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)

An alanine racemase (EC 5.1.1.1) mutant (Dal-) of Bacillus subtilis required small amounts of D-alanine to synthesize an osmotically stable cell wall in certain growth media. Investigation of the conditions which caused lysis in hypotonic media revealed that in addition to complex media, such as nutrient broth and acid-hydrolyzed casein, glycine inhibited stable cell wall formation. D-Alanine prevented the glycine inhibition. Up to 99% lysis occurred in both dilute and dense cell suspensions (optical densities up to 110) within 2.5 h after adding 1% glycine to late log phase cultures. Intracellular enzymes recovered from the lysate were as active as those from lysozyme-disrupted cells. No amino acid tested other than glycine induced lysis. Dal- mutants can be used for controlled lysis of bacterial cells to facilitate the isolation of normal intracellular constituents and bioengineered products from fermentation processes. Cell walls of most bacteria contain D-alanine; thus, this strategy should be applicable to a wide variety of microorganisms.
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PMID:Controlled lysis of bacterial cells utilizing mutants with defective synthesis of D-alanine. 313 14

We have developed experimental approaches for the construction of protocellular structures under simulated primitive earth conditions and studied their formation and characteristics. Three types of envelopes; protein envelopes, lipid envelopes, and lipid-protein envelopes are considered as candidates for protocellular structures. Simple protein envelopes and lipid envelopes are presumed to have originated at an early stage of chemical evolution, interaction mutually and then evolved into more complex envelopes composed of both lipids and proteins. Three kinds of protein envelopes were constructed in situ from amino acids under simulated primitive earth conditions such as a fresh water tide pool, a warm sea, and a submarine hydrothermal vent. One protein envelope was formed from a mixture of amino acid amides at 80 degrees C using multiple hydration-dehydration cycles. Marigranules, protein envelope structures, were produced from mixtures of glycine and acidic, basic and aromatic amino acids at 105 degrees C in a modified sea medium enriched with essential transition elements. Thermostable microspheres were also formed from a mixture of glycine, alanine, valine, and aspartic acid at 250 degrees C and above. The microspheres did not form at lower temperatures and consist of silicates and peptide-like polymers containing imide bonds and amino acid residues enriched in valine. Amphiphilic proteins with molecular weights of 2000 were necessary for the formation of the protein envelopes. Stable lipid envelopes were formed from different dialkyl phospholipids and fatty acids. Large, stable, lipid-protein envelopes were formed from egg lecithin and the solubilized marigranules. Polycations such as polylysine and polyhistidine, or basic proteins such as lysozyme and cytochrome c also stabilized lipid-protein envelopes.
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PMID:Construction of protocellular structures under simulated primitive earth conditions. 322 17

We examined folding and secretion of human lysozyme using four mutants each lacking two cysteines expressed in a yeast secretion system. Our results have revealed that the formation of the disulfide bond Cys6/Cys128 in human lysozyme is a prerequisite for correct folding in vivo in yeast. Substitution of Ala for Cys77 and Cys95 gave eight-fold greater secretion of a molecule with almost the same specific activity as that of the native enzyme. Substitutions of the other cysteines gave molecules that were secreted at a lower rate and had lower specific activities than the native enzyme. These are the first findings that the individual disulfide bonds of human lysozyme have different functions in folding and secretion in vivo.
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PMID:Role of disulfide bonds in folding and secretion of human lysozyme in Saccharomyces cerevisiae. 328

