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)

The statistical thermodynamic model of protein structure proposed in paper I is developed with special attention to the hydrophobic interaction. Calorimetric measurements of the thermal denaturation of five globular proteins, ribonuclease A, lysozyme, alpha-chymotrypsin, cytochrome c, and myoglobin, are quantitatively analyzed using the model. The thermodynamic parameters obtained by the least squares method reflect the global, average properties of proteins and are in good agreement with the expected values estimated from experimental and theoretical studies for model peptides. The average bond energy epsilon is well related to the tertiary structure of each protein. However, the difference in the parameters between different proteins is not observed for the cooperative energy ZJ and the chain entropy alpha. The individuality of a protein as far as its structural stability is concerned, is mainly reflected by the parameter gamma specifying the hydrophobic nature of a protein. The model is further applied in the analysis of several aspects of the structural stability of globular proteins. Denaturation induced by denaturants, salts, and pH are also explained by the model in a unified manner.
...
PMID:Structural changes and fluctuations of proteins. II. Analysis of the denaturation of globular proteins. 1 68

Tetrahymena pyriformis strain HSM secretes large quantities of acid hydrolases into the culture medium. An enzyme secreted by the ciliate and capable of degrading walls of streptococci was identified and purified to a considerable degree. The pH optimum of this enzyme was 3--4, and it was eluted after cytochrome c from Sephadex G-75 columns. Unlike lysozyme, the enzyme was thermolabile at pH 2.9, but relatively thermostable at pH 8.1. It degraded 14C-labeled cell walls of streptococci releasing reducing groups. Cell walls prepared from different strains of streptococci differed in susceptibility to this enzyme, the most sensitive strain tested being of group A, type T12. It was shown in immunologic studies that this hydrolase released the group-specific carbohydrate from the walls. Secretions of Tetrahymena from early stationary-phase cultures had more bacteriolytic activity than those from cells from late stationary-phase cultures. Further, cells from cultures grown in glucose-supplemented medium secreted less of the enzyme than ciliates of comparable age grown in unsupplemented proteose-peptone. The newly isolated bacteriolytic enzyme, presumably of lysosomal origin, may be helpful in characterizing streptococcal cell walls.
...
PMID:Partial purification and characterization of a bacteriolytic enzyme secreted by Tetrahymena. 3 68

Highly purified rat beta2-microglobulin (beta2m) as well as cytochrome c and lysozyme were radiolabeled and their catabolism studied in the rat. More than 90 percent of these low molecular weight proteins were removed from the serum within an hour and excreted into the urine by 24 hours. Except for the kidney in which the concentration of these protein is ten- to twentyfold greater than in the serum, there is little evidence that rat tissues are concentrating these proteins. The stomach was found to concentrate radioiodine. The catabolism of rat beta2m differed from that of cytochrome c and lysozyme in that the kidney contained twice as much labeled rat beta2m. In addition, the rat excretes 10 to 15 percent of the injected rat beta2m but only 1 to 5 percent of the cytochrome c or lysozyme. These studies established a basis for turnover studies of beta2m complexed with other cell membrane proteins, for example, HL-A or H-2 peptides.
...
PMID:Catabolism of rat beta2-microglobulin in the rat. 6 90

Degradation of myelin basic protein during incubations with high concentrations of horseradish peroxidase has been demonstrated [Johnson & Cammer (1977) J. Histochem. Cytochem.25, 329-336]. Possible mechanisms for the interaction of the basic protein with peroxidase were investigated in the present study. Because the peroxidase samples previously observed to degrade basic protein were mixtures of isoenzymes, commercial preparations of the separated isoenzymes were tested, and all three degraded basic protein, but to various extents. Three other basic proteins, P(2) protein from peripheral nerve myelin, lysozyme and cytochrome c, were not degraded by horseradish peroxidase under the same conditions. Inhibitor studies suggested a minor peroxidatic component in the reaction. Therefore the peroxidatic reaction with basic protein was studied by using low concentrations of peroxidase along with H(2)O(2). Horseradish peroxidase plus H(2)O(2) caused the destruction of basic protein, a reaction inhibited by cyanide, azide, ferrocyanide, tyrosine, di-iodotyrosine and catalase. Lactoperoxidase plus H(2)O(2) and myoglobin plus H(2)O(2) were also effective in destroying the myelin basic protein. Low concentrations of horseradish peroxidase plus H(2)O(2) were not active against other basic proteins, but did destroy casein and fibrinogen. Although high concentrations of peroxidase alone degraded basic protein to low-molecular-weight products, suggesting the operation of a proteolytic enzyme contaminant in the absence of H(2)O(2), incubations with catalytic concentrations of peroxidase in the presence of H(2)O(2) converted basic protein into products with high molecular weights. Our data suggest a mechanism for the latter, peroxidatic, reaction where polymers would form by linking the tyrosine side chains in basic-protein molecules. These data show that the myelin basic protein is unusually susceptible to peroxidatic reactions.
...
PMID:Proteolytic and peroxidatic reactions of commercial horseradish peroxidase with myelin basic protein. 7 59

