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

The binding of beta-methyl N-acetylglucosaminide (betaMeGlcNAc) to egg-white lysozyme of hen in the tetragonal crystal form was studied by X-ray diffraction techniques to a resolution of 0.25 nm. The binding of the beta-methyl glycoside is almost identical with the binding of beta-N-acetylglucosamine (betaGlcNAc). Real-space refinement of the lysozyme-alpha/beta GlcNAc and lysozyme-betaMeGlcNAc complexes allowed preliminary analysis of the conformational changes observed on binding monosaccharide inhibitors, specially in the region involving tryptophan-62 and residues 70--76. Tetagonal lysozyme crystals, grown in the absence of acetate ions, were examined by X-ray diffraction to 0.25nm resolution. The resulting difference Fourier synthesis shows no firm evidence for bound acetate ions and indicates only minor conformational changes in the side-chain positions of aspartic acid-101 and asparagine-103. The close similarity of the lysozyme structures in the presence and absence of acetate is contrary to expectations from previous n.m.r. studies.
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PMID:Crystal structures of egg-white lysozyme of hen in acetate-free medium and of lysozyme complexes with N-acetylglucosamine and beta-methyl N-acetylglucosaminide. 69 38

Dicarboxylic amino acids constitute the most numerous residues of insoluble elastin in which are potentially ionizable in the physiological range of pH. These residues are essential in facilitating productive electrostatic interaction between elastase and elastin. The present study has investigated the possibility that the glutamic and aspartic acid residues of elastin are amidated. Acid-labile amide-bound ammonia of elastin was quantitated after hydrolysis of the insoluble protein with 2 M HC1 by incubating aliquots of microdistilled hydrolysates with glutamate dehydrogenase, excess alpha-ketoglutarate, and reduced nicotinamide adenine dinucleotide and measuring the resultant decrease in A340 due to oxidation of the dinucleotide cofactor. It was found that ligament elastin purified by repeated autoclaving contains approximately 2.29 mumol of acid-labile amide nitrogen per 10 mg of protein, a value equivalent to approximately 70% of the total number of dicarboxylic amino acid residues. Independent analysis of the amide content was obtained by amino acid analysis of an esterified and reduced elastin sample in which the free dicarboxylic amino acid residues had been converted to the corresponding alcohol derivatives. This analysis indicated that autoclaved ligament elastin contains approximately 18 glutamine, 3 asparagine, 4 glutamic acid and 5 aspartic acid residues per 1000 residues, in good agreement with the analysis of total acid-labile ammonia. The esterified and reduced elastin derivative was nearly inert as an elastase substrate, consistent with a lack of free dicarboxylic amino acid residues. However, addition of sodium dodecyl sulfate to this elastin derivative restores enzyme-substrate charge complementarity, and the elastin-ligand complex was readily hydrolyzed by elastase at the fully stimulated rate, emphasizing the control such ligands can exert in elastolysis. The amide bonds of elastin were found to be significantly more resistant to hydrolysis by 0.1 M NaOH at 98 degrees C than were those of lysozyme or free amidated amino acids. The finding that most of dicarboxylic amino acid residues of elastin exist at neutral amides further emphasizes the apolar character of elastin and has bearing upon the metabolic susceptibility, ligand-binding ability and structural aspects of this connective tissue protein.
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PMID:Amidated carboxyl groups in elastin. 93 66

Non-glycine residues with positive theta-angles have been identified in four proteins, barley serine proteinase inhibitor CI-2, bacterial ribonuclease (barnase) of Bacillus amyloliquefaciens, hen egg white lysozyme and a basic protein from barley seed (barwin) by use of nuclear magnetic resonance spectroscopy. By accurate measurements of the coupling constant (3)JHNHalpha and integration of the nuclear Overhauser HN-Halpha cross peak, positive theta-angles could be determined reliably to 60 degrees +/- 30 degrees, in full agreement with the crystal structures for lysozyme, barnase and serine proteinase inhibitor CI-2. The work emphasizes that positive theta-angles can also occur in non-glycine residues and in the four proteins, positive theta-angles have been observed for the residue types aspartic acid, asparagine, arginine, serine, glutamine, histidine, tyrosine, tryptophan and phenylalanine. The measured (3)JHNHalpha coupling constants and the intensity of the intraresidue HN-Halpha NOEs agree well with the solution structures of three of the proteins, using the existing parametrization of the Karplus curve (Pardi, A., Billeter, M. and Wuthrich, K. (1984) J. Mol. Biol., 180, 741-751; Ludvigsen, S. Andersen, K.V. and Poulsen, F.M. (1991) J Mol. Biol., 217, 731-736).
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PMID:Positive theta-angles in proteins by nuclear magnetic resonance spectroscopy. 139 67