The interaction of synthetic peptides corresponding to the signal sequences of Escherichia coli alkaline phosphatase: Lys-Gln-Ser-Thr-Ile-Ala-Leu-Ala-Leu-Leu-Pro-Leu-Leu-Phe-Thr-Pro-Val-Thr- Lys-Ala - OCH3, chicken lysozyme: Met-Lys-Ser-Leu-Leu-Ile-Leu-Val-Leu-Cys(Bzl)-Phe-Leu-Pro-Leu- Ala-Ala-Leu-Gly-OCH2-C6H5 and variant of the chicken lysozyme signal sequence with a charged residue in the hydrophobic region: Lys-Leu-Leu-Ile-Ala-Leu-Val-Leu-Lys-Phe-Leu-Pro-Leu-Ala-Ala- Leu-Gly-OCH3 with model membranes of brain phosphatidylserine (PS) and egg phosphatidylcholine (PC) have been investigated by 90 degrees light scattering and fluorescence spectroscopy. Our results indicate that the association of signal peptides with model membranes results in extensive perturbation of the lipid bilayer so as to cause fusion of PS vesicles and aggregation of PC vesicles. The vesicles are also rendered permeable to hydrophilic molecules like carboxyfluorescein. The variant peptide with the lysine residue in the hydrophobic region also has the ability to perturb lipid bilayers of model membranes.
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PMID:Perturbation of the lipid bilayer of model membranes by synthetic signal peptides. 331 Nov 64

To elucidate the structure-function relationship of the signal sequence for the secretion of human lysozyme by Saccharomyces cerevisiae, we have systematically engineered the hydrophobic segment using the signal sequence of chicken lysozyme. Replacement of Cys 10 with leucine caused a 1.6 times increase in the secretion of human lysozyme. An idealized signal sequence L10 in which 10 consecutive leucines were distributed from the 3rd to the 12th position was 1.8 times as effective as the native sequence. L10 can be generalized as Ln = Met-Arg-(Leu)n-Pro-Leu-Ala-Ala-Leu-Gly, where n = 10. We have also studied the secretory capability of Ln, where n = 6,8,12, and 14, and found that the length, as well as hydrophobicity, of the hydrophobic segment is an important factor in the secretion of human lysozyme by yeast.
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PMID:Engineering of the hydrophobic segment of the signal sequence for efficient secretion of human lysozyme by Saccharomyces cerevisiae. 332 76

Assignments for 1H NMR resonances of 121 of the 129 residues of hen egg white lysozyme have been obtained by sequence-specific methods. Spin systems were identified with phase-sensitive two-dimensional (2-D) correlated spectroscopy and single and double relayed coherence transfer spectroscopy. For key types of amino acid residues, particularly alanine, threonine, valine, and glycine, complete spin systems were identified. For other residues a less complete definition of the spin system was found to be adequate for the purpose of sequential assignment. Sequence-specific assignments were achieved by phase-sensitive 2-D nuclear Overhauser enhancement spectroscopy (NOESY). Exploitation of the wide range of hydrogen exchange rates found in lysozyme was a useful approach to overcoming the problem of spectral overlap. The sequential assignment was built up from 21 peptide segments ranging in length from 2 to 13 residues. The NOESY spectra were also used to provide information about the secondary structure of the protein in solution. Three helical regions and two regions of beta-sheet were identified from the NOESY data; these regions are identical with those found in the X-ray structure of hen lysozyme. Slowly exchanging amides are generally correlated with hydrogen bonding identified in the X-ray structure; a number of exceptions to this general trend were, however, found. The results presented in this paper indicate that highly detailed information can be obtained from 2-D NMR spectra of a protein that is significantly larger than those studied previously.
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PMID:Sequential 1H NMR assignments and secondary structure of hen egg white lysozyme in solution. 334 24

Purified beta-1,4-N-acetylmuramoylhydrolase (muramidase-1; EC 3.2.1.17) of Streptococcus faecium ATCC 9790 has been shown to be covalently substituted with approximately 12 mol equivalents of monomeric 5-mercaptouridine monophosphate. All 12 residues are present on the proteolytically processed 87-kDa active form of the enzyme. A peptide fragment containing 5-mercaptouridine, tyrosine, alanine, glycine, and leucine was isolated consistent with an O-phosphate linkage of the nucleotide to tyrosine.
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PMID:Covalent modification of the beta-1,4-N-acetylmuramoylhydrolase of Streptococcus faecium with 5-mercaptouridine monophosphate. 341 15

