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

---

Query: EC:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies from this laboratory on the immunochemistry of specific chemical derivatives of native lysozyme and of the two disulfide peptide 62-68 (Cys 64-Cys 80) 74-97 (Cys 76-Cys 94) (i.e. (SS)2-peptide), have established an antigenic reactive site to comprise the spatially contiguous surface residues: Trp 72, Lys 97, Lys 96, Asn 93, Thr 89 and Asp 87. In the present work, the identity of the site was verified by an entirely different and novel approach. The aforementioned amino acids were linked directly into a single linear peptide with an intervening spacer where appropriate and substituting phenylalanine for tryptophan (i.e. Phe-Gly-Lys-Asn-Thr-Asp). This peptide (which does not exist in native lysozyme but simulates a surface region of the protein) possessed a remarkable inhibitory activity towards the reaction of lysozyme with its antisera. The immunochemical reactivity of the peptide was equal to the maximum expected reactivity of the site (i.e. a third of the total antigenic reactivity of lysozyme). These findings define quite conclusively and accurately the reactive site which is clearly composed of spatially adjacent residues that are distant in sequence reacting as if in direct linear linkage. The unequivocal establishment of this concept indicates that antigenic sites need not always be composed of residues in direct peptide linkage in the sequence. The nature of the site may depend on the protein. This unorthodox attack at the problem provides a novel and powerful approach for final delineation of the antigenic reactive sites (and perhaps other types of binding sites) in native proteins, following the completion of accurate narrowing down by chemical methods.
...
PMID:Enzymic and immunochemical properties of lysozyme. XVI. A novel synthetic approach to an antigenic reactive site by direct linkage of the relevant conformationally adjacent residues constituting the site. 5 5

Incorporation of L-[14C]ornithine into gramicidin S by crude, unfractionated lysozyme extracts of Bacillus brevis ATCC 9999 was shown to represent the activity of the gramicidin synthetase complex. Frozen-thawed cells were the source of active extracts, but when cells were shaken in air at 37 degrees C, they rapidly lost activity in a first-order reaction with a half-life of 13 min. Protease inhibitors and inhibitors of energy metabolism had no effect on the inactivation process in frozen-thawed cells. Stabilization was achieved when the cells were shaken in nitrogen or helium instead of air. The addition of dithiothreitol produced a moderate degree of stabilization. The L-ornithine- and D-phenylalanine-activating activities of the gramicidin S synthetase complex were also lost during aeration of the cells. Crude cell-free extracts also lost activity when they were shaken in oxygen, but, in this case, inactivation was slower (half-life of 80 min). Nitrogen also stabilized these cell-free extracts.
...
PMID:Oxygen-dependent inactivation of gramicidin S synthetase in Bacillus brevis. 6 33

Extensively washed, dormant spores of Bacillus subtilis were disrupted with glass beads in buffer at pH 7 in the presence of protease inhibitors. Approximately 31% of the total spore protein was soluble, and another 14% was removed from the insoluble fraction by hydrolysis with lysozyme and washing with 1 M KCl and 0.1% sodium dodecyl sulfate. The residual spore integuments comprised 55% of the total spore proteins and consisted of coats and residual membrane components. Treatment of integuments with sodium dodecyl sulfate and reducing agents at pH 10 solubilized 40% of the total spore protein. Seven low-molecular-weight polypeptide components of this solubilized fraction comprised 27% of the total spore protein. They are not normal membrane components and reassociated to form fibrillar structures resembling spore coat fragments. The residual insoluble material (15% of the total spore protein) was rich in cysteine and was probably also derived from the spore coats. A solubilized coat polypeptide of molecular weight 12,200 has been purified in good yield (4 to 5% of the total spore protein). Five amino acids account for 92% of its total amino acid residues: glycine, 19%; tyrosine, 31%; proline, 23%; arginine, 13%; and phenylalanine, 6%.
...
PMID:Bacillus subtilis spore coats: complexity and purification of a unique polypeptide component. 9 27

