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 enzymic hydrolysis of some proteins (insulin-B-chain-S-sulfonate, S-aminoethylated lysozyme, bovine serum albumin) by immobilized peptidolytic enzymes is reported. Sepharose-bound pronase, trypsin and a protease from Thermoactinomyces sp. (MP), the latter both cross linked by glutaric dialdehyde and an exopeptidase mixture containing Sepharose-bound leucine aminopeptidase, carboxypeptidase A and a crude preparation of prolidase were used. After enzymic hydrolysis nearly all amino acids, except proline, were recovered in a 100% yield compared to the value of an acid reference hydrolysate. Tryptophan and methionine, which are partially destroyed by acid hydrolysis in the presence of oxygen could be recovered completely.
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PMID:[Protein hydrolysis by immobilized enzymes]. 98 21

The presence of the enzymatically active allergens equivalent to Der p I (cysteine protease), Der p III (serine protease) and amylase in extracts of Dermatophagoides pteronyssinus, D. farinae and Euroglyphus maynei was determined using appropriate enzymatic techniques. Biochemical equivalents of all three allergens were present in each extract studied. Studies also showed that the mite extracts contained a variety of other biochemically active enzymes including trypsin, chymotrypsin, carboxypeptidase A and B, glucoamylase and lysozyme. Marked differences in the relative concentrations of some of these enzymes in different mite extracts were observed, particularly trypsin and carboxypeptidase A. The enzymes were physicochemically similar to equivalent enzymes from vertebrate and invertebrate sources. Chromatofocusing studies of faecal extracts derived from D. pteronyssinus and D. farinae showed that several isoforms of each enzyme were present. The data indicated that there were more trypsin isoforms, with pI over a wider range, in extracts prepared from D. pteronyssinus. Proteases and carbohydrases were also found in extracts prepared from faecally enriched material suggesting that they were endoperitrophic and associated with mite digestion. The data suggest that not only are the group I, III and amylase allergens a consistent feature of most pyroglyphid dust mites but also that other proteases and carbohydrases present in mite faeces are allergenic.
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PMID:A comparative study of allergenic and potentially allergenic enzymes from Dermatophagoides pteronyssinus, D. farinae and Euroglyphus maynei. 128 68

Changes in the activities of three gastric and nine pancreatic enzymes plus colipase were determined during postnatal development and weaning in calves. In calves exclusively milk-fed for 2, 7, 28, 56, 70 and 119 d, the enzyme activities per kilogram of empty live weight increased with age for chymotrypsin, elastase, carboxypeptidases A and B, ribonuclease and alpha-amylase, decreased for chymosin, lysozyme and colipase but showed no change in the case of pepsin, trypsin, lipase and phospholipase A2 compared with animals at birth. The greatest increase was that in alpha-amylase activity (about 50-fold between d 2 and 119). In calves weaned between d 28 and 56, all the activities were higher than in milk-fed animals, except that of chymosin (which was slightly lower) and that of colipase (which did not change). At 119 d of age, chymotrypsin, carboxypeptidase A, alpha-amylase and lipase were 1.6- to fourfold higher in ruminants than in preruminants. Thus, most enzyme activities were modified first by colostrum and milk intake, and again upon weaning by development of the forestomachs and ingestion of solid food. These ontogenic patterns might be under the control of many gut regulatory peptides, the plasma concentrations of which changed simultaneously. Some gastric and pancreatic enzymes were correlated to plasma concentrations of these gut regulatory peptides.
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PMID:Gastric and pancreatic enzyme activities and their relationship with some gut regulatory peptides during postnatal development and weaning in calves. 137 46

