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)

Streptomyces antibioticus ETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cultures, except for reduced heat resistance. Both types of spores were sensitive to lysozyme, which is unusual for Streptomyces spores. Glucose and other carbon sources, which promoted different growth rates, did not affect sporulation efficiency. Nitrogen sources, such as casamino acids, that allowed high growth rates suppressed the sporulation. A remarkable repression was also observed in media with some nitrogen sources that promoted noticeably lower growth rates. In permissive media, with nitrogen sources that permitted relatively high growth rates, sporulation was conditioned to the consumption of ammonium in the medium, but not to that of other nitrogen sources, such as asparagine. Phosphate did not show a repressive effect on sporulation in the assayed conditions.
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PMID:Sporulation of Streptomyces antibioticus ETHZ 7451 in submerged culture. 145 69

The surface of streptococci presents an array of different proteins, each designed to perform a specific function. In an attempt to understand the early events in group A streptococci infection, we have identified and purified a major surface protein from group A type 6 streptococci that has both an enzymatic activity and a binding capacity for a variety of proteins. Mass spectrometric analysis of the purified molecule revealed a monomer of 35.8 kD. Molecular sieve chromatography and sodium dodecyl sulfate (SDS)-gel electrophoresis suggest that the native conformation of the protein is likely to be a tetramer of 156 kD. NH2-terminal amino acid sequence analysis revealed 83% homology in the first 18 residues and about 56% in the first 39 residues with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of eukaryotic or bacterial origin. This streptococcal surface GAPDH (SDH) exhibits a dose-dependent dehydrogenase activity on glyceraldehyde-3-phosphate in the presence of beta-nicotinamide adenine dinucleotide both in its pure form and on the streptococcal surface. Its sensitivity to trypsin on whole organism and its inability to be removed with 2 M NaCl or 2% SDS support its surface location and tight attachment to the streptococcal cell. Affinity-purified antibodies to SDH detected the presence of this protein on the surface of all M serotypes of group A streptococcal tested. Purified SDH was found to bind to fibronectin, lysozyme, as well as the cytoskeletal proteins myosin and actin. The binding activity to myosin was found to be localized to the globular heavy meromyosin domain. SDH did not bind to streptococcal M protein, tropomyosin, or the coiled-coil domain of myosin. The multiple binding capacity of the SDH in conjunction with its GAPDH activity may play a role in the colonization, internalization, and the subsequent proliferation of group A streptococci.
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PMID:A major surface protein on group A streptococci is a glyceraldehyde-3-phosphate-dehydrogenase with multiple binding activity. 150 Aug 54

The sensitivity of bacteriophage T4 lysozyme function to amino acid substitutions at defined positions in and around the longitudinal, hydrophobic strips of 9 alpha-helices was assessed after systematic replacement of each residue in the protein with a series of 13 amino acids. The hydrophobic strips were defined by identifying the longitudinal sectors in the helices with the highest mean residue hydrophobicities. Sensitivity to mutation (the percentage of replacements leading to loss of function) was calculated for each residue in the following positions: whole protein, helices, hydrophobic strips, other positions within the helices, and various positions within the hydrophobic strips as well as their extensions beyond the helices. Substitutions at positions in the hydrophobic strips led more frequently to loss of function than substitutions in the protein as a whole. One subset, the COOH-terminal hydrophobic strip residues, is apparently critical; substitutions of these residues (but not of their NH2-terminal counterparts) led at least as frequently to loss of function as substitutions of solvent-inaccessible residues, and nearly as frequently as substitutions of the most highly conserved residues.
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PMID:Critical functional role of the COOH-terminal ends of longitudinal hydrophobic strips in alpha-helices of T4 lysozyme. 151 18

The optimum conditions for autolysis of Clostridium acetobutylicum ATCC 824 were determined. Autolysis was optimal at pH 6.3 and 55 degrees C in 0.1 M-sodium acetate/phosphate buffer. The ability of cells to autolyse decreased sharply at the end of the exponential phase of growth. Lysis was stimulated by monovalent cations and compounds that complex divalent cations, and inhibited by divalent cations. The autolysin of C. acetobutylicum, which was mainly cytoplasmic, was purified to homogeneity and characterized as a muramidase. The enzyme was identical to the extracellular muramidase in terms of M(r), isoelectric point and NH2-terminal amino acid sequence. The autolysin was inhibited by lipoteichoic acids and cardiolipin but not by phosphatidylethanolamine and phosphatidylglycerol. A mechanism of regulation and fixation involving lipoteichoic acid, cardiolipin and divalent cations is proposed.
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PMID:Autolysis of Clostridium acetobutylicum ATCC 824. 164 27