Grivet monkeys infected with virulent Francisella tularensis Strain Schu S4 showed significant early changes in serum levels of trace metals, triglycerides and activities of alkaline phosphatase, lactate dehydrogenase and alpha-hydroxybutyrate dehydrogenase. Free amino acid levels decreased slightly and there was a marked increase in the phenylalanine: tyrosine ratio. Serum lysozyme activity and seromucoid levels also increased. Kanamycin therapy produced remission of overt signs but the changes in blood constituents were less readily affected. Immunization with the live vaccine strain of F. tularensis induced transient responses similar to those resulting from Schut S4 infection. Immunized monkeys subsequently challenged with the virulent Schu S4 strain showed no clinical signs or marked changes in blood constituents.
...
PMID:Changes in whole blood and serum components of grivet monkeys with experimental respiratory Francisella tularensis infection. 10 70

This paper demonstrates the existence of regions in eight small globular proteins in which the side chains of sulfur-containing amino acids (cysteine and methionine) alternate in space with side chains of aromatic amino acids (histidine, phenylalanine, tryptophan and tyrosine). The proteins are: rubredoxin, high potential iron protein, cytochrome c, flavodoxin, deoxyhemoglobin, trypsin inhibitor, ribonuclease-S, and lysozyme. The sulfur-pi-bonded 'chains' involve a minimum of five and a maximum of 10 amino acids, and contain the most polarizable atoms within proteins. S-pi-chains give extra stability to the folding of proteins; they may also afford paths for the step-wise movement of electrons.
...
PMID:Chains of alternating sulfur and pi-bonded atoms in eight small proteins. 20 19

Host responses to infectious organisms should be modulated so that tissue-damaging products of inflammatory cells do not produce excessive destruction of normal tissue. Lysozyme, which is continuously secreted by monocytes, which, in turn, migrate relatively late to inflammatory areas, was found to significantly dampen several responses of neutrophils to inflammatory stimulants. Thus, human lysozyme obtained and purified from the urine of patients with monocytic leukemia (but not its structurally similar and comparably cationic analogue, eggwhite lysozyme) depresses chemotaxis of normal neutrophils to activated complement, bacterial supernate, and N-formylmethionyl-phenylalanine. In addition, human (but not eggwhite) lysozyme depresses oxidative metabolism (hexose monophosphate shunt activity) and superoxide generation of neutrophils. The specificity of the suppressive effects was indicated by inhibition studies with rabbit antihuman lysozyme antibody, and with the trisaccharide of N-acetylglucosamine, a specific inhibitor of lysozyme. The results suggest that lysozyme, a product of inflammatory cells themselves, may function in a negative feedback system to modulate the inflammatory response.
...
PMID:Modulation of neutrophil function by lysozyme. Potential negative feedback system of inflammation. 22 43

Human polymorphonuclear neutrophil (PMN) granule extract (25 mug of protein) released 60 percent of the available 35SO4 from labeled rabbit articular cartilage in 0.5 hour at neutral pH. N-acetyl-L-alanyl-L-alanyl-L-prolyl-L-alanine choloromethyl ketone (NAcAAPACK), a specific elastase inhibitor, was only minimally effective against whole granule extract, and N-alpha-tosyl-L-lysine chloromethyl ketone, which inhibits trypsin but not elastase, was completely ineffective. Preparative disc-gel electrophoresis of PMN granule extract revealed two separate regions with independent activity against 35SO4-labeled cartilage. One region contained elastases and when tested alone, was completely inhibited by NAcAAPACK. The other contained lysozyme and two esterases active against N-acetyl-L-phenylalanine-alpha-naphthol. Purified lysozyme proved inactive, suggesting that the chymotrypsin-like esterases were responsible for proteoglycan degradation by this region of the gel.
...
PMID:Identification of neutral proteases in human neutrophil granules that degrade articular cartilage proteoglycan. 23 25