The knowledge about the differentiation of basophilic leukocytes is fragmentary. This report discusses a detailed phenotypic characterization of molecular markers for hematopoietic differentiation in a basophilic leukemia cell line, KU812. The expression of markers for lymphoid, erythroid, neutrophil, eosinophil, monocytic, megakaryocytic, mast cell and basophil differentiation was analyzed at the mRNA level by Northern blots in the KU812 cells, and for reference, in a panel of human cell lines representative of the different hematopoietic differentiation lineages. KU812 was found to express a number of mast cell and basophil-related proteins, i.e. mast cell tryptase, mast cell carboxypeptidase A, high-affinity immunoglobulin (IgE) receptor alpha and gamma chains and the core protein for heparin and chondroitin sulphate synthesis. We found no expression of a number of monocyte/-macrophage or neutrophil leukocyte markers except for lysozyme. From earlier studies, it has been shown that lysozyme is not expressed in murine mucosal mast cell lines. This finding, together with the expression of the mast cell carboxypeptidase in KU812 might distinguish the phenotype of this cell line from that typical of mucosal mast cell lines in rodents. We found a low level of expression of the eosinophil and basophil marker, major basic protein, which might indicate a relationship between basophils and eosinophils. No expression is, however, detected with the eosinophil-specific markers eosinophil cationic protein, eosinophil-derived neurotoxin or eosinophil peroxidase. We also report an extensive screening for inducers of basophilic differentiation of the KU812 cells. The most efficient protocol of induction included serum starvation which led to a dramatic increase in a number of markers specific for mast cells and basophils such as tryptase, carboxypeptidase A and the heparin core protein. Finally, diisopropylfluorophosphate analysis of total protein extracts from KU812 show four labeled protein bands with sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that this cell line expresses at least three previously undescribed serine proteases of which one or more could be a potential basophil-specific marker(s).
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PMID:Phenotypic characterization of KU812, a cell line identified as an immature human basophilic leukocyte. 163 3

From a consideration of (varphi, Psi) values of the amino acids of myoglobin, lysozyme, the alpha and beta chains of horse oxyhemoglobin, tosyl-alpha-chymotrypsin, and carboxypeptidase A, an empirical procedure of predicting whether amino-acid residues in proteins are in a non-helical or may be in a helical conformation has been developed. The conformation of an amino acid at any position n is considered to be influenced by its nearest neighbors (the amino acids at positions n + 1 and n - 1), and the (varphi, Psi) values of the middle amino acid n for the various tripeptide sequences in the known proteins are tabulated. If helical, the (varphi, Psi) values are plotted to define a helical (varphi, Psi) domain. A 20 x 20 table for all tripeptides (n - 1)-(n)-(n + 1) taken sequentially for the entire chain was constructed; it lists the number of instances in which helical and non-helical conformations for the amino acids at position n were found. Certain sequences are found to be associated exclusively with non-helical and others exclusively with helical conformations, whereas many sequences may be either helical or non-helical. The distribution of non-helical residues serves to limit stretches of permissively helical regions; these are then further examined by the helical wheel method. As applied to cytochrome c from 18 species, the only permissively helical segment found was the stretch 91-101 near the C-terminus. For the variable regions of three light and three heavy chains of immunoglobulins, upper limits of 12 and 17% alpha-helix, respectively, were obtained.
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PMID:An attempt to locate the non-helical and permissively helical sequences of proteins: application to the variable regions of immunoglobulin light and heavy chains. 410 30

The lysozyme of bacteriophage T7 is a bifunctional protein that cuts amide bonds in the bacterial cell wall and binds to and inhibits transcription by T7 RNA polymerase. The structure of a mutant T7 lysozyme has been determined by x-ray crystallography and refined at 2.2-A resolution. The protein folds into an alpha/beta-sheet structure that has a prominent cleft. A zinc atom is located in the cleft, bound directly to three amino acids and, through a water molecule, to a fourth. Zinc is required for amidase activity but not for inhibition of T7 RNA polymerase. Alignment of the zinc ligands of T7 lysozyme with those of carboxypeptidase A and thermolysin suggests structural similarity among the catalytic sites for the amidase and these zinc proteases. Mutational analysis identified presumed catalytic residues for amidase activity within the cleft and a surface that appears to be the site of binding to T7 RNA polymerase. Binding of T7 RNA polymerase inhibits amidase activity.
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PMID:The structure of bacteriophage T7 lysozyme, a zinc amidase and an inhibitor of T7 RNA polymerase. 817 Oct 31

