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 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.
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PMID:Structural changes and fluctuations of proteins. II. Analysis of the denaturation of globular proteins. 1 68

A model system of ontogeny was utilized to investigate the development of humoral immunity in both AKR and BALB/c mice. Lethally irradiated adult mice were reconstituted with syngeneic fetal or neonatal liver. These mice were immunized at various times after reconstitution with a series of eight antigens: the bacteriophages F2, phiX-174, and T4; the hapten carrier complexes 2,4 dinitrophenyl-bovine serum albumin and fluorescein-bovine serum albumin; and the small proteins: hen egg lysozyme, sperm whale myoglobin, and bovine pancreatic ribonuclease. Subsequent antibody production to the antigens was assayed with either a direct or a modified bacteriophage neutralization technique. Individual mice responded to the various antigens in a sequential pattern which was basically the same for all mice within each strain. However, there was a marked difference between the two strains in the time at which they developed responsiveness to myoglobin. In order to begin to delineate the separate roles played by B and T cells in the generation of this hierarchical response pattern during ontogeny, the development of anti-DNP and anti-FTC activity was examined in carrier-primed mice. Results of this experiment indicated that functional B cell specificities for the two haptens arise at different times during ontogeny. Further studies are needed to determine whether the hierarchical pattern of immune responsiveness observed for the other antigens is a function of sequential appearance of B cell specificities, T cell specificities, or both.
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PMID:Determinants of the hierarchy of humoral immune responsiveness during ontogeny. 5 70

1, 2-Cyclohexanedione reacts specifically with the guanidino group of arginine or arginine residues at pH 8 to 9 in sodium borate buffer in the temperature range of 25-40 degrees. The single product, N-7, N-8-(1,2-dihydroxycyclohex-1,2-ylene)-L-arginine (DHCH-arginine) is stable in acidic solutions and in borate buffers (pH 8 to 9). DHCH-Arginine is converted to N-7-adipyl-L-arginine by periodate oxidation. The structures of the two compounds were elucidated by chemical and physicochemical means. Arginine or arginyl residues can be regenerated quantitatively from DHCH-arginine by incubation at 37 degrees in hydroxylamine buffer at pH 7.0 FOR 7 TO 8 hours. Analysis of native egg white lysozyme and native as well as oxidized bovine pancreatic RNase, which were treated with cyclohexanedione, showed that only arginine residues were modified. The utility of the method in sequence studies was shown on oxidized bovine pancreatic ribonuclease A. Arginine modification was complete in 2 hours at 35 degrees in borate buffer at pH 9.0 with a 15-fold molar excess of the reagent. The derived peptides showed that tryptic hydrolysis was entirely limited to peptide bonds involving lysine residues, as shown both by two-dimensional peptide patterns and by isolation of the resulting peptides. The stability of DHCH-arginyl residues permits isolation of labeled peptides.
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PMID:Reversible modification of arginine residues. Application to sequence studies by restriction of tryptic hydrolysis to lysine residues. 23 32

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

1. The reactivities of phenylglyoxal (PGO), glyoxal (GO), and/or methylglyoxal (MGO) with several proteins, including ribonuclease A [EC 3.1.4.22] and its derivatives, alpha-chymotrypsin [EC 3.4.21.1], trypsin [EC 3.4.21.4], lysozyme [EC 3.2.1.17], pepsin [EC 3.4.23.1], rennin [EC 3.4.23.4], thermolysin, and insulin and its B chain, have been examined. From analyses of the reaction products, PGO was shown to be the most specific for arginine residues. GO and MGO also reacted rapidly with arginine residues, but they also reacted with lysine residues to a significant extent. A side reaction with N-terminal alpha-amino groups was observed with each of these reagents. 2. Two arginine residues out of four in ribonuclease A, two out of three in alpha-chymotrypsin, one out of two in trypsin, one out of two in pepsin, and one out of five in rennin appeared to react with PGO fairly rapidly, indicating a difference in the relative accessibility of these residues by the reagent. Extensive modification of the arginine residues by PGO occurred with RCM-derivatives of ribonuclease A and insulin B chain. The N-terminal isoleucine residues of alpha-chymotrypsin and trypsin appeared to be unreactive with PGO because of salt bridge formation with an aspartyl residue. The activity of alpha-chymotrypsin toward N-benzoyl-L-tyrosine ethyl ester and the lytic activity of lysozyme were lost rapidly on treatment with PGO, as in the case of ribonuclease A. Pepsin and rennin were only partially inactivated by reaction with PGO.
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PMID:Further studies on the reactions of phenylglyoxal and related reagents with proteins. 32 41

