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 amino acid sequence of pigeon egg-white lysozyme has been determined. The protein molecule contains a single polypeptide chain of 127 amino acid residues and exhibits only about 60% homology when compared to hen egg-white lysozyme.
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PMID:Amino acid sequence of pigeon egg-white lysozyme. 409 56

A lysozyme-detergent procedure was developed for isolation of tau-particles from cells infected by gene-21 mutants of T4 bacteriophage. These particles have a sedimentation coefficient of 440 +/- 10 S. They contain less than 1% detectable nuclease-resistant DNA, are smaller (650 x 850 A) than normal bacteriophage heads (800 x 1100 A), and exhibit two major bands on 7.5% Na dodecyl sulfate-acrylamide gels. The more prominent band (55,000 daltons) corresponds to the uncleaved, major capsid polypeptide (P23); the other band (32,000 daltons) corresponds to the gene-22 product (P22). Temperature-shift experiments with cells infected with tsN8 (gene 21) mutants were used to study the fate of tau-particles accumulated under nonpermissive conditions. 50 Min after ts N8-infected cells were shifted from the nonpermissive (41.5 degrees ) to the permissive (25 degrees ) temperature, a phage burst occurred that was 75% of that observed with wild-type phage. However, in "pulse-chase" temperature-shift experiments, the radioactive tau-particle peak only slightly decreased (by 10-14%) by 50 min after the shift, whereas an increased amount of radioactivity (about four times as much as the tau-particle decrease) appeared in phage particles. The results suggest that at least two pools of head polypeptides coexist in cells infected with gene-21 mutants. One pool is composed of head subunits assembled into tau-particles, which are mostly aberrant structures; the second pool is composed of head subunits that are incorporated into mature phage when the gene-21 product becomes functional.
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PMID:Bacteriophage T4 head morphogenesis. Isolation, partial characterization, and fate of gene 21-defective tau-particles. 451 24

The three dimensional structure of the lysozyme from bacteriophage T4 has been determined from a 2.5 A resolution electron density map. About 60% of the molecule is in a helical conformation and there is one region consisting of antiparallel beta-structure. The polypeptide backbone folds into two distinct lobes linked in part by a long helix. In the region between the two lobes, there is a cleft which deepens into a hole or cavity, about 6-8 A in diameter, extending from one side of the molecule to the other. This opening is closed off by side chains which extend to within 3-5 A of each other. A number of mutant lysozymes in which residues in the vicinity of the opening are modified have markedly reduced catalytic activity, suggesting that this region of the molecule may be catalytically important. The three dimensional structure of T4 phage lysozyme is quite different from that of hen egg-white lysozyme although it is not clear at this time whether or not the mechanisms of catalysis of the respective enzymes are related.
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PMID:The three dimensional structure of the lysozyme from bacteriophage T4. 453 Feb 93

A procedure for the isolation and purification of competence factor produced in a defined medium by group H streptococci, strain Challis-6, is presented. Partial characterization and chemical analysis of the product are described. The procedure yields competence factor of high purity, as shown by homogeneity in electrofocusing, by electrophoresis in sodium dodecyl sulfate polyacrylamide gels, and by chemical analysis. The data indicate that competence factor is a small, dialyzable, highly basic compound. It is free from lipids, phosphorus, and carbohydrates, and is colorless and thermoresistant. Its biological activity is destroyed by trypsin but not by deoxyribonuclease, ribonuclease, lipase, or lysozyme. Its high isoelectric point of above pH 11.0 suggests that competence factor may be a protamine or a polymer of basic amino acids. The possibility that a polyamine may be an integral part of the polypeptide molecule has not been excluded.
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PMID:Purification and properties of Streptococcal competence factor isolated from chemically defined medium. 501 23

The effect of reduction of intramolecular disulphide bridges on the mobility of proteins in 5% (w/v) polyacrylamide gels in the presence of sodium dodecyl sulphate was investigated. A series of polypeptide polymers, containing up to 68 intramolecular disulphide bridges, was prepared by cross-linking proteins of known structure with glutaraldehyde. These model polypeptides were denatured with heat, sodium dodecyl sulphate and urea, and their mobilities in sodium dodecyl sulphate-polyacrylamide gels compared before and after reduction with dithiothreitol. The mobilities of polypeptides containing no cystine were unaffected by reduction. However, reduction generally decreased the mobilities of polypeptides containing cystine; the extent of this decrease depended on the number of cystine residues originally present in the polypeptide polymer, and on the protein from which the latter was derived. In contrast with their higher oligomers, the monomer of lysozyme and the dimer of ribonuclease increased in mobility after reduction. The reduced polypeptide oligomers formed by reaction with glutaraldehyde were generally found to migrate at a rate significantly faster than was expected from their calculated molecular weights. It was concluded that the use of unreduced proteins and protein aggregates for molecular-weight measurements by the sodium dodecyl sulphate-polyacrylamide-gel method may give erroneous estimates of the molecular weight of any protein being investigated.
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PMID:The effect of cross-links on the mobility of proteins in dodecyl sulphate-polyacrylamide gels. 507 66

A synthetic conjugate, prepared by covalent binding of a lysozyme fragment (sequence 64-83, denoted "loop" peptide) to a synthetic branched polypeptide, elicited in rabbits the formation of antibodies with specificity directed against a unique region in native lysozyme. These anti-"loop" antibodies were isolated immunospecifically on a lysozyme-cellulose immunoadsorbent. Antibodies with a similar specificity were isolated from antilysozyme sera with an immunoadsorbent prepared from the same "loop" peptide. The capacity of the anti-"loop" antibodies to distinguish between the "loop" peptide, containing a disulfide bridge, and the open-chain peptide derived from it suggests that they are directed against a conformation-dependent determinant.
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PMID:Antibodies to a unique region in lysozyme provoked by a synthetic antigen conjugate. 525 53

