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)

From experiments with glycoproteins containing the glycopeptide linkages, arabinose-O-hydroxyproline and galactose-O-serine (plant cell wall glycopeptides), N-acetylgalactosamine-O-serine/threonine (pig submaxillary mucin), and N-acetyl-glucosamine-N-asparagine (fetuin), it is apparent that anhydrous liquid HF, a reagent commonly used by snythetic peptide chemists for the complete removal of protecting groups from synthetic peptides, cleaves the O-glycosidic linkages of neutral sugars in 1 hr at 0 degrees C, and the O-glycosidic linkages of amino sugars in 3 hr at 23 degrees C. The N-glycosidic linkage of N-acetylglucosamine to asparagine is not cleaved under any conditions that have been tested. Sodium dodecyl sulfate gel electrophoresis of bovine serum albumin treated in HF does not show any degradation of peptide bonds. Some relatively stable enzymes (lysozyme and RNase) have been shown by others to retain most of their enzymic activity after short treatment (1 hr at 0 degrees C) in HF. With the specificity of HF at 0 degrees C for neutral sugars it should be possible to generate di- or trisaccharides in high yield from polysaccharides containing both neutral and amino sugars with neutral sugars as the reducing termini.
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PMID:A new approach to the structural determination of glycoproteins and polysaccharides: anhydrous HF solvolysis. 7 2

Surface antigens of Actinomyces viscosus T14V were released from cell walls by digestion with lysozyme. These were separated by ion-exchange and gel filtration chromatography into fractions rich in carbohydrate or protein. The former contained a polysaccharide high in 6-deoxytalose, along with a peptide fragment from the cell wall. In the protein-rich fractions, material of high molecular weight was present, which contained some carbohydrate and up to 14.3% nitrogen. Aspartic acid, threonine, glutamic acid, lysine, alanine, and glycine were detected in these fractions, along with smaller amounts of 10 other amino acids. Most of the alanine was present as the L isomer and thus was not from peptidoglycan. Electron microscopy of the high-molecular-weight material revealed long fibrils, 3.5 to 4.5 nm in diameter, which resembled those seen on bacterial cells. V-specific antiserum, prepared by absorbing anti-A. viscosus T14V serum with cell walls of the avirulent strain (A. viscosus T14AV), did not react with the 6-deoxytalose polysaccharide but reacted well with isolated fibrils, and this was not inhibited by 6-deoxytalose.
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PMID:Surface fibrils (fimbriae) of Actinomyces viscosus T14V. 8 16

Acid carboxypeptidase (EC 3.4.12.-) crystallized from culture filtrate of Penicillium janthinellum has been investigated for its use in carboxy-terminal sequence determination of Z-Gly-Pro-Leu-Gly, Z-Gly-Pro-Leu-Gly-Pro, angiotensin I, native lysozyme, native ribonuclease T1, and reduced S-carboxy-methyl-lysozyme. The examination indicated that proline and glycine were liberated from Z-Gly-Pro-Leu-Gly-Pro. At high enzyme concentration, the enzyme catalyzed complete sequential release of amino acids from the carboxy-terminal leucine to the amino-terminal aspartic acid of angiotensin I. The enzyme released the carboxy-terminal leucine from native lysozyme, however, no release of the threonine from native ribonuclease T1 was observed after a prolonged period of incubation with the enzyme. The sequence of the first nine carboxy-terminal residues of denatured lysozyme, leucine, arginine, S-carboxymethyl-cysteine, glycine, arginine, isoleucine, tryptophane, alanine, and glutamine, could be deduced unequivocally from a time release plot of an incubation mixture with the enzyme.
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PMID:Action of crystalline acid carboxypeptidase from Penicillium janthinellum. 23 51

Procedures for effective cellular lysis and plasmid deoxyribonucleic acid (DNA) isolation from group N streptococci were developed. Cells were grown at 32 degrees C for 4 h in a modified Elliker broth containing 20 mM DL-threonine. After cellular digestion with 2 mg of lysozyme per ml for 7 min at 37 degrees C, 1% sodium dodecyl sulfate exposure resulted in complete and immediate lysis. Lactose (Lac) plasmid species in Streptococcus lactis C2 and S. cremoris B1 (30 and 37 megadaltons, respectively) were demonstrated upon examination of DNA from the cleared lysates by agarose gel electrophoresis. Increasing the lysozyme treatment to 20 min or more resulted in loss of the Lac plasmid, whereas other resident plasmids were unaffected and demonstrable in agarose gels. Diethylpyrocarbonate added before lysis prevented Lac plasmid loss in 20-min lysozyme-treated cells, but was not effective after 40 min of lysozyme treatment. The results suggested that endogenous nuclease activity during the lysozyme treatment period initiated Lac plasmid DNA loss. The development of an efficient lysis procedure for the group N streptococci allowed rapid identification and characterization of plasmid DNA by agarose gel electrophoresis. The plasmid composition of S. lactis C2 and S. cremoris B1, as determined by agarose gel electrophoresis, compared favorably to previous electron microscopic observations.
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PMID:Improved lysis of group N streptococci for isolation and rapid characterization of plasmid deoxyribonucleic acid. 41 55