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

Human lysozyme is a monomeric secretory protein composed of 130 amino acid residues, with four intramolecular disulfide bonds and no oligosaccharides. In this study, a mutant protein, [Ala128] lysozyme, which cannot fold because it lacks a disulfide bond, Cys6-Cys128, was expressed in mouse fibroblasts and was found to be mostly degraded in the cells, whereas the control wild-type lysozyme was quantitatively secreted into the media. The degradation of [Ala128]lysozyme was independent of the transport from the endoplasmic reticulum to the Golgi apparatus. The degradation was greatly inhibited by incubation of cells at 15 degrees C, but was minimally affected by treatment of cells with the lysosomotropic agent, chloroquine, implying a non-lysosomal process. Additional mutations (Gly48-->Ser or Met29-->Thr) were created to make asparagine-linked (N-linked) glycosylation site in the [Ala128]lysozyme, and the resultant double mutants, [Ser48, Ala128]lysozyme and [Thr29, Ala128]lysozyme, were analyzed with respect to their intracellular degradation. These mutant proteins were susceptible to N-linked glycosylation, and were degraded in a similar manner to that of [Ala128] lysozyme, except that the onset of degradation of [Ser48, Ala128]lysozyme and [Thr29, Ala128] lysozyme, but not of [Ala128]lysozyme, was preceded by a lag period of up to 60 min. Furthermore, the degradative double mutants, [Ser48, Ala128]lysozyme and [Thr29, Ala128]lysozyme, were glycosylated post-translationally as well as co-translationally. These observations suggest that there is some interaction between the mechanisms of glycosylation and degradation.
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PMID:Non-lysosomal degradation of misfolded human lysozymes with and without an asparagine-linked glycosylation site. 145 41

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

A new enzyme catalyzing the deamidation of seed storage proteins was found in germinating wheat grains and was partially purified. It also acts on egg lysozyme, horse hemoglobin and reduced RNAse, glutamine and Gly-L-Gln-L-Tyr. No activity was observed when using ovalbumin, serum albumin, RNAse, insulin, asparagine and an asparagine-containing peptide. Only glutaminyl residues appear to be deamidated by this enzyme. It differs from transglutaminase and proved to be a true protein deamidase.
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PMID:Protein deamidase from germinating wheat grains. 163 50

The 15N signal assignment of human lysozyme was carried out by using 1H-1H and 1H-15N two dimensional experiments. To solve the severe overlap problem of the NH signals, uniform labeling of the protein with 15N was introduced. The uniformly 15N labeled protein was prepared using a high-expression system of Saccharomyces cerevisiae. From the analyses of 1H and 15N NMR spectra, all of the backbone 15N signals of the molecule were assigned to each specific residue in the amino acid sequence. Recently published proton signal assignments [Redfield & Dobson (1990) Biochemistry, 29, 7201-7214] were confirmed by these complementary data. In addition, assignments were extended to side chain 15NH2 groups of asparagine and glutamine. Elements of secondary structure were deduced from the pattern of sequential and medium-range NOE connectivities. Two beta-sheets and four alpha-helices could be identified in the protein, which were in good agreement with those determined by X-ray crystallography. The interaction between human lysozyme and its inhibitor N-acetyl-chitotriose was investigated by 15N-1H HMQC spectra. Most of the 15N-NH cross-peaks in the spectra were separated well enough to be followed during the titration experiment. Residues whose NH proton signals decrease in intensity upon complex formation, are located mainly around subsites B, C, and D. Local conformational changes were observed around the fourth helix adjacent to the cleft of human lysozyme.
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PMID:1H and 15N NMR study of human lysozyme. 179 72

A nocardioform bacterium was isolated from the spleen tissue of an armadillo infected with M. leprae and easily propagated in pure culture in mineral salt medium supplemented with only simple C and N sources (e.g., liquid paraffin, tetradecane, ammonium salts, urea, asparagine, gelatin, xanthin, hypoxanthin etc.). Complex organic substances, e.g., tyrosin, casein, peptone, meat extract, egg proteins, serum, blood, yeast extract as well as medium 199, did not support the growth of this organism. Microscopically, the organism consisted of acid-fast, long, slender rods which originated from long, fragmented hyphae, or sporulating mycelial tufts; it was acid-fast (at less than 4.0% H2SO4) which was pyridine-susceptible. It produced DOPA-oxidase and Catalase and was lysozyme resistant; this grew best under reduced O2 tension, at pH 7.0 to 8.0 and 28 degrees C. Serologically, it appeared to be only weakly related to the prototype human multibacillary leprosy-derived (reference) nocardioform strain, Nocardia brasiliensis and N. caviae, but was variably related to several mycobacteria strains.
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PMID:Cultivation of a nocardioform acid-fast chemoautotrophic bacterium from armadillo tissues infected with Mycobacterium leprae. 218 9


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