The relationship between neutrophil polymorphonuclear leukocyte (PMN) locomotion and the exocytosis of neutrophil cytoplasmic granules was studied by assessing these processes in cells migrating through micropore filters and by measuring the effects of degranulating stimuli on PMN chemotaxis, orientation, adhesiveness, and ability to bind the chemoattractant f-Met-Leu-[3H]Phe. Studies of cells migrating through cellulose nitrate filters indicated that concentrations of f-Met-Leu-Phe optimal for exocytosis were greater than those optimal for chemotaxis and actually inhibited cell migration. In other studies incubation of PMNs with concentrations of secretagogues causing exocytosis of 30% or greater PMN lysozyme increased cell adhesiveness and inhibited chemotaxis. PMNs that had secreted more than 30% lysozyme appeared round, did not orient in a gradient of chemoattractant, and were capable of significantly less f-Met-Leu-[3H]Phe binding than were control cells. The decreased binding of f-Met-Leu-Phe was not associated with hydrolysis of chemotactic peptide by washed cells, although peptide hydrolysis was caused by cell products secreted extracellularly after vigorous exocytosis. In contrast, when only 10--15% cellular lysozyme was released f-Met-Leu-Phe binding was enhanced significantly and there was no depression of chemotaxis. The data indicate limited exocytosis of intracellular granule contents is associated with increased availability of PMN cehmotactic factor receptors. Vigorous exocytosis is associated with inactivation of chemotactic responsiveness related to increase cell adhesiveness, decreased PMN binding of chemotactic factors, and to hydrolysis of chemoattractants by factors secreted extracellularly.
...
PMID:Role of secretory events in modulating human neutrophil chemotaxis. 37 35

The structural changes of bacteriophage T4 lysozyme during its binding to the inhibitor, i. e. disaccharide-tetrapeptide N-acetylglucosaminyl-N-acetylmuraminyl - L - alanyl-gamma-D-glutaminyl - mesodiaminopimelyl-D-alanine) isolated from Escherichia coli cell wall have been studied. During the inhibitor binding to the protein the degree of helicity decreases by approximately 14% as was shown using the circular dichroism technique. The changes in optical properties of tryptophane, tyrosine and phenylalanine residues detected by UV difference and fluorescence spectroscopy have been observed. Based on the experimental data and a comparison of spatial organization of phage T4 lysozyme and chicken egg-white lysozyme made it possible to develop a structural model of phage T4 lysozyme functioning. This model may account for the differences in specificity of action of bacteriophage T4 and chicken egg-white lysozymes and allows to establish the role of the "extra" part of phage lysozyme. According to the model, at the first stage of binding the peptide part of the substrate comes in contact with the "upper" (with respect to the cleft) part of the protein molecule (residues 106--116 and 135--140). This results in rearrangement of the molecule, with opening of the cleft at the second stage. This makes possible the access of the polysaccharide part of the substrate of the active site and a subsequent hydrolysis of the beta (1 leads to 4) glycoside bond.
...
PMID:[Conformational rearrangements of bacteriophage T4 lysozyme during its binding to the inhibitor]. 38 98

The second derivative absorption spectra of serum albumin, insulin, ribonuclease and lysozyme were measured under various conditions to determine the state and amount of their phenylalanine residues. The second derivative spectra of these proteins were very similar to that of phenylalanine in the region between 245 and 270 nm where tryptophan and tyrosine residues caused no appreciable interference. Denaturation of proteins with urea or guanidine hydrochloride caused decrease in the intensity of the second derivative spectra, but scarcely affected the positions of peaks and troughs. The amounts of phenylalanine residues in proteins calculated from a second derivative spectra of denatured proteins coincided well with those reported in the literature. The states of the phenylalanine residues in the proteins could be deduced from the change in optical intensity on denaturation.
...
PMID:Estimation of state and amount of phenylalanine residues in proteins by second derivative spectrophotometry. 39 35


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

---