The bacteriophage T7 0.7 gene encodes a protein which supports viral reproduction under specific suboptimal growth conditions. The 0.7 protein (gp0.7) shuts off host RNA polymerase-catalyzed transcription and also expresses a serine/threonine-specific, cAMP-independent protein kinase (PK) activity. To determine the role of the gp0.7 PK in viral reproduction, the 0.7 gene of the T7(JS78) mutant phage--whose gp0.7 expresses only the PK activity--was cloned in the plasmid expression vector pET-11a. Cells containing the recombinant plasmid were viable, and upon IPTG induction produced a 30-kDa polypeptide, similar in size to the gp0.7-related polypeptide seen in T7(JS78)-infected cells. Extracts of cells containing this polypeptide can phosphorylate the exogenous substrate lysozyme. Expression of plasmid-encoded gp0.7(JS78) in vivo results in phosphorylation of the same proteins which are phosphorylated in T7(JS78)-infected cells; moreover, the plasmid-encoded gp0.7(JS78) is itself phosphorylated. The JS78 mutation changes Gln243 in gp0.7 to an amber codon, which explains the production of the truncated, 30-kDa gp0.7-related polypeptide, and implicates the 11-kDa C-terminal domain in host transcription shut-off. The T7(A23) 0.7 point mutant fails to express PK activity in infected cells. However, the truncated T7(A23)-related polypeptide, expressed from a plasmid, exhibits PK activity in vivo and in vitro, but with an altered specificity. Thus, the A23 mutation, which changes Asp100 to Asn, may identify a substrate recognition determinant.
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PMID:Molecular cloning and expression of the bacteriophage T7 0.7(protein kinase) gene. 131 Jan 78

Extracellular muramidase-2 of Enterococcus hirae ATCC 9790 was purified to homogeneity by substrate binding, guanidine-HCl extraction, and reversed-phase chromatography. A monoclonal antibody, 2F8, which specifically recognizes muramidase-2, was used to screen a genomic library of E. hirae ATCC 9790 DNA in bacteriophage lambda gt11. A positive phage clone containing a 4.5-kb DNA insert was isolated and analyzed. The EcoRI-digested 4.5-kb fragment was cut into 2.3-, 1.0-, and 1.5-kb pieces by using restriction enzymes KpnI, Sau3AI, and PstI, and each fragment was subcloned into plasmid pJDC9 or pUC19. The nucleotide sequence of each subclone was determined. The sequence data indicated an open reading frame encoding a polypeptide of 666 amino acid residues, with a calculated molecular mass of 70,678 Da. The first 24 N-terminal amino acids of purified extracellular muramidase-2 were in very good agreement with the deduced amino acid sequence after a 49-amino-acid putative signal sequence. Analysis of the deduced amino acid sequence showed the presence at the C-terminal region of the protein of six highly homologous repeat units separated by nonhomologous intervening sequences that are highly enriched in serine and threonine. The overall sequence showed a high degree of homology with a recently cloned Streptococcus faecalis autolysin.
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PMID:Cloning and sequence analysis of the muramidase-2 gene from Enterococcus hirae. 134 40

Threonine 59, a helix-capping residue at the amino terminus of the longest helix in T4 phage lysozyme, was substituted with valine, alanine, glycine, serine, asparagine, and aspartic acid. The valine, alanine, and glycine replacements were observed to be somewhat more destabilizing than serine, asparagine, and aspartic acid. The crystal structures of the different variants showed that changes in conformation occurred at the site of substitution, including Asp 61, which is nearby, as well as displacement of a solvent molecule that is hydrogen-bonded to the gamma-oxygen of Thr 59 in wild-type lysozyme. Neither the structures nor the stabilities of the mutant proteins support the hypothesis of Serrano and Fersht (1989) that glycine and alanine are better helix-capping residues than valine because a smaller-sized residue allows better hydration at the end of the helix. In the aspartic acid and asparagine replacements the substituted side chains form hydrogen bonds with the end of the helix, as does threonine and serine at this position. In contrast, however, the Asp and Asn side chains also make unusually close contacts with carbon atoms in Asp 61. This suggests a structural basis for the heretofore puzzling observations that asparagine is more frequently observed as a helix-capping residue than threonine [Richardson, J. S., & Richardson, D. C. (1988) Science 240, 1648-1652] yet Thr----Asn replacements at N-cap positions in barnase were found to be destabilizing [Serrano, L., & Fersht, A. R. (1989) Nature 342, 296-299].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dissection of helix capping in T4 lysozyme by structural and thermodynamic analysis of six amino acid substitutions at Thr 59. 156 17

