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)

Rabbits homozygous at the Ab kappa chain allotypic locus (Ab4/Ab4 and Ab9/Ab9) were immunized with negatively and positively charged antigens. The negatively charged antigens were bovine serum serum albumin (BSA; pI = 4.9), ovalbumin (OV; pI = 4.9) and two synthetic polypeptides: copolymer L-glutamic acid L-tyrosine (abbreviated TG; pI = 4.8) and multichain poly (L-tyrosine: L-glutamic acid) poly D-alanine: poly L-lysine (poly L-lysine backbone) abbreviated (TG) --AL; pI = 4.8). The positively charged antigen was hen egg lysozyme (LYS; pI = 10.2). Homozygous Ab9 rabbits responding to negatively charged antigens made less antibody than did Ab4 homozygotes. In contrast, both groups of animals responded equally well to positively charged lysozyme. The relative electric charges of the antibodies were assessed by Sephadex A-50 chromatography. The charge distribution was found to depend on the charge of the eliciting antigen. The positively charged antibodies of Ab9/Ab9 rabbits were not nearly as positively charged as those raised in Ab4/Ab4 rabbits. The difference in average electric charges and in the range of these charges between Ig Ab4 and Ig Ab9 explain quantitative differences in antibody formation in response to negatively charged antigens and may be a contributing factor to the "pecking order", i.e. unequal phenotypic expression of light chain genes in Ab4/Ab9 heterozygotes.
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PMID:Allotype and charge-related differences in the immune response. 680 91

Proteins obtained from the surface of human teeth in vivo were solubilized in EDTA and subjected to gel permeation, ionic exchange chromatography and amino acid analysis. It was found that the main component was anionic and was eluted between albumin and lysozyme on Sepharose. It contained abundant amounts of serine, glycine and glutamic acid. A salivary phosphoprotein of similar amino acid composition has previously been purified.
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PMID:Gel filtration, ion exchange chromatography and chemical analysis of macromolecules present in acquired enamel pellicle (2-hour-pellicle). 695 33

The isolation and analysis of the Citrobacter O-serogroup Ci23Vi+ murein are described. The murein consists of alanine, glutamic acid, diaminopimelic acid (occurring in the molar ratio 1.5 : 1: 0.9), N-acetylmuramic acid and N-acetylglucosamine. Dialysable products resulting from the digestion of the Citrobacter O-serogroup Ci23Vi+ murein with egg white lysozyme resemble closely those obtained from the E. coli B murein.
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PMID:The murein of citrobacter O-serogroup Ci23 Vi+. 702 19

Reductive methylation of hen egg-white (HEW) lysozyme with [13C]formaldehyde and NaCNBH3 and subsequent 13C NMR spectroscopy reveal resonances for each of the mono- and dimethyl derivatives of the six lysyl epsilon-amino groups and the NH2 terminus. Each resonance has a unique chemical shift, pKa, and chemical shift change upon deprotonation. The assignment of the resonances arising from the N alpha,N-dimethyl and N alpha-monomethyl NH2 terminus has been made as have resonance assignments for the two lysyl residues which crystallographic studies indicate are involved in ion pair interactions (Imoto, T., Johnson, L. N., North, A. C. T., Phillips, D. C., and Rupley, J. A. (1972) in The Enzymes (Boyer, P. D., ed) 3rd Ed, Vol. 7, pp. 665-868, Academic Press, New York). One resonance, tentatively assigned to the lysine 1 (epsilon NH3+) which forms an ion pair with glutamic acid 7 (gamma COO-), has a highly perturbed chemical shift which shows a biphasic titration curve (N epsilon, N-dimethyl pKa values 10.0 and 2.6). A similar titration curve is observed for a N epsilon-monomethyl lysyl residue. The resonance for lysine 13 (epsilon NH3+), which forms an ion pair with the carboxyl terminus, leucine 129 (alpha COO-), has been assigned by removal of leucine 129 with carboxypeptidase whereupon only one pair of mono- and dimethyl lysyl resonances is greatly perturbed. The pKa of N epsilon,N-dimethyl lysine 13 is 9.3 in des-Arg-Leu-lysozyme in contrast to 9.8 for the intact enzyme. Thus, it appears that both of the intramolecular ion pairs predicted by x-ray crystallography exist in the solution structure of HEW lysozyme.
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PMID:Intramolecular interactions of amino groups in 13C reductively methylated hen egg-white lysozyme. 706 54