The distribution of ribonucleoprotein (RNP) within the mitotic spindle of newt lung epithelial cells was studied with the high voltage electron microscope (HVEM) using Bernhard's uranyl-EDTA-lead staining of thick sections in conjunction with the ribonuclease digestion of fixed cells. The results indicate that aside from ribosomes, the major RNP-containing components of the spindle are the kinetochores and centrioles, both of which stain electron-opaque after EDTA treatment. In both cases, the electron-opaque material associated with these microtubule organizing centers (MTOC's) can be removed by RNAse digestion and cold perchloric acid (PCA) extraction under conditions which leave the spindle microtubules (Mts) centrioles, and kinetochores intact. The staining reaction is not abolished by cold PCA extraction alone or by substituting other positively charged proteins (i.e., cytochrome c or lysozyme) for RNAse. The RNP component of the kinetochore is closely associated with the bases of the kinetochore microtubules. The RNP component of the centriole can be seen to surround the microtubules of the triplet blades. No evidence was found to indicate the presence of RNP in the pericentriolar material. The possible function of both kinetochore and centriolar RNP is discussed.
...
PMID:Ribonucleoprotein staining of centrioles and kinetochores in newt lung cell spindles. 8 14

The aromatic regions in proton-decoupled natural abundance 13C Fourier transform nuclear magnetic resonance spectra (at 14.2 kG) of small native proteins contain broad methine carbon bands and narrow nonprotonated carbon resonances. Some factors that affect the use of natural abundance 13C Fourier transform NMR spectroscopy for monitoring individual nonprotonated aromatic carbon sites of native proteins in solution are discussed. The effect of protein size is evaluated by comparing the 13C NMR spectra of horse heart ferrocytochrome c, hen egg white lysozyme, horse carbon monoxide myoglobin, and human adult carbon monoxide hemoglobin. Numerous single carbon resonances are observed in the aromatic regions of 13C NMR spectra of cytochrome c, lysozyme, and myoglobin. The much larger hemoglobin yields few resolved individual carbon resonances. Theoretical and some experimental values are presented for the natural linewidths (W), spin-lattice relaxation times (T1), and nuclear Overhauser enhancements (NOE) of nonprotonated aromatic carbons and Czeta of arginine residues. In general, the 13C-1H dipolar mechanism dominates the relaxation of these carbons. 13C-14N dipolar relaxation contributes significantly to 1/T1 of C epsilon2 of tryptophan residues and Czeta of arginine residues of proteins in D2O. The NOE of each nonprotonated aromatic carbon is within experimental error of the calculated value of about 1.2. As a result, integrated intensities can be used for making a carbon count. Theoretical results are presented for the effect of internal rotation on W, T1, and the NOE. A comparison with the experimental T1 and NOE values indicates that if there is internal rotation of aromatic amino acid side chains, it is not fast relative to the over-all rotational motion of the protein.
...
PMID:Studies of individual carbon sites of proteins in solution by natural abundance carbon 13 nuclear magnetic resonance spectroscopy. Relaxation behavior. 16 39

The number of 1-anilino-8-naphthalene sulphonate (ANS) molecules bound to black phosphatidylcholine (PC) and phosphatidylinositol (PI)-membranes was calculated. The fluorescences change of membrane bound ANS was measured after the additon of positively charged proteins to the same side as ANS. Cytochrome c caused a fluorescence decrease, lysozyme and protamine an increase. These effects were completely reversible in the case of cytochrome c and lysozyme and only partly reversible in the case of protamine by increasing the ionic strength. The fluorescence polarization of membrane bound ANS was not significantly changed by protein addition. The results are discussed with respect to the binding of proteins to black lipid membranes and the use of ANS as a probe compared with other fluorescent probes.
...
PMID:The use of fluorescent probes for studying the interaction of proteins with black lipid membranes. 16 43

