hexose-containing glycoconjugates, and 7.8 +/- 3.4 micrograms/ml of albumin. Hexose-containing glycoconjugate secretion was significantly increased after 1 nmol (385 +/- 63 micrograms/ml, P less than 0.001 by analysis of variance), 10, 100, and 1,000 nmol of bombesin, but the secretion was not dose dependent. Significant lysozyme (24 +/- 3 micrograms/ml, P less than 0.05) and total protein (155 +/- 23 micrograms/ml, P less than 0.01) secretion occurred after 1,000 nmol. No statistically significant changes in albumin secretion occurred at any dose. Saline had no significant effects on secretion. Therefore, bombesin stimulated secretion from submucosal glands and possibly epithelial cells in the human nose without affecting vascular permeability.
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PMID:Bombesin stimulates human nasal mucous and serous cell secretion in vivo. 173 81

The lysozyme from bacteriophage T4 is being used as a model system to determine the roles of individual amino acids in the folding and stability of a typical globular protein. Such studies can provide quantitative information on the contributions made by different types of interactions including hydrogen bonds, hydrophobic interactions, salt bridges and disulphide bridges. To determine the contribution of long-range electrostatic interactions a combination of charge-change mutations was used to reduce the overall formal charge on T4 lysozyme at neutral pH from +9 to +1 units. Such changes in charge were found to have little effect on the stability of the molecule. Salt bridges engineered on the surface of the protein also were found to contribute little to stability. In contrast, the introduction of acidic groups designed to interact with the partial positive charges at the N-termini of alpha-helices consistently increased the stability of the protein. It is argued that this difference between electrostatic salt-bridge interactions and electrostatic 'helix-dipole' interactions lies in the entropic cost of bringing together the interacting partners. In an attempt to simplify the folding problem, and also to further investigate the helix propensity of different amino acids, a series of alanines was introduced within an alpha-helix of T4 lysozyme. The resultant protein not only folds normally but is also more stable than the wild-type enzyme, adding further support to recent evidence that alanine is a helix-favouring amino acid.
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PMID:Structural and genetic analysis of electrostatic and other interactions in bacteriophage T4 lysozyme. 181 96

Inoculation of live Escherichia coli into tsetse flies, Glossina morsitans morsitans, stimulated a higher antibacterial immune response in females than in males. It increased with age in females from emergence to approximately 2 weeks and thereafter declined. In males, there was also a significant decrease in immune response with aging. Inoculation of killed bacteria failed to stimulate antibacterial activity but stimulated a lysozyme response which was weaker than that stimulated by live bacteria. No antibacterial activity was present in the hemolymph of larvae from immunized pregnant tsetse. Inoculation of live Trypanosoma brucei brucei and T. congolense failed to induce production of antibacterial activity and lysozyme. Furthermore, tsetse inoculated with or naturally infected with T. b. brucei and T. congolense failed to show any evidence of immunosuppression when challenged with live E. coli. Various species of live bacteria stimulated different levels of antibacterial factors, with Enterobacter cloacae stimulating the highest level of antibacterial activity and E. coli the highest level of lysozyme. Saline in which certain species of bacteria and T. b. brucei were incubated inactivated tsetse immune hemolymph.
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PMID:The humoral defense system in tsetse: differences in response due to age, sex and antigen types. 338 55

Salt solutions and charged detergents are efficient solubilizing agents for ovovitelline membrane lysozyme. Reassociation experiments with chemically modified lysozymes indicate that positively charged amino acid residues of lysozyme (the epsilon-amino group of lysine and the guanidino group of arginine) are involved in the interaction with other proteins of the vitelline membrane. Exogenous proteins are adsorbed to lysozyme-free vitelline membranes, only if they have a high pI, comparable to that of lysozyme. It is concluded that the lysozyme-ovovitelline membrane interaction is predominantly ionic. An ovomucin-lysozyme complex is postulated as the major component of the outer layer of the membrane.
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PMID:Mode of interaction between lysozyme and the other proteins of the hen's egg vitelline membrane. 374 71

The use of different assay conditions has complicated the evaluation of studies relating salivary lysozyme levels to oral or systemic disease. The purpose of this study was to compare values obtained for lysozyme activity in mixed saliva of 104 healthy subjects by using two assay techniques and four variations in sample preparation. Lysozyme activity was assayed by the turbidimetric and lysoplate methods with human colostrum lysozyme as the standard. Lysozyme activity in saliva samples made 0.5 M with respect to NaCl was compared with that in untreated samples with and without centrifugation. Mean values for lysozyme concentration in centrifuged saliva were 2.2 micrograms/ml with the turbidimetric assay and 5.9 micrograms/ml with the lysoplate assay. In samples which were salt treated before centrifugation, mean concentrations increased to 17.3 and 72.9 micrograms/ml, respectively. The results for uncentrifuged saliva were four to five times higher than the results for centrifuged saliva in each of the assay systems. Salt treatment without centrifugation produced values comparable to those obtained with centrifugation. The addition of salt to human colostrum or hen egg white lysozyme generally resulted in a 20 to 25% increase in expressed activity. These results indicate that the measurement of lysozyme in the supernatant of centrifuged saliva is of questionable value, most of the lysozyme in whole saliva is inactive and may be activated by markedly increasing the ionic strength, and values for lysozyme activity in whole saliva are much greater in the lysoplate assay than in the turbidimetric assay when the same standard is used.
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PMID:Factors influencing measurement of human salivary lysozyme in lysoplate and turbidimetric assays. 378 60