The observed rate constants for base-catalyzed hydrogen exchange reactions between solvent water and peptide nitrogen in lysozyme, ribonculease A, oxidized ribonuclease A, and poly(DL-lysine) are all enhanced by an increase in pressure. Activation volumes have been calculated from the pressure effect on these rate constants. For the folded proteins lysozyme and ribonuclease A, deltaV for base-catalyzed exchange changes from about +9 ml/mol at atmospheric pressure -3 ml/mol at 2500 kg/cm2. The same quantity, determined for the random coil polypeptides oxidized ribonuclease A and poly(DL-lysine), does not show this dependence upon pressure. These effects can be understood either in terms of solvent penetration on the folded proteins or the onset of a small degree of pressure induced unfolding. Possible mechanisms by which such penetration could occur are discussed.
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PMID:Pressure effects on folded proteins in solution. Hydrogen exchange at elevated pressures. 63 47

Circular dichroism spectra have been obtained for albumin, alpha-chymotrypsinogen, collagen, concanavalin A, elastase, hemoglobin, histone f2b, alpha-lactalbumin, lactate dehydrogenase, beta-lactoglobulin, lysozyme, myoglobin, papain, ribonuclease A, and thermolysin in the presence of sodium dodecyl sulfate and dithiothreitol. While all spectra have the shape anticipated for a mixture of random coil and alpha helix, the intensities differ markedly ([theta]222 ranges from --1400 to --15 000 deg cm2/dmol). The variation in the circular dichroism can be quantitatively explained by a model which assumes that the arginyl, histidyl, and lysyl residues have an enhanced probability of propagating a helical segment in the presence of the detergent. The model also permits the computation of dimensional properties (unperturbed end-to-end distance and radius of gyration) for polypeptides of known amino acid sequence. Such computations have been performed for 67 proteins. The computed dimensions are compatible with experimental values and with the molecular weight dependence of the transport properties of the complexes. Furthermore, the model can account for the abnormal transport properties of the sodium dodecyl sulfate complexes formed by ribonuclease A, collagen fragments, and histones f2a1, f2a2, f2b, and f3. Even though some of the protein--sodium dodecyl sulfate complexes have helical contents as high as 50%, their overall conformation more closely approximates that of a random coil than a rod.
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PMID:Conformational properties of the complexes formed by proteins and sodium dodecyl sulfate. 96 36

