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)

The effects of some synthetic polyribonucleotides on induction of differentiation of mouse myeloid leukemic M1 cells were examined. Poly(I) was found to be a potent inducer; on treatment with 100--200 microgram/ml of poly(I) for 2--4 days, M1 cells differentiated into cells resembling macrophages and granulocytes and developed phagocytosis and locomotive activities, Fc receptors and lysozyme activity. Poly(C) was less effective than poly(I) for induction of phagocytic activity, while the other single-stranded RNAs, poly(U) and poly(A), had no effect. Double-stranded RNAs, such as poly(I) . poly(C) and poly(A) . poly(U), were cytotoxic to M1 cells, and differentiation of the cells could not be detected even at the highest tolerable concentrations of these double-stranded RNAs.
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PMID:Induction by synthetic polyribonucleotide poly(I) of differentiation of cultured mouse myeloid leukemic cells. 28 41

Diabetes in the non-obese diabetic (NOD) mouse is a multigenic autoimmune disease and is possibly controlled by three recessive loci, including one that is linked to the major histocompatibility complex (MHC). The first external domain of the Class II MHC I-A beta chain in these mice is unique and has been suggested as being responsible for autoimmunity. The I-A alpha chain in these mice is I-A alpha d, and they lack the expression of I-E molecules. We have investigated immune responses to various Ir gene control antigens in NOD mice to determine the influence of the NOD Ia and particularly the I-A beta chain. We find that sheep insulin is highly immunogenic while other insulins are weakly immunogenic in these mice. Hen egg lysozyme, pigeon cytochrome C and the synthetic polypeptide Poly 18, Poly EYK(EYA)5 antigen produce good antibody responses. Apart from H-2d, NOD are the only mice where Poly 18 antigen is immunogenic. In these mice Poly 18 induced good T-cell proliferative response, which was inhibited by anti-Ia antibody, and the mice were able to respond to tyrosine-containing polypeptide Poly EYA but not to the phenylalanine-containing antigen Poly EFA. We also found that synthetic peptide 48-60 of the NOD I-A beta chain is highly immunogenic in syngeneic NOD mice both for T cells and B cells. Using an I-A beta chain-specific monoclonal antibody, we are able to prevent induction of diabetes when the antibody was administrated in prediabetic, young mice. Our results suggest that the immune response to various antigens and autoimmune diabetes in NOD mice is directly influenced by the I-A beta chain.
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PMID:Role of the first external domain of I-A beta chain in immune responses and diabetes in non-obese diabetic (NOD) mice. 170

The mechanism of reaction of proteins with 3-hydroxyanthranilic acid (3OHA) under oxidizing conditions has been examined. A range of proteins were found to tan when exposed to oxidized 3OHA. One exception was lysozyme which tanned only after being denatured by reduction and carboxymethylation. Chemical modification experiments using bovine serum albumin (BSA) suggested that lysine was the primary site of reaction in 3OHA-mediated protein tanning. This reactivity of 3OHA toward lysine was confirmed by autoxidizing 3OHA in the presence of amino acid homopolymers. The rate of modification of both BSA and polylysine was pH dependent. At neutral pH, a component of the coloration of the protein was found to be due to the formation of a lysyl-p-quinone adduct. Other products appear to arise through addition to the 3OHA quinone imine. Poly-(Glu,Lys) was tanned by 3OHA at a greatly reduced rate, suggesting that electrostatic interactions may influence the reaction with lysine residues and may provide an explanation for the lack of tanning of lysozyme. Despite the reaction between 3OHA and lysine, amino acid analysis revealed little quantitative change in the lysine content of proteins even after exposure to 3OHA for a period of 24 h. These results support the proposal that reaction with lysine residues is the major route of protein tanning by 3-hydroxyanthranilic acid.
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PMID:Modification of proteins by 3-hydroxyanthranilic acid: the role of lysine residues. 192 12

