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)

The detergents which contain a hydrocarbon side chain longer than 16 cabron atoms were used as a perturbant for the study of protein structure. ta low concentration of cetyldimethylbenzylammonium chloride (CDBA) caused difference spectra for Ac-Trp-OEt and AC-Tyr-OEt. The delta e values at their difference maxima became constant above 30 mM of cetyldimethylbenzylammonium chloride, 1430 at 294 nm for Ac-Trp-OEt and 450 at 288 nm for Ac-Tyr-OEt. These delta e values are higher than any other delta e values resulting from solvent effects by such a remarkably low concentration of organic reagents described in the literature so far. The absence of denaturation blue shift in the difference spectra and the fact that the optical rotatory dispersion of the proteins examined in the present study was not changed significantly by cetyldimethylbenzylammonium chloride indicate that the secondary and tertiary structures of the proteins were not destroyed by cetyldimethylbenzylammonium chloride. These characteristics, together with small overlapping of their difference spectra at 288 and 294 nm were advantageous in the determination of tryptophan and tyrosine residues exposed in glucagon, insulin and alcohol dehydrogenase from yeast. No tyrosine residues in ribonuclease A was accessible to cetyldimethylbenzylammonium chloride. Unusual difference spectrum with a peak at 298 nm was observed for lysozyme which is known to contain tryptophan residues in special environments. Ovalbumin gave a novel unusual difference spectrum with a peak at 290 nm and a shoulder at 298 nm, showing the existence of unusual tryptophan and probably tyrosine residues in the molecule.
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PMID:Interaction between proteins and detergents which contain a hydrocarbon chain longer than 16 carbon atoms. II. Difference spectra of various proteins in cetyldimethyl-benzylammonium chloride. 23 67

The hydrophobic nature of proteins is characterized by a degree of 2-p-toluidinonaphthalene-6-sulphonate (TNS) affinity to them and is pronounced quantitatively in the semi-saturated (C1/2) concentrations. This index correlates directly with the position of TNS emission maximum after the binding with proteins and reversely with the yield of fluorescence. The preparations of phosphofructokinase, lactate dehydrogenase, xantinoxidase, glyceratekinase, lysozyme, RNase during the long (1-2 h) contact with TNS change the values C1/2, that evidences for interaction with the hydrophobic indicator of new structures of protein molecule or for a change in the nature of its linkage itself. An attempt is made to characterize the accessible for TNS hydrophobic nature of individual proteins by a coefficient of molar hydrophobic nature which unites three mentioned characteristics. Serum albumin, insulin, glucogon, alpha chemotrypsin, DNase are most hydrophobic, pyruvate kinase, aldolase, urease, RNase--least hydrophobic, Glycerate kinase, pyruvate decarboxylase, phosphofructokinase, lactate dehydrogenase, alcohol dehydrogenase, xanthinoxidase, trypsin, lysozyme are in intermediate position.
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PMID:[Comparative characteristics of hydrophobic nature of certain proteins by their interaction with 2-p-toluidinonaphthalene-6-sulfonates]. 120 4

Nuclear magnetic quadrupole relaxation appears to be a general method for studying the binding of anions to proteins. This is shown by the increase in transverse quadrupole relaxation rate of 35Cl- and 81Br- in the presence of horse liver alcohol dehydrogenase, lysozyme, trypsin, alpha-chymotrypsin, human carbonic anhydrase, fructose-1,6-bisphosphate aldolase and human serum albumin. Of the many possible binding sites at the surface of a protein (e.g. positively charged amino acid side-chains) only a few account for the main part of the relaxation enhancement. This is shown by the decrease in 35Cl- and 81Br- relaxation rate on addition of functional ligands. Large, kinetically inert, complex anions like Pt(CN)2-4 and Au(CN)-2 are found to act as strong competitors towards halogen ions for the high-affinity anion binding sites of a number of proteins. Titrations with complex anions following the 35Cl- or 81Br- relaxation rates are found to be helpful in attempts to elucidate binding mechanisms. Especially, the complex anions may be useful probes for the discrimination between general and metallic anion binding sites in proteins and they also permit correlation of information from X-ray investigations of crystals with that from physical measurements in solution. From the change in halide ion quadrupole relaxation rate on addition of strongly binding ligands the quadrupole coupling constants of the high affinity Cl- and Br- binding sites are estimated using certain assumptions. It is found that for several proteins, comprising the metal-free proteins but also alcohol dehydrogenase and Escherichia coli alkaline phosphatase, the 35Cl quadrupole coupling constants have approximately the same values. For some other metallo-proteins like carbonic anhydrase and a zinc - serum-albumin complex considerably greater quadrupole coupling constants were obtained. The estimated quadrupole coupling constants are used as a basis for a discussion of the interactions involved in anion-protein interactions.
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PMID:Pt(CN)2-4 and Au(CN)-2: potential general probes for anion-binding sites of proteins. 35Cl and 81Br nuclear-magnetic-resonance studies. 120 23