With the glutathione system that leads to rapid regeneration of reduced lysozyme (Saxena, V. P., and Wetlaufer, D. B. (1971) Biochemistry 9, 5015), reduced pancreatic ribonuclease (RNase) regenerated activity in high yield (greater than 90%) but at a considerably lower rate (t1/2 approximately 75 min). Systematic examination of the effects upon regeneration of the concentrations and ratios of reduced and oxidized glutathione (GSH and GSSG) showed the same broad optima for RNase as were earlier found for lysozyme: [GSSG] = 5 X 10(-4) M, [GSH] = 5 X 10(-3) M. Regeneration of reduced RNase by air oxidation was shown to be inhibitable by 10(-4) M EDTA, whereas the glutathione regeneration was unaffected by EDTA. In addition the air-oxidative regeneration showed a strong temperature dependence, in contrast with the glutathione system. The mechanisms of these two kinds of regenerations are therefore different. Six potentially catalytic metal ions were tested in the air-oxidative regeneration of RNase: Cu2+, Co2+, Mn2+, Fe3+, Zn2+, and Ni2+. Of these, only Cu2+ enhanced the rate of regeneration of RNase activity, although both Cu2+ and Co2+ catalyzed thioloxidation of reduced RNase. The rates and yields of RNase regenerations were independent of protein concentration from 3 X 10(-7) M to 1.2 X 10(-5) M in the glutathione system. Preincubation of freshly dissolved reduced RNase under nonoxidizing conditions before adding glutathione did not change the rate or extent of regeneration. Studies of its pH dependence showed that the glutathione regeneration depends on the deprotonation of prototropic groups with 7.5 less than pK less than 8.0. The major ion exchange chromatographic peaks from glutathione and air-oxidative regenerations appeared to be identical with native RNase, by the criteria of specific activity, chromatographic mobility, and circular dichroic spectra. The glutathione system permits regeneration at much higher RNase concentration than the air regeneration, with rates and yields comparable to the greatest reported for air regeneration.
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PMID:Nonenzymic reactivation of reduced bovine pancreatic ribonuclease by air oxidation and by glutathione oxidoreduction buffers. 119 63

The preferential interactions of bovine serum albumin, lysozyme, chymotrypsinogen, ribonuclease A, and beta-lactoglobulin with polyethylene glycols (PEGs) of molecular weight 200-6,000 have been measured by dialysis equilibrium coupled with high precision densimetry. All the proteins were found to be preferentially hydrated in all the PEGs, and the magnitude of the preferential hydration increased with increasing PEG size for each protein. The change in the chemical potentials of the proteins with the addition of the PEGs had highly positive values, indicating a strong thermodynamic destabilization of the system by the PEGs. A viscosity study of the PEGs showed them to be randomly coiled polymers, as their radii of gyration were related to the molecular weight by Rg = aM0.55. The thickness of the effective shell impenetrable to PEG around protein molecules, calculated from the preferential hydration, was found to vary with PEG molecular weight in similar fashion as the PEG radius of gyration, supporting the proposal (Arakawa, T. & Timasheff, S.N., 1985a, Biochemistry 24, 6756-6762) that the preferential exclusion of PEGs from proteins is due principally to the steric exclusion of PEG from the protein domain, although favorable interactions with protein surface residues, in particular nonpolar ones, may compete with the exclusion. These thermodynamically unfavorable preferential exclusion interactions lead to the action of PEGs as precipitants, although they may destabilize protein structure at higher temperatures.
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PMID:Steric exclusion is the principal source of the preferential hydration of proteins in the presence of polyethylene glycols. 130 92

The interaction of urea and guanidinium chloride with proteins has been studied calorimetrically by titrating protein solutions with denaturants at various fixed temperatures, and by scanning them with temperature at various fixed concentrations of denaturants. It has been shown that the observed heat effects can be described in terms of a simple binding model with independent and similar binding sites. Using the calorimetric data, the number of apparent binding sites for urea and guanidinium chloride have been estimated for three proteins in their unfolded and native states (ribonuclease A, hen egg white lysozyme and cytochrome c). The intrinsic and total thermodynamic characteristics of their binding (the binding constant, the Gibbs energy, enthalpy, entropy and heat capacity effect of binding) have also been determined. It is found that the binding of urea and guanidinium chloride by protein is accompanied by a significant decrease of enthalpy and entropy. At all concentrations of denaturants the enthalpy term slightly dominates the entropy term in the Gibbs energy function. Correlation analysis of the number of binding sites and structural characteristics of these proteins suggests that the binding sites for urea and guanidinium chloride are likely to be formed by several hydrogen bonding groups. This type of binding of the denaturant molecules should lead to a significant restriction of conformational freedom within the polypeptide chain. This raises a doubt as to whether a polypeptide chain in concentrated solutions of denaturants can be considered as a standard of a random coil conformation.
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PMID:Protein interactions with urea and guanidinium chloride. A calorimetric study. 132 62


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