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)

Surface hydrophobicity has recently been emphasized as an important parameter for functional correlation of proteins. However, evaluations of the parameter by different experimental techniques often do not correlate well with each other. In this paper we have compared surface hydrophobicity of a basic protein with those of beta-lactoglobulin, ovalbumin and lysozyme by fluorescence probe method using ANS as an external probe. Two different fluorimetric approaches to determining the surface hydrophobicity parameter, namely, the slope method and the binding parameter method, follow the same relative order. Denaturants, urea, and guanidine hydrochloride disrupted the hydrophobic clefts of the inhibitor on the surface, causing a drastic reduction of surface hydrophobicity.
...
PMID:Surface hydrophobicity of a low molecular weight basic trypsin subtilisin inhibitor from marine turtle eggwhite. 837 Jun 71

Unfolding profiles of two calcium-binding lysozymes, equine milk lysozyme and pigeon egg-white lysozyme, were obtained by circular dichroism and proton NMR measurements. Equine lysozyme unfolds through a stable molten globule intermediate. The molten globule of equine lysozyme was characterized as more ordered than that of bovine alpha-lactalbumin. On the other hand, pigeon lysozyme unfolds by a two-state mechanism and the intermediate could not be observed in guanidine or thermal unfolding, the same as with conventional non-calcium-binding lysozymes. Thus, from the point of view of the unfolding profile, equine lysozyme belongs to the group of alpha-lactalbumin, but pigeon lysozyme belongs to the conventional lysozyme group.
...
PMID:Comparative study of the stability of the folding intermediates of the calcium-binding lysozymes. 845 85

A hyperstable (hs) variant of chicken egg-white lysozyme with enhanced thermal (delta Tm approximately +10.5 degrees C) and chemical (delta Cm for guanidine hydrochloride denaturation = +1.3 M) stabilities relative to wild-type (WT) was constructed by combining several individual stabilizing substitutions. The free energy difference between the native and denatured states of the hs variant is 3.1 (GdnHCl, 25 degrees C) to 4.0 (differential scanning calorimetry, 74 degrees C) kcal mol-1 greater than that of WT. The specific activity of the hs variant is 2.5-fold greater than that of WT. The choice of mutations came from diverse sources: (1) The I55L/S91T core construct with delta Tm = 3.3 degrees C from WT was available from the accompanying study (Shih P, Holland DR, Kirsch JF, 1995, Protein Sci 4:2050-2062). (2) The A31V mutation was suggested by the better atomic packing in the human lysozyme structure where the Ala 31 equivalent is Leu. (3) The H15L and R114H substitutions were selected on the basis of sequence comparisons with pheasant lysozymes that are more stable than the chicken enzyme. (4) The D101S variant was identified from a screen of mutants previously prepared in this laboratory. The effects of the individual mutations on stability are cumulative and nearly additive.
...
PMID:Design and structural analysis of an engineered thermostable chicken lysozyme. 853 42

We designed mutant lysozymes with N-glycosylation signal sequences (Asn48-Gly49-Thr-50 and Asn87-Ile88-Thr89) by substituting Asp to Asn at positions 48 and 87. When these mutant lysozymes were expressed by using yeast (Saccharomyces cerevisiae) in Burkholder minimum medium, N-glycosylation occurred in both lysozymes. The mutant lysozyme with the oligosaccharide at Asn87 showed a similar character to a reported polymannosyl lysozyme [Nakamura, Takasaki, Kobayashi, and Kato (1993) J. Biol. Chem. 268, 12706-12712; Kato, Takasaki, and Ban (1994) FEBS Lett. 355, 76-80]. As judged from the thermodynamic stabilities of the lysozymes obtained by the guanidine hydrochloride denaturation method, the oligosaccharide-bearing mutant lysozymes were more stable by 0.4-1.6 kcal/mol than the corresponding unglycosylated lysozymes. Therefore, it is suggested that the introduction of an N-glycosylation signal sequence into a protein is an effective means to increase the stability of the protein.
...
PMID:Stabilization of lysozyme by introducing N-glycosylation signal sequence. 890 90