The relative susceptibilities of lenticular proteins (alpha, beta and gamma-crystallins) and a number of proteins of non-lenticular origin, to hydroxyl radical-mediated peptide bond cleavage were compared. The non-lenticular proteins (bovine serum albumin, ovalbumin, alcohol dehydrogenase, lysozyme, thyroglobulin, beta-amylase, haemoglobin and carbonic anhydrase) were readily cleaved into acid-soluble fragments following 5 hours treatment with copper ions and hydrogen peroxide. In contrast the crystallins were almost totally unaffected by similar treatment. When alpha-crystallin was pre-treated with acid or cleaved into large fragments with cyanogen bromide it became susceptible to hydroxyl radical attack, yet heating the protein did not diminish its resistance. It is suggested that the resistance of alpha-crystallin to the copper/peroxide-mediated fragmentation may be dependent on the conformation of the protein.
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PMID:Differences in susceptibility between crystallins and non-lenticular proteins to copper and H2O2-mediated peptide bond cleavage. 175 88

The thermodynamic constants, associated with the interaction of three proteins with triazine dye affinity sorbents, have been derived from bath and frontal analysis experiments. In cases where mass-transfer restrictions are very high, calculation of the thermodynamic constants directly from frontal analysis experiments could not be achieved. In such cases, a portion of the adsorbate was always present in the effluent, a situation which has its effect as the split peak phenomenon. With Fractogel-based triazine dye affinity sorbents none of the test proteins applied in frontal analysis were adsorbed. A similar behaviour was observed for a Cellufine sorbent during the adsorption of human serum albumin and the Blue Sepharose CL6B sorbent during the adsorption of alcohol dehydrogenase, which displayed much slower apparent adsorption kinetics than observed in the bath experiments. These phenomena were shown to be associated with changes in the gel structure, caused in part by the column packing procedure. Silica-based sorbents performed better in the adsorption of lysozyme in the column mode than soft-gel affinity sorbents, as was evident in the higher capacities and steeper breakthrough curves. At high protein concentrations (feedstock concentration greater than 0.2 mg/ml) breakthrough curves obtained with small- and large-particle-size sorbents, but of constant pore size, were found to be identical. This finding demonstrates that the use of small-particle-size sorbents (e.g. particle diameter, dp less than or equal to 5 microns) for the preparative isolation of proteins may not be justified when operating in the overload mode. With other higher-molecular-weight proteins and the silica-based sorbent systems examined, the small-particle-size sorbents (dp = 5 microns) displayed less symmetrical shapes of their breakthrough curves than the larger-particle-size and soft-gel sorbents. This behaviour was further exacerbated when non-porous glass or silica-based sorbents were utilized. These non-porous affinity sorbents displayed nearly rectangular breakthrough shapes at the onset of the adsorption process, but comparatively slow adsorption kinetics became evident as saturation was approached. This phenomenon has been attributed to surface rearrangement and/or reorientation of the adsorbed proteins, particularly with sorbents of high ligand densities.
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PMID:High-performance liquid chromatography of amino acids, peptides and proteins. XCV. Thermodynamic and kinetic investigations on rigid and soft affinity gels with varying particle and pore sizes: comparison of thermodynamic parameters and the adsorption behaviour of proteins evaluated from bath and frontal analysis experiments. 215 23

Infrared spectra have been obtained for 12 globular proteins in aqueous solution at 20 degrees C. The proteins studied, which vary widely in the relative amounts of different secondary structures present, include myoglobin, hemoglobin, immunoglobulin G, concanavalin A, lysozyme, cytochrome c, alpha-chymotrypsin, trypsin, ribonuclease A, alcohol dehydrogenase, beta 2-microglobulin, and human class I major histocompatibility complex antigen A2. Criteria for evaluating how successfully the spectra due to liquid and gaseous water are subtracted from the observed spectrum in the amide I region were developed. Comparisons of second-derivative amide I spectra with available crystal structure data provide both qualitative and quantitative support for assignments of infrared bands to secondary structures. Band frequency assignments assigned to alpha-helix, beta-sheet, unordered, and turn structures are highly consistent among all proteins and agree closely with predictions from theory. alpha-Helix and unordered structures can each be assigned to only one band whereas multiple bands are associated with beta-sheets and turns. These findings demonstrate a method of analysis of second-derivative amide I spectra whereby the frequencies of bands due to different secondary structures can be obtained. Furthermore, the band intensities obtained provide a useful method for estimating the relative amounts of different structures.
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PMID:Protein secondary structures in water from second-derivative amide I infrared spectra. 215 34