A metallo-endopeptidase, which appears to be an integral membrane protein of rat kidney, was purified to homogeneity by a series of standard chromatographic procedures. This enzyme significantly hydrolyzed human parathyroid hormone [hPTH(1-84)] and a synthetic substrate Suc-Leu-Leu-Val-Tyr-Mec (Suc = succinyl, Mec = 4-methyl-coumarinyl-7-amide). The purified enzyme had apparent molecular masses of 250 kDa on gel filtration, and 88 kDa and 245 kDa on sodium dodecyl sulfate/polyacrylamide gel electrophoresis under reducing and non-reducing conditions, respectively. Its pH optimum for activity was 8.0-8.5 and its isoelectric point was pH 4.9. Its activity was inhibited by EDTA, EGTA and o-phenanthroline, but not by phosphoramidon. The metal-depleted enzyme was reactivated by the addition of metal ions. The enzyme was also inhibited by chymostatin and eglin C, and by thiol compounds. Of the synthetic substrates examined, the enzyme hydrolyzed only Suc-Leu-Leu-Val-Tyr-Mec, one of the synthetic substrates for alpha-chymotrypsin. It did not hydrolyze synthetic substrates with less than four amino acid residues with tyrosine in the P1 position. The enzyme hydrolyzed hPTH and reduced hen egg lysozyme but did not hydrolyze azocasein or [3H]methyl-casein. NH2-terminal amino acid sequence analyses of the degradation products of hPTH(1-84) and reduced hen egg lysozyme by the purified enzyme revealed that the enzyme preferentially cleaved these peptides at peptide bonds flanked by hydrophilic amino acid residues. Amino acid analyses showed that the main degradation products of PTH were hPTH(17-29), hPTH(30-38) and hPTH(74-84). The ability of the enzyme to hydrolyze peptide bonds flanked by hydrophilic amino acid residues and its inability to degrade azocasein distinguish it from several other kidney endopeptidases reported, such as endopeptidase 24.11 and meprin.
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PMID:A membrane-bound metallo-endopeptidase from rat kidney hydrolyzing parathyroid hormone. Purification and characterization. 188 19

Ammonia-induced cell envelope injury was examined in pure cultures of Escherichia coli and Enterobacter aerogenes. Cell injury, as determined by the ratio of colony-forming units on m-T7 agar to colony-forming units on m-Endo agar, increased with exposure to increasing concentrations of ammonia. Cell envelopes appeared to be the site of injury as indicated by increasing susceptibility to lysozyme with increasing ammonia concentration. Cells exposed to ammonia also exhibited more cellular leakage than control cells. Leakage from cells exposed to ammonia included proteins, and all leaked substances increased in concentration as ammonia concentrations increased. The concentration of 2-keto-3-deoxyoctonate (KDO) in the outer membrane of E. coli increased with ammonia exposure, while KDO concentration in the outer membrane of E. aerogenes decreased. The results suggest that exposure of E. coli cells to high concentrations of ammonia disrupts the outer membrane and lipopolysaccharide-associated proteins, while E. aerogenes cells are affected through the disruption of bonds between KDO and the outer membrane.
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PMID:Ammonia-induced cell envelope injury in Escherichia coli and Enterobacter aerogenes. 224 77

The class II histocompatibilty molecule I-Ak was photoaffinity labeled by NH2- and COOH-terminal photoreactive conjugates of an immunogenic hen egg white lysozyme (HEL) peptide. The labeled alpha and beta chains were digested with protease from Staphylococcus aureus strain V-8 (protease V-8) and/or trypsin, and the proteolytic fragments were separated by high performance liquid chromatography (HPLC) (peptide mapping). Reproducible peptide maps containing a major labeled component were obtained from the three conjugates reported here whose photoreactive group was attached via short spacers of limited flexibility. The COOH-terminal conjugate N-acetyl HEL-(49-61)-iodo-4-azidosalicyloyl thioester (compound 1) labeled hydrophilic tryptic digest fragments on both chains of I-Ak. The labeled digest fragments were homogeneous in reverse-phase and anion-exchange HPLC, indicating that the photoaffinity labeling was site-specific. Conversely, the NH2-terminal conjugate iodo-4-azidosalicyloyl HEL-(46-61) (compound 2: IASA-(46-61)) labeled exceptionally hydrophobic sequences on both chains of I-Ak. The labeling was also site-specific because reverse-phase HPLC of primary digests with protease V-8 and secondary digests with trypsin showed single major labeled components. The labeling of I-Ak by IASA-(46-61) was fully inhibitible by HEL-(46-61). In contrast, IASA attached to the smallest immunogenic peptide 52-61 (compound 3) labeled a distinctly different hydrophilic tryptic fragment. The site of the I-Ak molecule that was photoaffinity labeled by IASA-(46-61) (compound 2) was determined. IASA-(46-61) labeled selectively at Pro-118 of a primary alpha chain fragment most likely encompassing residues 115-134. It labeled Thr-121 of a primary beta chain fragment most likely encompassing residues 109-138. We also obtained evidence that IASA-(46-61) occupied the antigen-specific site; the conjugate stimulated a T-cell hybridoma that recognizes the sequence 52-61 and also competed for the binding of this smaller peptide to I-Ak. Thus, peptides that bind to the allele-specific binding site and are long enough to extend beyond it can interact with a hydrophobic area of class II molecules. This area is formed by sequences of the first halves of the second domain of both alpha and beta chains.
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PMID:The sites in the I-Ak histocompatibility molecule photoaffinity labeled by an immunogenic lysozyme peptide. 235 57