Three inducible bacteriolytic proteins, designated P7, P9A and P9B, from the hemolymph of immunized pupae of the giant silk moth Hyalophora cecropia have been purified using a two-step procedure with cation-exchange chromatography. Purified protein P7 has a molecular weight of 15000 and its amino acid composition shows a great similarity to that of the lysozyme from the wax moth Galleria mellonella. Moreover, heat stability, pH-rate profile and bacteriolytic specificity also indicate that protein P7 is a lysozyme. The other purified proteins, P9A and P9B, are highly potent against Escherichia coli and some other gram-negative bacteria. The amino acid compositions of proteins P9A and P9B are very similar, although the contents of glutamic acid and methionine were different. The molecular weights of these very basic proteins are around 7000. The P9 proteins are heat stable; their activities were retained after 30 min incubation at 100 degrees C. Both forms of protein P9 clearly differ from the lysozyme class of enzymes and they may represent a new type of bacteriolytic protein.
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PMID:Insect immunity. Purification and properties of three inducible bactericidal proteins from hemolymph of immunized pupae of Hyalophora cecropia. 734 Dec 34

Cytotoxicity of spermine in tissue culture was found previously. To neutralize this toxicity, the addition of various high molecular weight substances and others was attempted in this paper, e.g. lysozyme, N-acetyl-D-glucosamine, chondroitin sulfate, poly-L-glutamic acid, bovine serum fractions V and VI, fetal calf serum, methyl cellulose, carboxymethyl cellulose, polyvinylpyrrolidone and others. Into the culture of rat liver cells, strain RLC-10(2), simultaneous addition of other substances with spermine did not neutralize the toxicity. However, by the pretreatment of spermine with fetal calf serum or bovine serum albumin (fraction V) at 37 degrees C for 24 hr, the toxicity of spermine was markedly reduced. This was probably due to the denaturation of spermine caused by the pretreatment.
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PMID:Neutralization of cytotoxicity of spermine on the proliferation of rat liver cells in tissue culture. 738 32

Cadaverine was found to exist as a component of cell wall peptidoglycan of Selenomonas ruminantium, a strictly anaerobic bacterium. [14C]cadaverine added to the growth medium was incorporated into the cells, and about 70% of the total radioactivity incorporated was found in the peptidoglycan fraction. When the [14C]cadaverine-labeled peptidoglycan preparation was acid hydrolyzed, all of the 14C counts were recovered as cadaverine. The [14C]cadaverine-labeled peptidoglycan preparation was digested with lysozyme into three small fragments which were radioactive and were positive in ninhydrin reaction. One major spot, a compound of the fragments, was composed of alanine, glutamic acid, diaminopimelic acid, cadaverine, muramic acid, and glucosamine. One of the two amino groups of cadaverine was covalently linked to the peptidoglycan, and the other was free. The chemical composition of the peptidoglycan preparation of this strain was determined to be as follows: L-alanine-D-alanine-D-glutamic acid-meso-diaminopimelic acid-cadaverine-muramic acid-glucosamine (1.0:1.0:1.0:1.0:1.1:0.9:1.0).
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PMID:Cadaverine is covalently linked to peptidoglycan in Selenomonas ruminantium. 746 41

