Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
 ...
PMID:Construction of protocellular structures under simulated primitive earth conditions. 322 17

Displacement chromatography was used for the preparative-scale separation of peptides, antibiotics, and proteins. The feed components were both purified and concentrated during the separation processes. The components of a peptide mixture were separated on a reverse-phase analytical column using 2-(2-butoxyethoxy) ethanol as the displacer. The use of organic modifiers in the carrier along with an elevated column temperature of 45 degrees C enabled the efficient separation of relatively hydrophobic peptides by displacement chromatography. In addition, the throughput of the process was significantly increased by carrying out the separation at an elevated flow-rate with no adverse effect on product purity. The antibiotic cephalosporin C was isolated from impurities in a fermentation broth using 2-(2-butoxyethoxy)ethanol as the displacer along with a step change in column temperature. The proteins cytochrome c and lysozyme were purified on a weak cation-exchanger column using cationic polymers as the displacers. While polymers of 60 and 20 kilodaltons were both found to be good displacers for these proteins, only the lower molecular weight polymer was readily removed from the column by standard regeneration techniques.
 ...
PMID:Displacement chromatography of biomolecules. 340 48

With the synthesis of a new, strongly basic Immobiline (pK 10.3 at 10 degrees C) it has been possible to formulate a new pH 10-11 recipe for focusing very alkaline proteins, not amenable to fractionation with conventional isoelectric focusing in carrier ampholyte buffers. In this formulation, water is added as an acidic Immobiline having pK = 14 and a unit molar concentration (or with a pK = 15.74 and standard 55.56 molarity) since around pH 11 its buffering power becomes significant. The gel contains a 'conductivity quencher', i.e. a density gradient incorporated in the matrix, with the dense region located on the cathodic side (pH 11) for (a) smoothing the voltage gradient on the separation cell and (b) reducing the anodic electrosmotic flow due to the net positive charge acquired by the matrix at pH 11 (1 mM excess protonated amino groups to act as counterions to the 1 mm OH- groups in the bulk water solution generated by the local value of pH 11). Excellent focusing is obtained for such alkaline proteins as lysozyme (pI 10.55), So-6 (a leaf protein, pI 10.49), cytochrome c (pI 10.45) and ribonuclease (pI 10.12).
 ...
PMID:Isoelectric focusing in immobilized pH gradients in the pH 10-11 range. 342 69

The glycation (nonenzymatic glycosylation) of several proteins was studied in various buffers in order to assess the effects of buffering ions on the kinetics and specificity of glycation of protein. Incubation of RNase with glucose in phosphate buffer resulted in inactivation of the enzyme because of preferential modification of lysine residues in or near the active site. In contrast, in the cationic buffers, 3-(N-morpholino)propane-sulfonic acid and 3-(N-tris(hydroxymethyl)methyl-amino)-2-hydroxypropanesulfonic acid, the kinetics of glycation of RNase were decreased 2- to 3-fold, there was a decrease in glycation of active site versus peripheral lysines, and the enzyme was resistant to inactivation by glucose. The extent of Schiff base formation on RNAse was comparable in the three buffers, suggesting that phosphate, bound in the active site of RNase, catalyzed the Amadori rearrangement at active site lysines, leading to the enhanced rate of inactivation of the enzyme. Phosphate catalysis of glycation was concentration-dependent and could be mimicked by arsenate. Phosphate also stimulated the rate of glycation of other proteins, such as lysozyme, cytochrome c, albumin, and hemoglobin. As with RNase, phosphate affected the specificity of glycation of hemoglobin, resulting in increased glycation of amino-terminal valine versus intrachain lysine residues. 2,3-Diphosphoglycerate exerted similar effects on the glycation of hemoglobin, suggesting that inorganic and organic phosphates may play an important role in determining the kinetics and specificity of glycation of hemoglobin in the red cell. Overall, these studies establish that buffering ions or ligands can exert significant effects on the kinetics and specificity of glycation of proteins.
 ...
PMID:Effect of phosphate on the kinetics and specificity of glycation of protein. 358 12

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.
 ...
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

Deoxyribonucleic acid (DNA)-mediated transformation of Bacillus subtilis can be inhibited by antibodies which specifically interact with single-stranded DNA. This inhibition occurs at a time when the transformation reaction is insensitive to deoxyribonuclease. Studies with radioactive proteins revealed that the maximal binding of gamma globulin occurs immediately preceding the development of maximal competence in the population. Other proteins, such as deoxyribonuclease cytochrome c and serum albumin also adsorb to the surface of the cell. After treatment with lysozyme, 67% of the radioactive gamma globulin remains associated with the cytoplasmic membrane. These findings suggest that the DNA is complexed in a deoxyribonuclease-insensitive form to the surface of the cell and is converted to a single-stranded state prior to transport past the membrane and integration into the chromosome.
 ...
PMID:Binding of rabbit gamma globulin by competent Bacillus subtilis cultures. 418 94