On the basis of recent evidence, the natural opiate enkephalins, which previously were believed to be confined to the central nervous system, are now known, in fact, to be released from the adrenal glands by sympathetic activation or trauma. To determine if enkephalins (EKs) affect peripheral function, the influence of synthetic leucine and methionine enkephalin (leuEK and metEK) on several relevant functions of human polymorphonuclear leukocytes was evaluated. Initial attempts to detect interaction of leuEK and metEK with neutrophils yielded inconsistent results. Further studies were done using protease-resistant methionine enkephalin-amide (metEKamide). MetEKamide was able to induce degranulation when present at 10(-3) and 10(-4) mmol/L as determined by release of beta-glucuronidase and lysozyme. Using the under-agarose chemotaxis method, treatment with metEKamide resulted in no change of the neutrophil's chemotactic response to an optimal concentration of the chemotactic peptide formyl-methionyl-leucyl-phenyl-alanine (FMLP). However, responsiveness to low levels of FMLP increased in cells treated with 10(-3)-10(-5) mmol/L metaEKamide. This appeared to be a result of increased chemokinesis of the treated cells. Scanning electron microscopic studies of cells exposed to metEKamide revealed that treatment resulted in changes in neutrophil morphology. When metEKamide itself was tested as a potential chemotactic agent, 10(-2) mmol/L metEKamide in an opposing well served to induce chemotaxis. Our results, along with those of recent studies of EKs as immunomodulators of T cell function, suggest that neurohormones can function as regulators of the immune response.
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PMID:Modulation of human neutrophil function by endogenous opiate enkephalins. 343 73

It is proposed that the stability of a protein can be increased by selected amino acid substitutions that decrease the configurational entropy of unfolding. Two such substitutions, one of the form Xaa----Pro and the other of the form Gly----Xaa, were constructed in bacteriophage T4 lysozyme at sites consistent with the known three-dimensional structure. Both substitutions stabilize the protein toward reversible and irreversible thermal denaturation at physiological pH. The substitutions have no effect on enzymatic activity. High-resolution crystallographic analysis of the proline-containing mutant protein (Ala-82----Pro) shows that its three-dimensional structure is essentially identical with the wild-type enzyme. The overall structure of the other mutant enzyme (Gly-77----Ala) is also very similar to wild-type lysozyme, although there are localized conformational adjustments in the vicinity of the altered amino acid. The combination of a number of such amino acid replacements, each of which is expected to contribute approximately 1 kcal/mol (1 cal = 4.184 J) to the free energy of folding, may provide a general strategy for substantial improvement in the stability of a protein.
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PMID:Enhanced protein thermostability from site-directed mutations that decrease the entropy of unfolding. 347 97

The efficacy, renal effects and nephrotoxicity of a short course of treatment with azthreonam were evaluated in 11 adult patients with urinary tract infection. Azthreonam was administered for 5 days at a daily dose adjusted to the residual renal function of the patients. In the pre-treatment period, during treatment and 10 days after completion of therapy, urine cultures, urinalysis and routine renal function tests (clearance of creatinine, urea and uric acid) were performed and urinary enzymes (alanine-aminopeptidase, gamma-glutamyl-transpeptidase, N-acetyl-beta-D-glucosaminidase, lysozyme) were determined. Renal haemodynamics (glomerular filtration rate and effective renal plasma flow) were measured in the pretreatment period and on the 5th day of therapy. The results confirm the efficacy of azthreonam for treatment of urinary tract infection. Results of renal function tests and measurements of urinary enzymes remained unchanged during and after treatment with azthreonam. These data support the conclusion that azthreonam is an effective antimicrobial agent which does not influence renal function or cause nephrotoxic effects.
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PMID:Azthreonam in the treatment of urinary tract infection: evaluation of efficacy, renal effects and nephrotoxicity. 362 45


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