Suspensions of enterococci were treated with lysozyme in the presence of osmotic stabilizers. The resulting osmotically fragile bodies prepared from Streptococcus faecium strain F24 and S. faecalis strain E1 gave rise to L-forms under optimal osmotic and nutritional conditions for treatment and subsequent growth. The most critical component of the growth medium, to obtain maximum yields, was the nature and concentration of the added salt. The two most effective salts were sodium chloride and ammonium chloride in the range of 2 to 3% (w/v) added to a suitable agar base. Ammonium chloride was more versatile, because it could be used with either sucrose or polyethylene glycol 4000 as the osmotic stabilizer for preparation and dilution of the osmotically fragile bodies. Sodium chloride would not consistently support growth of S. faecium F24 as L-forms when polyethylene glycol 4000 was used as the osmotic stabilizer during lysozyme treatment. Time-course studies of concurrent cell wall removal and L-form induction suggested that maximal induction required only cell wall damage rather than complete wall removal. This method for induction of L-forms from a suspension of enterococci is a significant improvement over other presently known methods.
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PMID:Induction of enterococcal L-forms by the action of lysozyme. 499 Aug 48

Sucrose density gradient centrifugation of cell envelopes of chemotrophically grown cells of Rhodopseudomonas capsulata St. Louis (= ATCC 23782) resulted in the separation of a cytoplasmic membrane from a cell wall fraction (buoyant densities, 1.139 and 1.215 g/cm3, respectively). The cell wall fractions (untreated or Triton extracted) contained peptidoglycan- and lipopolysaccharide-specific components. Their neutral sugar content, mainly rhamnose and galactose, was high (250 and 100 micrograms/mg [dry weight] of material) due to a non-lipopolysaccharide polymer. The fatty acid content was low (less than or equal to 60 micrograms/mg [dry weight] of material), and half of it was contributed by lipopolysaccharide (3-OH-C10:0, C12:1, and 3-oxo-C14:0). The predominant other fatty acid was C18:1. An outer membrane fraction, obtained by lysozyme treatment of the Triton-extracted cell wall, showed essentially the same chemical composition except for almost complete removal of peptidoglycan. Saline extraction (0.9% NaCl, 37 degrees C, 2 h) removed a lipopolysaccharide-protein(-phospholipid?) complex from whole cells of R. capsulata St. Louis. The polypeptide patterns of the cell wall and outer membrane as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis comprised 20 to 25 different polypeptides (most of them very faint) and were dominated by a single, heat-modifiable major protein (Mr 69,000 after solubilization below 60 degrees C; Mr 33,000 at temperatures above 70 degrees C).
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PMID:Characterization of the cell wall and outer membrane of Rhodopseudomonas capsulata. 673 79

Salt treatment of the cytoplasmic estradiol-receptor complex from chick oviduct induces a strong affinity of the complex for DNA-cellulose and phenyl-sepharose. This process is called activation. Binding to heparin- and lysozyme-sepharose is also observed with the untreated complex. But, the salt treatment, additional binding of the complex to these adsorbents is seen. The increased ability of the complex to bind to polyanions and polycations is destroyed by mild trypsination. The binding to the hydrophobic adsorbent is not affected by this treatment. Neither a change of the sedimentation constant nor of the size of the receptor protein is observed after salt treatment in the cold. After binding of the salt-activated estradiol-receptor complex to DNA-cellulose in the cold, an increase of its sedimentation constant and its size, as measured by density-gradient centrifugation and agarose gel chromatography, resp., becomes apparent. A similar phenomenon is observed after binding to DEAE-cellulose and to some extent after binding to heparin-sepharose. The nuclear complex seems to have the same sedimentation constant as the cytoplasmic complex eluted from DNA-cellulose. The sedimentation constant of the nuclear complex is not changed after DNA-cellulose chromatography. The cytoplasmic progesterone-receptor complex from the same tissue, i.e. the oviduct, does not show any change of size. Thus the well-known process of transformation can now be separated into 2 steps. (1) Activation of the estradiol-receptor complex for its binding to various adsorbents in vitro and probably to its acceptor site(s) in vivo. (2) Increase of receptor size. This second step seems to be a special property of the estradiol-receptor complex. Its physiological significance is unclear.
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PMID:Transformation of the estrogen-receptor complex from chick oviduct in 2 steps. 720 34

Aqueous two-phase systems composed of ethylene oxide/propylene oxide random co-polymers, EO30/PO70 or Ucon (EO50/PO50), in the top phase and dextran T500 in the bottom phase, have been studied. The cloud point diagram for EO30/PO70 in water solution was determined. EO30/PO70 has a cloud point of 32 degrees C at a concentration of 10% (w/w). The phase diagram for the system EO30/PO70-dextran T500-water was determined. Salt effects have been studied on the partitioning of two model proteins, bovine serum albumin and hen egg white lysozyme, in EO30/PO70-dextran and Ucon-dextran systems. Ions with different hydrophobicity, i.e., with different position in the Hofmeister or lyotropic series, were investigated with reference to their effect on protein partition. The counterion hydrophobicity was shown to have a strong influence on the partitioning of BSA and lysozyme. Most extreme partitioning was obtained with hydrophobic (chaotropic) ions like CIO4- and I-. A comparison of protein partitioning between PEG-dextran and EO30/PO70-dextran has been done. A more extreme protein partitioning was obtained in the EO30/PO70-dextran containing system. Temperature-induced phase separation was studied with EO30/PO70 at 45 degrees C. Both BSA and lysozyme were completely partitioned to the water phase formed above the cloud point of EO30/PO70. Model calculations, based on Flory-Huggins theory of polymer solutions, have been done which could reproduce the salt effect on the protein partitioning in aqueous-two phase system.
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PMID:Effects of ions on partitioning of serum albumin and lysozyme in aqueous two-phase systems containing ethylene oxide/propylene oxide co-polymers. 876 33


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