Ligation of interleukin 2 (IL2) is known to regulate both protein tyrosine and serine/threonine phosphorylation. A family of leukocyte transmembrane proteins whose cytoplasmic domain exhibits intrinsic protein tyrosine phosphatase activity is collectively called CD45 and is identified by a set of common cell surface epitopes. Although CD45 is known to be a phosphoprotein, it is not known how phosphorylation specifically regulates its function. We therefore identified a cell line, the IL4-dependent line CTLL-2.4, in which CD45 could be phosphorylated in response to addition of IL2. These cells are a variant of an IL2-dependent murine cell line which were selected for long-term growth on IL4 but which retain the ability to proliferate on exposure to IL2. Incubation of CTLL-2.4 in low serum concentrations followed by stimulation with IL2 caused a three- to fivefold increase in the phosphorylation of CD45 in a time- and concentration-dependent manner. CD45 in non-stimulated cells contained one major tryptic phosphopeptide, whereas, after exposure of the cells to IL2, two new phosphopeptides were present in CD45. The pattern of IL2-induced phosphorylation was different from that found following addition of phorbol 12-myristate 13-acetate (PMA) to the cells. Although IL2 induced rapid and potent tyrosine phosphorylation in CTLL-2.4 cells, all of the basal and cytokine-activated phosphorylation of CD45 occurred on serine residues. The IL2-stimulated phosphorylation caused no change in the amount of cell surface CD45 and no alteration of its catalytic activity using an artificial tyrosine phosphorylated substrate-RCM-lysozyme. We speculate that the increase in phosphorylation of CD45 may modify its association with potential substrates. The differences in the phosphorylation patterns induced by IL2 and PMA further suggest that more than one kinase can use CD45 as substrate and that IL2 activates a protein serine/threonine kinase different from protein kinase C.
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PMID:Interleukin 2 stimulates serine phosphorylation of CD45 in CTLL-2.4 cells. 185 Mar 60

High-sensitivity differential scanning calorimetry has been applied to the study of the reversible thermal unfolding of the lysozyme of T4 bacteriophage in which the threonine residue at position 157 has been replaced by seven different residues. High-resolution structures derived from X-ray crystallography have been reported for these and six other mutants by Alber et al. [Alber, T., Dao-Pin, S., Wilson, K., Wozniak, J. A., Cook, S. P., & Matthews, B. W. (1987) Nature 330, 41-46]. At pH 2.5 the changes relative to the wild-type protein in the standard free energy of unfolding produced by these mutations indicate apparent destabilizations of 0.6 kcal mol-1 (T157R) to 1.9 kcal mol-1 (T157I), whereas the changes in enthalpy of unfolding range from -5.8 kcal mol-1 (T157N) to 11.9 kcal mol-1 (T157E). Since the denaturations are in all cases accompanied by large changes in heat capacity amounting to 2.5 kcal K-1 mol-1, both the free energies and enthalpies are functions of temperature. An intriguing feature of the present results is the relatively large enthalpy changes and the corresponding compensating entropy changes. Our present understanding of the intramolecular energetics of proteins is insufficient to account for these changes.
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PMID:A differential scanning calorimetric study of the thermal unfolding of seven mutant forms of phage T4 lysozyme. 199 3

The authors studied the effect of some factors, including the conditions of preincubation, the action of 2-mercaptoethanol, EDTA, alpha-amylase, on protoplast production in four strains of Streptococcus lactis caused by lysozyme. The strains differed in the nisin-producing activity and in the structure of the cell walls that were not affected with lysozyme without either preincubation in 2-mercaptoethanol or in a salt medium with minimal inhibitory concentrations of DL-threonine. EDTA and alpha-amylase increased the lysozyme effect. Among seven buffer systems studied the most favourable for protoplast production in S. lactis is the ammonia-citric buffer with EDTA, and the best regeneration medium is the agar salt medium to which, depending on the strain, either glucose or sucrose should be added as a stabilizer.
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PMID:[Various aspects of protoplast production in Streptococcus lactis]. 212 39


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