The specifity of Ag+ ions for protein SH groups has been questioned frequently, even though the amperometric titration with AgNO3 is one of the most common methods for the determination of SH groups in proteins. This is due to the fact, that the formation of silver complexes in the titration of cysteine causes a consumption of AgNO3 which is too high. In order to find out if this may be true in the case of proteins, in the present work select proteins with a well known content of SH and SS groups have been titrated amperometrically in tris buffer pH 7.4 with 0.001 M AgNO3. The proteins used were hemoglobin, bovine serum albumin, ovalbumin, lysozyme, pepsin, myoglobin, and cytochrome c. The direct and the indirect titrations of (a) native, (b) denatured, and (c) NaBH4 reduced proteins showed, that the expected consumption of AgNO3 was in no case exceeded. Therefore under the conditions used AgNO3 may be considered as a specific reagent for protein SH groups. High SH values as a result of the amperometric titration of proteins with silver nitrate, which have been published occasionally, may be due to incorrect estimation of the end point of the titration. The reducibility of SS groups depends on the kind of protein. Lysozyme and pepsin were already completely reduced at 23 degrees C, whereas bovine serum albumin needed 60 degrees C. The direct titration method was useful only in some cases for the detection of all SH groups originally present in the proteins or formed by reduction with NaBH4. On the other hand the indirect titration method gave maximum values, because the slowly reacting SH groups of proteins are also allowed to react and the resulting titration curves may be evaluated correctly.
...
PMID:[Determination of sulphydryl and disulphide groups in proteins by amperometric titration. III. Investigation of the specifity of Ag+ ions for protein SH groups (author's transl)]. 17 21

1. Cells of the hydrogen bacterium Alcaligenes eutrophus are broken by gentle lysis using lysozyme treatment in hypertonic sucrose followed by osmotic shock. By this method, 93% of the in vivo activity of the H2 oxidase is recovered and the ATPase remains particle bound. In contrast, cell disruption in a French pressure cell diminishes the in vivo activity of the H2 oxidase by 50% and solubilizes the bulk of the ATPase. 2. The bacterium contains a periplasmic cytochrome c with bands at 418, 521 and 550 nm (difference spectrum). In addition to cytochrome aa3, b-560, c-553 and o, low temperature difference spectra of membranes show the presence of two further cytochromes (shoulders at 551 and 553 nm). 3. The unsupplemented membrane fraction catalyses the oxidation of hydrogen, NADH, NADPH, succinate, formate and endogenous substrate (NAD linked) at rates 2--3-fold higher than membranes obtained from cells disrupted in a French pressure cell. With the exception of the H2 oxidase all oxidase activities in lysozyme membranes are sensitive to carbonylcyanide m-chlorophenylhydrazone (20-100% stimulation of oxygen uptake). 4. The cytoplasmic fraction contains a B-type cytochrome with absorption maxima at 436 and 560 nm, capable of combining with CO; it contains non-covalently bound protohaem. In alkaline solutions a spectral transition to the haemochrome type with bands at 423, 526 and 556 nm occurs. The addition of NADH to an aerobic suspension of this cytochrome elicits new absorption maxima at 418, 545 and 577 nm (difference spectrum), which are believed to represent an oxygenated form of the reduced cytochrome.
...
PMID:Respiratory components and oxidase activities in Alcaligenes eutrophus. 18 46

The phosphate content of rat thymus histones was determined. As expected for a replicating tissue, histones 1 and 2B were more phosphorylated and had higher 32P uptakes than did histones from resting liver nuclei; the other histones all showed 32P uptake, but the phosphate content and uptake of histone 2A was about half that for liver histone 2A. When thymus nuclei were incubated in a slightly hypo-osmotic medium, non-histone proteins and phosphorylated histones were released into solution; this was enhanced if ATP was present in the medium. [gamma-32P]ATP was incorporated into non-histone proteins, including protein P1, and into the ADP-ribosylated form of histone 1; negligible 32P was incprporated into the other, bound, histones. Histones 1 and 2B added to the incubation medium were extensively, and histones 2A and 4 slightly, phosphorylated. Histones released by increasing the ionic strength of the medium were phosphorylated. Added lysozyme and cytochrome c were neither bound nor phosphorylated, but added non-histone protein P1 was phosphorylated, causing other histones to be released from the nuclei, especially histones 2A and 3. The released histones were phosphorylated. gamma-Irradiation decreased 32P uptake into the non-ADP-ribosylated histones 1 and 4; phosphorylation of histone 1 in vitro was unaffected. The importance of non-histone proteins, ATP availability and nuclear protein kinases to the control of histone phosphorylation in vivo is discussed.
...
PMID:Phosphorylation of rat thymus histones, its control and the effects thereon of gamma-irradiation. 19 8


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

---