Polycationic polymers have been noted for their effects in promoting cell adhesion to various surfaces, but previous studies have failed to describe a mechanism dealing with this type of adhesion. In the present study, three polycationic polymers (chitosan, poly-L-lysine, and lysozyme) were tested for their effects on microbial hydrophobicity, as determined by adhesion to hydrocarbon and polystyrene. Test strains (Escherichia coli, Candida albicans, and a nonhydrophobic mutant, MR-481, derived from Acinetobacter calcoaceticus RAG-1) were vortexed with hexadecane in the presence of the various polycations, and the extent of adhesion was measured turbidimetrically. Adhesion of all three test strains rose from near zero values to over 90% in the presence of low concentrations of chitosan (125 to 250 micrograms/ml). Adhesion occurred by adsorption of chitosan directly to the cell surface, since E. coli cells preincubated in the presence of the polymer were highly adherent, whereas hexadecane droplets pretreated with chitosan were subsequently unable to bind untreated cells. Inorganic cations (Na+, Mg2+) inhibited the chitosan-mediated adhesion of E. coli to hexadecane, presumably by interfering with the electrostatic interactions responsible for adsorption of the polymer to the bacterial surface. Chitosan similarly promoted E. coli adhesion to polystyrene at concentrations slightly higher than those which mediated adhesion to hexadecane. Poly-L-lysine also promoted microbial adhesion to hexadecane, although at concentrations somewhat higher than those observed for chitosan. In order to study the effect of the cationic protein lysozyme, adhesion was studied at 0 degree C (to prevent enzymatic activity), using n-octane as the test hydrocarbon. Adhesion of E. coli increased by 70% in the presence of 80 micrograms of lysozyme per ml. When the negatively charged carboxylate residues on the E. coli cell surface were substituted for positively charged ammonium groups, the resulting cells became highly hydrophobic, even in the absence of polycations. The observed "hydrophobicity" of the microbial cells in the presence of polycations is thus probably due to a loss of surface electronegativity. The data suggest that enhancement of hydrophobicity by polycationic polymers is a general phenomenon.
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PMID:Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers. 221 2

Yeast cells, Candida utilis, in water suspension and in the absence of electrolytes were found to be very sensitive to several proteins of moderate size, including ribonuclease, protamine, lysozyme, bovine serum albumin, cytochrome c, and myoglobin. Viability ceases rapidly, and ultraviolet-absorbing compounds (260 mmu) and the amino acid pool are released into the medium. The ultraviolet-absorbing material appears to be the nucleotide and coenzyme fraction usually extracted by 0.2 n perchloric acid at low temperature. The ribonucleic acid fraction remains in the cell ghosts and can be released by ribonuclease. The enzymatic properties of some of these proteins have no relation to their damaging effect on the cell membrane. Poly-l-lysine shows the same activity.
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PMID:Effect of some proteins on the yeast cell membrane. 429 20

Protamine sulfate reversibly inhibits serum-induced mitogenic stimulation of several nontransformed and neoplastic cell types in vitro. Fifty percent inhibition was induced by approximately 120-150 micrograms protamine sulfate/ml. Cells were affected directly, and inhibition depended on the duration of cell exposure. Heparin, chondroitin sulfate, heparan sulfate, and dextran sulfate neutralized protamine sulfate effects during the early stages of treatment. Nontransformed cells [bovine aortic endothelial cells, adult human gingival fibroblasts (strains 423 and 1101), fetal rat skin (strain 921-K) and muscle fibroblasts] required longer exposure to induce inhibition than did neoplastic cells [rat 3-methylcholanthrene-induced fibrosarcoma cell lines (MCA-6 and MCA-9), a macrophage-like cell line (NCTC-3749), Walker 256 rat carcinoma cells (ATCC-CCL-38), rat Morris hepatoma cells (ATCC-CCL-144), murine melanoma cells (B16), and rat bladder squamous cell carcinoma cells (804-G)]. Other polycationic compounds, including histone type VIII-S, poly-L-lysine, poly-L-arginine, and protamine (free base), were also effective inhibitors, whereas the basic proteins cytochrome c and lysozyme had no effect. Poly-L-histidine, poly-L-glutamic acid, poly-L-aspartic acid, and dextran blue also had no inhibitory effect.
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PMID:Protamine sulfate inhibition of serum-induced mitogenic responses: differential effects on normal and neoplastic cells. 621 Mar 90