Yeast cells, Candida utilis, in water suspension and in the absence of electrolytes were found to be very sensitive to several proteins of moderate size, including ribonuclease, protamine, lysozyme, bovine serum albumin, cytochrome c, and myoglobin. Viability ceases rapidly, and ultraviolet-absorbing compounds (260 mmu) and the amino acid pool are released into the medium. The ultraviolet-absorbing material appears to be the nucleotide and coenzyme fraction usually extracted by 0.2 n perchloric acid at low temperature. The ribonucleic acid fraction remains in the cell ghosts and can be released by ribonuclease. The enzymatic properties of some of these proteins have no relation to their damaging effect on the cell membrane. Poly-l-lysine shows the same activity.
 ...
PMID:Effect of some proteins on the yeast cell membrane. 429 20

A second extracellular protease from myxobacter strain AL-1 has been purified to homogeneity and named protease II; the enzyme crystallizes as fine needles. The extracellular, cell wall lytic protease reported previously from the same organism is now designated protease I. Protease II exhibits a pH optimum of 8.5 to 9.0 and is stable from pH 3.0 to 9.0. The enzyme is heat stable at 50 C for 18 hr. Results of sedimentation equilibrium studies yielded a molecular weight of 17,000, and amino acid analysis revealed 157 residues with a minimal molecular weight of 16,660. Cleavage of peptide bonds in the oxidized B-chain of insulin, cytochrome c (horse heart). lysozyme, and vasopressin is restricted to the amino side of lysine. Dilysine and trilysine were not hydrolyzed. Products from digestions of polylysine were lysine and dilysine.
 ...
PMID:Myxobacter AL-1 protease II: specific peptide bond cleavage on the amino side of lysine. 434 25

A method for studying inhibitors of the contact stages of blood coagulation is described. A number of positively charged substances were shown to inhibit the contact stages. The inhibitory substances include spermine, cytochrome c, ribonuclease, and lysozyme. The inhibitory effect of these substances was neutralized by the addition of an activated plasma thromboplastin antecedent, factor XI, (PTA) fraction. Other positively charged substances including protamine, hexadimethrine, polylysine, polyornithine, methylene blue, and ortho-toluidine blue also inhibited the contact stages of coagulation, but the inhibitory effect on coagulation was not neutralized by the activated PTA fraction. Negatively charged substances such as heparin and insulin did not inhibit the contact stages of coagulation. Cytochrome c inhibited Celite adsorption of a partially purified Hageman factor fraction, and cytochrome, ribonuclease, spermine, and lysozome inhibited the adsorption of Hageman factor from PTA-deficient plasma. Very much smaller quantities of Celite completely adsorbed Hageman factor from the fraction rather than from whole plasma, which suggested the possibility that plasma contains an inhibitor or inhibitors of Hageman factor adsorption. Furthermore cytochrome c, spermine, ribonuclease, and lysozyme inhibited the coagulant activity of the following activators of the Hageman and PTA factors: Celite, kaolin, sodium stearate, ellagic acid, and skin. It is suggested that negatively charged sites on these activators are critical for adsorption and activation and that inhibition results from neutralization of the negatively charged sites by the adsorbed inhibtor. Tests with polylysine polymers indicate that inhibitory activity is directly related to molecular size over the molecular weight range of 4000 to 100,000.
 ...
PMID:Inhibition of Hageman factor activation. 564 60

1. The reaction of several peptides and proteins with diborane was studied under different conditions to determine those most suitable for the specific reduction of carboxyl groups. 2. In the reaction of model peptides and the cyclic peptides bacitracin and tyrocidin, reduction at 0 degrees was entirely specific for the carboxyl groups without affecting the peptide bonds. Acid amide residues were not reduced. Some tripeptides showed anomalous results in that the C-terminal residue was quite resistant to reduction. 3. Specific reduction of carboxyl groups was achieved in each of the following proteins: human serum albumin, egg albumin, adult human haemoglobin, sperm-whale apomyoglobin, horse heart cytochrome c and egg-white lysozyme. The C-terminal amino acid was usually reduced. 4. Conditions for specific reduction of all available carboxyl groups are not easily found and may vary from one substance to another. Specific reduction of a limited number of available carboxyl groups may be generally accomplished by reactions at -10 degrees . 5. It is suggested that this chemical modification, which has the advantage of permanence, may be useful in studying the role of carboxyl groups in the conformation of proteins and in the biological properties of peptides and proteins.
 ...
PMID:Specific reduction of carboxyl groups in peptides and proteins by diborane. 577 82


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>