The 70-kDa soluble lytic transglycosylase (SLT70) from Escherichia coli is a bacterial exo-muramidase that cleaves the cell wall peptidoglycan, producing 1,6-anhydro-muropeptides. The X-ray structure of SLT70 showed that one of its domains is structurally related to lysozyme, although there is no obvious similarity in amino acid sequence. To relate discrete structural features to differences in reaction mechanism and substrate/product specificity, we compared the three-dimensional structure of the catalytic domain of SLT70 with the structures of three typical representatives of the lysozyme superfamily: chicken-type hen egg-white lysozyme, goose-type swan egg-white lysozyme, and phage-type lysozyme from bacteriophage T4. We find a particularly close relationship between the catalytic domain of SLT70 and goose-type lysozyme, with not only a significant similarity in overall structure, but even a weak homology in amino acid sequence. This finding supports the notion that the goose-type lysozyme takes up a central position in the lysozyme superfamily and that it is structurally closest to the lysozyme ancestors. The saccharide-binding groove is the most conserved part in the four structures, but only two residues are absolutely preserved: the "catalytic" glutamic acid and a structurally required glycine. The "catalytic" aspartate is absent in SLT70, a difference that can be related to a different mechanism of cleavage of the beta-1,4-glycosidic bond. The unique composition of amino acids at the catalytic site, and the observation of a number of differences in the arrangements of secondary structure elements, define the catalytic domain of SLT70 as a novel class of lysozymes. Its fold is expected to be exemplary for other bacterial and bacteriophage muramidases with lytic transglycosylase activity.
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PMID:The catalytic domain of a bacterial lytic transglycosylase defines a novel class of lysozymes. 747 97

The receptor like PTPase, PTP mu, displays structural similarity in its extracellular segment to members of the immunoglobulin superfamily of cell adhesion molecules. The full length form of PTP mu (200 kD) and a construct expressing only the intracellular PTPase domain-containing segment (80 kD) were expressed in the baculovirus/Sf9 cell system, purified and characterized. Full length PTP mu was membrane associated while the truncated form was recovered in the soluble fraction. PTP mu preferentially dephosphorylated a reduced carboxamidomethylated and maleylated derivative of lysozyme (RCML) over other tyrosine phosphorylated substrates such as myelin basic protein (MBP) or the synthetic peptide EDNDYINASL. The enzymatic properties of the soluble, truncated form of the enzyme were examined in detail. The pH optimum was 7.5. It dephosphorylated RCML with a Km of 400 nM and a Vmax of 725 nmol/min/mg. This form of the enzyme was 2 fold more active than full length PTP mu. Trypsinization of the full length form inhibited activity. Vanadate and molybdate, potent tyrosine phosphatase inhibitors, abolished activity of the enzyme. Zn++ and Mn++ ions, polylysine, poly-glu/tyr, and spermine were also inhibitory.
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PMID:Purification and characterization of the human protein tyrosine phosphatase, PTP mu, from a baculovirus expression system. 793 45

The glycosyl-enzyme intermediate in lysozyme action has long been considered to be an oxocarbonium ion, although precedent from other glycosidases and theoretical considerations suggest it should be a covalent enzyme-substrate adduct. The mutation of threonine 26 to glutamic acid in the active site cleft of phage T4 lysozyme (T4L) produced an enzyme that cleaved the cell wall of Escherichia coli but left the product covalently bound to the enzyme. The crystalline complex was nonisomorphous with wild-type T4L, and analysis of its structure showed a covalent linkage between the product and the newly introduced glutamic acid 26. The covalently linked sugar ring was substantially distorted, suggesting that distortion of the substrate toward the transition state is important for catalysis, as originally proposed by Phillips. It is also postulated that the adduct formed by the mutant is an intermediate, consistent with a double displacement mechanism of action in which the glycosidic linkage is cleaved with retention of configuration as originally proposed by Koshland. The peptide part of the cell wall fragment displays extensive hydrogen-bonding interactions with the carboxyl-terminal domain of the enzyme, consistent with previous studies of mutations in T4L.
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PMID:A covalent enzyme-substrate intermediate with saccharide distortion in a mutant T4 lysozyme. 826 98


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