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

Histidine, histamine and polymyxin B affinity sorbents were employed for the removal of Escherichia coli-derived endotoxins. Their effectiveness was compared with those of poly-L-lysine-Sepharose and DEAE-Sepharose. All sorbents reduced the concentration of endotoxins from an E. coli culture filtrate to tolerable levels. However, their effectiveness was not higher than that of the anion exchanger, which displayed clearance rates of up to 15,000. Endotoxin removal from protein solutions depended on the net charge of the desired protein. Lysozyme as a model for positively charged proteins enhanced endotoxin removal. In contrast, only low initial contamination levels (< 34 EU/ml) were reduced to tolerable levels from bovine serum albumin (BSA) as the negatively charged protein model owing to competition of BSA and endotoxins for adsorption sites. Hence also a low BSA recovery was observed after the treatment whereas the lysozyme recovery was almost 100%. At pH values below the isoelectric point of BSA, endotoxin removal was also more effective. The best conditions for the decontamination were found at neutral pH and low ionic strength (< or = 20 mM phosphate). Ionic forces between ligands and endotoxins are dominant at this ionic strength; hydrophobic interactions are not very effective. Hence the selectivities of all sorbents towards endotoxins are not exceptionally high. DEAE-anion exchangers are the most suitable sorbents for the removal of endotoxins from solutions accommodating positively charged proteins owing to their low cost and high capacity. Poly-L-lysine-Sepharose was most effective for the removal of small amounts of endotoxins from solutions of negatively charged proteins. The "affinity ligands" histamine, histidine and polymyxin B were effective for the removal of endotoxins from E. coli filtrate; however, their effectiveness decreased dramatically in the presence of BSA and it was lower than for poly-L-lysine- and DEAE-Sepharose in the presence of lysozyme.
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PMID:Removal of endotoxins by affinity sorbents. 749 97

It has become a common practice to supplement human milk with a variety of additives to improve the nutritive content of the feeding for the premature infant. Twenty-two freshly frozen human milk samples were measured for lysozyme activity, total IgA, and specific IgA to Escherichia coli serotypes 01, 04, and 06. One mL aliquots were mixed with the following: 1 mL of Similac, Similac Special Care, Enfamil, Enfamil Premature Formula, and sterile water; 33 mL of Poly-Vi-Sol, 33 mg of Moducal, and 38 mg of breast-milk fortifier, and then reanalyzed. Significant decreases (41% to 74%) in lysozyme activity were seen with the addition of all formulas; breast-milk fortifier reduced activity by 19%, while no differences were seen with Moducal, sterile water, or Poly-Vi-Sol. No differences were seen in total IgA content, but some decreases were seen in specific IgA to E. coli serotypes 04 and 06. E. coli growth was determined after 3 1/2 hours of incubation at 37 degrees C after mixing. All cow-milk formulas enhanced E. coli growth; soy formulas and other additives preserved inhibition of bacterial growth. Nutritional additives can impair anti-infective properties of human milk, and such interplay should be considered in the decision on the feeding regimen of premature infants.
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PMID:The effect of nutritional additives on anti-infective factors in human milk. 820 Jan 64

N-Acetyl-D-glucosaminylpyrophosphorylundecaprenol (GlcNAc-P-P-Und), an intermediate in the biosynthesis of the enterobacterial common antigen in E.coli and some O-antigen chains in gram-negative bacteria, is formed by the transfer of GlcNAc 1-P from UDP-GlcNAc to Und-P, analogous to the reaction forming GlcNAc-P-P-dolichol (GlcNAc-P-P-Dol) in mammalian cells. Since the microsomal enzyme from animal cells exhibits a strong preference for Dol-P, which contains a saturated alpha-isoprene unit, the polyisoprenyl phosphate specificity of the homologous bacterial enzyme was characterized. The enzyme remained bound to the membrane fraction when spheroplasts, formed by lysozyme-EDTA treatment, were lysed in hypotonic buffer. GlcNAc-P-P-Und synthase (GPT) activity was elevated in a strain of E.coli bearing the rfe gene, which encodes GPT on a multicopy plasmid, and virtually absent from rfe null mutants. GPT actively utilized fully unsaturated polyprenyl phosphate (Poly-P) substrates with maximal activity seen with (C55) Und-P, but was unable to utilize (C55)Dol-P. This substrate specificity contrasts with the microsomal GPT from pig brain, which actively utilized (C55)Dol-P, but not Und-P, as substrate. GPT activity bound to particulate fractions from three strains of bacilli also exhibited a strict preference for fully unsaturated Poly-P substrates. Unexpectedly, E.coli GPT activity cofractionated with the cytosolic marker enzyme, beta-galactosidase, and not the membrane-bound enzyme, D-lactate dehydrogenase, in cells disrupted in a French pressure cell. The properties and polyisoprenyl phosphate specificity of the soluble form of GPT were identical to the activity associated with the membrane preparations obtained from spheroplasts. The evolutionary and functional significance of the use of polyisoprenyl glycosyl carrier lipids with saturated alpha-isoprene units in eukaryotes remains uncertain.
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PMID:Polyisoprenyl phosphate specificity of UDP-GlcNAc:undecaprenyl phosphate N-acetylglucosaminyl 1-P transferase from E.coli. 913 38


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