The average interval between attachment of a 30S ribosomal subunit to bacteriophage T4 lysozyme mRNA and the completion of synthesis of lysozyme protein has been measured in vitro. The measured completion times yield rates of polypeptide chain propagation of 1.6 and 3.0 amino acids per second at 25 degrees C and 31 degrees C, respectively.
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PMID:The chain growth rate of T4 lysozyme in vitro. 526 72

Cloned complementary DNAs encoding chicken ovalbumin, chicken prelysozyme and calf preprochymosin, prochymosin and chymosin were inserted downstream from various viral promoters in modified recombinant "shuttle" vectors. Microinjection of the ovalbumin, prelysozyme and preprochymosin constructs into the nuclei of Xenopus laevis oocytes resulted in the synthesis, segregation in membranes and secretion into the extracellular medium of ovalbumin, lysozyme and prochymosin, respectively. Judging from molecular weight estimations, lysozyme and prochymosin were correctly proteolytically processed while ovalbumin, which lacks a cleavable signal sequence, was glycosylated. Injection of the DNA construct encoding prochymosin without its signal sequence resulted in synthesis of prochymosin protein that was localized exclusively in the oocyte cytoplasm. No immunospecific protein was detected after injection of the DNA encoding mature chymosin. In terms of protein expression in oocytes, the Herpes simplex thymidine kinase (TK) promoter was up to sevenfold more effective than the simian virus 40 (SV40) early promoter, and equally as effective as the Moloney murine sarcoma virus long terminal repeat element. Where tested, protein expression in oocytes was much reduced if DNA sequences encoding the SV40 small t intron and its flanking sequences were present in the constructs. S1 nuclease mapping of transcripts produced after injection of DNAs containing the TK promoter indicated that the majority of transcripts initiated at, or within, two bases of the known "cap" site. However, minor transcripts initiating upstream from this site were observed and one (or more) of these transcripts was responsible for the synthesis of an ovalbumin polypeptide containing a 51 amino acid N-terminal extension. This extended protein remained in the oocyte cytosol. When ovalbumin cDNA was inserted into the vectors with opposite polarity to the viral promoter, expression in oocytes resulted in the predominant synthesis and secretion of a variant ovalbumin with a 21 amino acid N-terminal extension, although some full-length ovalbumin was also synthesized and secreted. S1 mapping revealed the presence, in these oocytes, of transcripts of predicted polarity initiating 118 bases upstream from the wild type ovalbumin initiator ATG, at a previously unreported SV40 "promoter". No protein synthesis was detected after the injection of these reverse-orientation constructs into baby hamster kidney (BHK-21) cells.
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PMID:Efficient expression of cloned complementary DNAs for secretory proteins after injection into Xenopus oocytes. 609 86

An enzyme was identified in human serum which unlike lysozyme cleaved the amide bond between N-acetyl-muramic acid and L-alanine of the peptide side chain of the rigid layer (murein) of Escherichia coli. The N-acetyl-muramyl-L-alanine amidase released all of the peptide side chains including those to which the lipoprotein is bound. A portion of the peptide side chains of the Micrococcus lysodeikticus murein was also hydrolysed from the polysaccharide chains. E. coli, M. lysodeikticus, Bacillus subtilis and Staphylococcus aureus were not killed by the amidase. Treatment of E. coli with EDTA or osmotic shock rendered the cells sensitive to the amidase and they were killed. Possible biological functions of the amidase are discussed. The enzyme was separated from lysozyme in human serum. Gel permeation chromatography indicated a molecular weight of the active enzyme of 82,000 while gel electrophoresis in the presence of sodium dodecyl sulfate revealed a molecular weight of 75,000. Thus, the enzyme probably consists of a single polypeptide chain. Incubation with neuraminidase rendered the amidase more basic suggesting the release of sialic acid residues. The modified glycoprotein disclosed an increased activity to murein. Enzyme activity was inhibited by p-chloromercuribenzene sulfonate and ethyleneglycol-bis(2-aminomethyl) tetraacetate (EGTA) at 1 and 0.2 mM concentration, respectively, whereas EDTA up to 5 mM was without effect. The amidase was also inactivated by agents that reduce disulfide bridges.
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PMID:Murein hydrolase (N-acetyl-muramyl-L-alanine amidase) in human serum. 615 47

Sixteen argyrophil cell carcinomas in 59 gastric scirrhous carcinomas were examined histologically, ultrastructurally, and immunohistochemically for polypeptide hormones, CEA, lysozyme, and HCG. In nine of these 16 tumors, polypeptides such as gastrin, somatostatin, and glucagon were demonstrated. Six of these nine tumors contained all three hormones, and three of these six tumors also had argentaffin cells. In all of these 16 tumors CEA were observed. Eight of them had CEA, lysozyme, and acid mucin synchronously. Of the above six tumors containing three peptides, three produced focal HCG. Ultrastructurally, several types of secretory granules were noted. Histologically, these 16 tumors showed poorly differentiated adenocarcinomas or signet ring cell carcinomas. Macroscopically, generalized type was 11 and localized type five. No hormonal syndrome was detected in any of the patients. It was suggested that these scirrhous argyrophil cell carcinomas of the stomach with the multifunction originate from totipotent immature cells of endodermal origin.
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PMID:Scirrhous argyrophil cell carcinoma of the stomach with multiple production of polypeptide hormones, amine, CEA, lysozyme, and HCG. 617 15


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