Using 2 or 3 simple Good zwitterionic buffers at a 16 or 18 mmol/L final column concentration of the mixture, natural pH gradients of 4 to 8 and 3 to 9.5, respectively, were generated in a liquid LKB column. The pH gradients, stabilized by an anticonvective sucrose gradient, were linear, reproducible and stable in the electric field up to 5h. The pH gradients were used for isoelectric focusing of a number of impure proteins such as human hemoglobin, bovine serum albumin and chicken egg white lysozyme. The protein components could be well separated in the gradient, were easily recovered and appeared to be quite pure when analyzed by sodium dodecyl sulfate-gel electrophoresis. Furthermore, the pH gradient 4-8 was effectively used to isolate one of the acidic isozyme (pI 5.6) components of mouse liver alcohol dehydrogenase (EC 1.1.1.1) in an enzymatically active state, suggesting that the procedure does not denature proteins. The low cost, the ease with which the pH gradients are formed, their linearity, stability for a sufficient period to allow proteins to reach equilibrium and their subsequent recovery from buffer eluates should make the procedure interesting for electrofocusing of proteins.
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PMID:Column isoelectric focusing in natural pH gradients generated by biological buffers. 233 71

From acrylamide quenching results, analyzed by an itterative non-linear least-squares method, we have shown that the fluorescence of multitryptophan-containing proteins, such as horse-liver alcohol dehydrogenase, 3-phosphoglycerate kinase and lysozyme, can be resolved for different segmental contributions, each characterized by collisional (Ki) and static (Vi) quenching constants. The ability to resolve the heterogeneous fluorescence of proteins makes it possible to follow changes in dynamics of the individual residues. In yeast 3-phosphoglycerate kinase, which contains only two tryptophan residues, three fluorescent fractions, characterized by different accessibility to the quencher, were observed. Two of them are assigned to one of the tryptophan residue. This may be interpreted in terms of conformational fluctuations, which facilitate the access of acrylamide molecules to the buried tryptophan residues.
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PMID:The resolution of heterogeneous fluorescence of multitryptophan-containing proteins studied by a fluorescence-quenching method. 294 4

Heart lipoamide dehydrogenase, liver alcohol dehydrogenase and egg-white lysozyme are photo-oxidized in the presence of various dye sensitizers. The photodynamic process is preceded by the binding between the enzyme and the sensitizers. Among the commonly used dyes, halogenated xanthines and thiazine are effective sensitizers for the photo-inactivation of these three enzymes. Histidine residues are the primary target for the sensitized photo-oxidation that inactivates lipoamide dehydrogenase and alcohol dehydrogenase. However, the destruction of tryptophan residues is responsible for the photo-inactivation of lysozyme. The deuterium medium effect and the quenching effect by various scavengers of the potential photo-oxidative intermediates implicate the participation of the mixed type I-type II mechanism, with the involvement of singlet oxygen being of greater importance, in the photo-inactivation of the enzymes.
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PMID:Dye-sensitized photo-oxidation of enzymes. 315 81

A reference method for the deconvolution of polarized fluorescence decay data is described. Fluorescence lifetime determinations for p-terphenyl, p-bis[2-(5-phenyloxazolyl)]benzene and N-acetyltryptophanamide (AcTrpNH2) show that with this method more reliable fits of the decays can be made than with the scatterer method, which is most frequently used. Analysis of the AcTrpNH2 decay with p-terphenyl as the reference compound yields an excellent fit with lifetimes of 2.985 ns for AcTrpNH2 and 1.099 ns for p-terphenyl (20 degrees C), whereas the AcTrpNH2 decay cannot be satisfactorily fitted when the scatterer method is used. The frequency of the detected photons is varied to determine the conditions where pulse pile-up starts to affect the measured decays. At detection frequencies of 5 kHz and 15 kHz, which corresponds to 1.7% and 5% respectively of the rate of the excitation photons no effects are found. Decays measured at 30 kHz (10%) are distorted, indicating that pile-up effects play a role at this frequency. The fluorescence and fluorescence anisotropy decays of the tryptophan residues in the proteins human serum albumin, horse liver alcohol dehydrogenase and lysozyme have been reanalysed with the reference method. The single tryptophan residue of the albumin is shown to be characterized by a triple-exponential fluorescence decay. The anisotropy decay of albumin was found to be mono-exponential with a rotational correlation time of 26 ns (20 degrees C). The alcohol dehydrogenase has two different tryptophan residues to which single lifetimes are assigned. It is found that the rotational correlation time for the dehydrogenase changes with excitation wavelength (33 ns for lambda ex = 295 nm and 36 ns for lambda ex = 300 nm at 20 degrees C), indicating a nonspherical protein molecule. Lysozyme has six tryptophan residues, which give rise to a triple-exponential fluorescence decay. A single-exponential decay with a rotational correlation time of 3.8 ns is found for the anisotropy. This correlation time is significantly shorter than that arising from the overall rotation and probably originates from intramolecular, segmental motion.
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PMID:Application of a reference convolution method to tryptophan fluorescence in proteins. A refined description of rotational dynamics. 356 97


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