To enhance the already high quality of diffraction data for crystals of the hydrophobic protein crambin, X-ray data were collected at 130 K by the method of H. Hope to 0.83 A resolution. Refinement with PROLSQ yields a model with an R value of 10.5%. The final model had three parameter anisotropic vibration factors for all atoms, which included 367 protein heavy atoms, 372 hydrogen atoms and 144 solvent atoms with one ethanol molecule. Dihedral angles and hydrogen-bonding distances generally agree with earlier studies of high-resolution protein structures, but some new patterns are noted. Solvent-related helix distortions are reminiscent of those described by others. Helix and beta-sheet regions show distinct patterns in their side-chain conformations. Despite crambin's hydrophobic nature, its accessible surface area in the crystal is surprisingly close to that of water-soluble proteins like myoglobin and carboxypeptidase A. More of crambin's hydrophobic surface is buried in the crystal, perhaps accounting for its high order of diffraction. A total of 24% of the 46 residues show discrete disorder at 130 K. This includes five side-chains at both 300 and 130 K, and six more side-chains and an ethanol molecule at 130 K. Disorder is associated with the sequence microheterogeneity at Pro/Ser22 and Leu/Ile25, with space filling or with solvent disorder. Correlated conformations extend over three to five residues. The patterns of disorder in this structure reveal important principles of protein structure and its dynamics. Finding disordered groups correlated over 5 to 8 A suggests that co-ordinated motion extends in groups rather than simply as uncorrelated movement around an atom center. Thermal diffuse scattering experiments on insulin and lysozyme are consistent with this interpretation. Nearly all of the protein-bound solvent has been located. Less than 1% of protein accessible surface area remains uncovered by solvent or crystal contacts. Preliminary analysis of the solvent network reveals two main networks in each of four solvent regions.
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PMID:Atomic resolution (0.83 A) crystal structure of the hydrophobic protein crambin at 130 K. 845 May 43

The sporulation-related gamma-D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 has been analysed by proton-induced X-ray emission. It contains 1 equivalent Zn2+ per mol of protein. As derived from gene cloning and sequencing, the B. sphaericus Zn peptidase I is a two-module protein. A 100-amino-acid-residue N-terminal domain consisting of two tandem segments of similar sequences, is fused to a 296-amino-acid-residue C-terminal catalytic domain. The catalytic domain belongs to the Zn carboxypeptidase A family, the closest match being observed with the Streptomyces griseus carboxypeptidase [Narahashi (1990) J. Biochem. 107, 879-886] and with the family prototype, bovine carboxypeptidase A. The catalytic domain of the B. sphaericus peptidase I possesses, distributed along the amino-acid sequence, peptide segments, a triad His162-Glu165-His307 and a dyad Tyr347-Glu366 that are equivalent to secondary structures, the zinc-binding triad His69-Glu72-His196 and the catalytic dyad Tyr248-Glu270 of bovine carboxypeptidase A respectively. The N-terminal repeats of the B. sphaericus peptidase I have similarity with the C-terminal repeats of the Enterococcus hirae muramidase 2, the Streptococcus (now Enterococcus) faecalis autolysin and the Bacillus phi PZA and phi 29 lysozymes, to which a role in the recognition of a particular moiety of the bacterial cell envelope has been tentatively assigned. Detergents enhance considerably the specific activity of the B. sphaericus peptidase I.
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PMID:Characterization of the sporulation-related gamma-D-glutamyl-(L)meso-diaminopimelic-acid-hydrolysing peptidase I of Bacillus sphaericus NCTC 9602 as a member of the metallo(zinc) carboxypeptidase A family. Modular design of the protein. 850 90