Specific activity was compared between wild-type (WT) neutral protease from Bacillus stearothermophilus and mutant protease (M1; Gly144 replaced by Ala144) with enhanced thermostability. When casein was used as a substrate, M1 showed 1.5-times higher specific activity than that of WT. In contrast, the specific activities of M1 for soluble reduced lysozyme and insulin B chain were lower than those of WT by 17.2 and 13.2%, respectively. After digestion of the insulin A chain by these enzymes, the peptide products were purified and the N-terminal amino acid sequences were determined. WT enzyme cleaved insulin A chain at three sites, whereas no digestion was observed with M1. Using Z-Gly-Leu-NH2 as a substrate, the kinetic parameters were determined. The Km values are nearly equal for both enzymes, whereas the kcat of M1 (240 min-1) was much smaller compared to the WT (830 min-1). The data indicate that the mutation (addition of a methyl group) exerts an effect by changing both the catalytic velocity and thermostability.
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PMID:Addition of a methyl group changes both the catalytic velocity and thermostability of the neutral protease from Bacillus stearothermophilus. 267 40

Measurements of ammonia release provide the first direct evidence that calmodulin becomes extensively deamidated during incubations at 37 degrees C, pH 7.4 or pH 11. A stoichiometry of 0.5 mol of NH3 released/mol of calmodulin is observed after 2 h at pH 11 or after 8-9 days at pH 7.4. These treatments also increase the ability of calmodulin to serve as a substrate for the isoaspartate-specific protein carboxyl methyltransferase from bovine brain. The stoichiometries of methylation are highly correlated with the stoichiometries of ammonia release. Deamidation and increased methyl-accepting capacity also occur in parallel for seven other proteins (aldolase, bovine serum albumin, cytochrome c, lysozyme, ovalbumin, ribonuclease A, and triosephosphate isomerase) upon incubation at pH 11. However, in comparison to calmodulin, these other proteins show very little deamidation and increased methylation capacity following incubation at pH 7.4. Deamidation of calmodulin at pH 7.4 is unaffected by the addition of 10(-7) M Ca2+; however, at 4 X 10(-6) M Ca2+, the rate of deamidation is inhibited by approximately 70%. The Ca2+-protection effect is consistent with the suggestion (B. A. Johnson, N. E. Freitag, and D. W. Aswad, (1985) J. Biol. Chem. 260, 10913-10916) that deamidation occurs preferentially at Asn-60 and/or Asn-97, each of which resides in a distinct Ca2+-binding domain.
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PMID:Deamidation of calmodulin at neutral and alkaline pH: quantitative relationships between ammonia loss and the susceptibility of calmodulin to modification by protein carboxyl methyltransferase. 291 79

A method was developed for extracting enzymes from micro-organisms closely associated with ammonia-treated straw (NH3-S) that had been incubated in nylon bags in the rumen. Incubation of washed straw with 125 ml carbon tetrachloride/l and 20 micrograms lysozyme/ml for 3 h at 37 degrees gave carboxymethylcellulase (EC 3.2.1.4; CMCase) and NAD-linked glutamate dehydrogenase (EC 1.4.1.2; GDH) activities greater than those extracted by sonication. GDH associated with NH3-S increased with incubation time and was highest in sheep receiving a high-barley diet. Particle-bound CMCase activity reached a peak between 16 and 24 h and declined thereafter. Particle-bound GDH activity showed no correlation with dry matter (DM) degradation in the rumens of sheep fed on a range of diets. In contrast, CMCase activity after 24 h was highly correlated with DM degradability of the same samples at 24 h (r 0.98) and 48 h (r 0.94). It was concluded that GDH and CMCase can be used as indices of the total population of colonizing rumen micro-organisms and of the fibre-degrading population respectively, and that these enzymes can therefore be used to assess rapidly and with great sensitivity variations in the rumen environment that affect the rate of fibre breakdown.
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PMID:Use of particle-bound microbial enzyme activity to predict the rate and extent of fibre degradation in the rumen. 303 99


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