Bacteriophage T7 lysozyme binds to T7 RNA polymerase (RNAP) and regulates its transcription by differentially repressing initiation from different T7 promoters. This selective repression is due in part to a lysozyme-induced increase in the KNTP of the initiation complex (IC) and to intrinsically different NTP concentration requirements for efficient initiation from different T7 promoters. While lysozyme represses initiation, once the enzyme has left the promoter and formed an elongation complex (EC) it is generally resistant to the effects of lysozyme. The mechanism by which the inhibitory effects of lysozyme are largely restricted to the initiation phase of transcription is not well understood. We find that T7 lysozyme destabilizes initial transcription complexes (ITCs) and increases the rate of release of transcripts from these complexes but does not destabilize ECs. However, if the RNA:RNAP interaction proposed to be important for EC stability is disrupted by proteolysis of the RNA-binding domain or use of templates which interfere with establishment of this RNA:RNAP interaction, the EC becomes sensitive to lysozyme. Comparison of the X-ray structures of T7RNAP and of a T7RNAP:T7 lysozyme complex reveals that lysozyme causes the C terminus of the polymerase to flip out of the active site. Experiments in which carboxypeptidase A is used to probe the lysozyme-induced exposure of the C terminus reveal a large decrease in carboxypeptidase sensitivity following transcription initiation, suggesting that interactions with the 3'-end of the RNA help stabilize the active site in a functional (carboxypeptidase protected) conformation. Thus, the resistance of the EC to lysozyme appears to be due to the consecutive establishment of two sets of RNA:RNAP interactions. The first is made with the 3'-end of the RNA and helps stabilize a functional conformation of the active site, thereby suppressing the effects of lysozyme on KNTP. The second is made with a more upstream element of the RNA and keeps the EC from being destabilized by lysozyme binding.
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PMID:Mechanisms by which T7 lysozyme specifically regulates T7 RNA polymerase during different phases of transcription. 1054 43

To design artificial proteases that cleave peptide backbones of a wide range of proteins at selected sites, artificial active sites comprising the Cu(II) complex of cyclen (Cu(II)Cyc) and aldehyde group were synthesized on a cross-linked polystyrene. The aldehyde group was employed as the binding site in view of its ability of reversible formation of imine bonds with epsilon-amino groups of Lys residues exposed on the surface of proteins and Cu(II)Cyc as the catalytic group for peptide hydrolysis. The two polymeric artificial metalloproteases synthesized in the present study cleaved all of the protein substrates examined (myoglobin, gamma-globulin, bovine serum albumin, human serum albumin, lysozyme, and ovalbumin), manifesting saturation kinetic behavior. At 50 degrees C and pH 9.0 or 9.5, K(m) was (1.3-22) x 10(-)(4) M, comparable to those of natural proteases, and k(cat) was (6.0-25) x 10(-)(4) s(-)(1), corresponding to half-lives of 4.6-19 min. Intermediacy of the imine complexes formed between the aldehyde group of the catalyst and the epsilon-amino groups of Lys residues of the substrates was confirmed by the trapping experiment with NaB(OAc)(3)H. MALDI-TOF MS of the proteolytic reaction mixtures revealed formation of various cleavage products. Structures of some of the cleavage products were determined by using carboxypeptidase A and trypsin. Among various cleavage sites thus identified, Gln(91)-Ser(92) and Ala(94)-Thr(95) were the major initial cleavage sites in the degradation of myoglobin by the two catalysts. The selective cleavage of Gln(91)-Ser(92) and Ala(94)-Thr(95) was attributed to general acid assistance in peptide cleavage by Tyr(146) located in proximity to the two peptide bonds. Broad substrate selectivity, high cleavage-site selectivity, and high proteolytic rate are achieved, therefore, by positioning the aldehyde group in proximity to Cu(II)Cyc attached to a cross-linked polystyrene.
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PMID:Artificial metalloprotease with active site comprising aldehyde group and Cu(II)cyclen complex. 1598 87


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