We have characterized the guanidine-induced denaturation of hen egg white lysozyme within the 30-75 degrees C temperature range on the basis of equilibrium fluorescence measurements, unfolding assays, kinetic fluorescence measurements, and differential scanning calorimetry. Analysis of the guanidine denaturation profiles according to the linear extrapolation method yields values for the denaturation Gibbs energy which are about 15 kJ/mol lower than those derived from differential scanning calorimetry. Our results strongly suggest that this discrepancy is not due to deviations from the two-state denaturation mechanism. We propose a new method for the determination of denaturation Gibbs energies from solvent-denaturation data (the constant-delta G extrapolation procedure). It employs several solvent-denaturation profiles (obtained at different temperatures) to generate the protein stability curve at zero denaturant concentration within the -8 to 8 kJ/mol delta G range. The method is model-independent and provides a practical, nonlinear alternative to the commonly employed linear extrapolation procedure. The application of the constant-delta G method to our data suggests that the guanidine-concentration dependence of the denaturation Gibbs energy is approximately linear over an extended concentration range but, also, that strong deviations from linearity may occur at low guanidine concentrations. We tentatively attribute these deviations to the abrupt change of the contribution to protein stability that arises from pairwise charge-charge electrostatic interactions. This contribution may be positive, negative, or close to zero, depending on the pH value and the charge distribution on the native protein surface [Yang, A.-S., & Honig, B. (1993) J. Mol. Biol. 231, 459-474], which may help to explain why disparate effects have been found when studying protein denaturation at low guanidine concentrations. Kinetic m values for lysozyme denaturation depend on temperature, in a manner which appears consistent with Hammond behavior.
...
PMID:A model-independent, nonlinear extrapolation procedure for the characterization of protein folding energetics from solvent-denaturation data. 894 29

The refolding of a partially structured state of hen lysozyme formed in 60% (v/v) 2,2,2-trifluoroethanol (TFE) has been studied using hydrogen exchange pulse labelling monitored by 2D 1H NMR, and by stopped flow fluorescence and CD measurements. The results are compared with similar studies of the refolding of the protein denatured in 6 M guanidine hydrochloride (GuHCl). Two conclusions have emerged from these studies. First, provided that the refolding conditions are identical, the two denatured states fold with very similar kinetics, despite the fact the extensive secondary structure is present in the TFE-denatured state but not in the protein denatured in 6 M GuHCl. This arises because of the rapid equilibration of structure in the species formed in the initial stage of folding. Second, whilst addition of GuHCl to the refolding buffer decreases the rate of folding, low concentrations of TFE increase the rate of folding. The result is consistent with slow steps in the refolding of lysozyme being associated primarily with the reorganisation of hydrophobic interactions rather than of hydrogen bonded structure.
...
PMID:Acceleration of the folding of hen lysozyme by trifluoroethanol. 902 Sep 75

A recent study used calorimetric data and a stoichiometric binding model to derive binding constants, enthalpies, and stoichiometries describing the interaction between proteins and the chemical denaturants, urea and guanidine-HCl (Makhatadze and Privalov, J. Mol. Biol., 226 (1992) 491). In the present study, these parameters have been used to calculate the excess free energy, delta Gex, associated with interactions between chemical denaturants and the three proteins examined in the calorimetric study: ribonuclease A, cytochrome c, and lysozyme. This free energy and its dependence on denaturant concentration, the denaturant m value, have then been compared to experimental results from chemical denaturation experiments. The magnitudes of m values calculated from the calorimetric studies are significantly greater, 20 to 100%, than the observed values in urea. Calculated m values for guanidine-HCl range from about 10% greater than observed values for cytochrome c to over 100% greater for lysozyme. Discrepancies between calculated and observed m values are probably attributable to incomplete binding isotherms in the calorimetric studies. An additional issue raised in this study concerns the correlation of m values with changes in accessible surface areas upon unfolding. For proteins that undergo a two-state unfolding reaction, experimental m values can vary by more than a factor of two for a given protein, depending on the solution conditions. This observation suggests that factors beyond changes in accessible surface areas play a major role in determining m values.
...
PMID:Calorimetrically-derived parameters for protein interactions with urea and guanidine-HCl are not consistent with denaturant m values. 912 38

To improve the sequence ions of a protein in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), proteinase K was used to digest the protein followed by MALDI-MS characterization of the peptide fragments. The primary structures of three proteins, insulin B chain, cytochrome c and lysozyme, were determined by this method. A series of peptide fragments including those differentiated by one residue can be produced from the protein by using proteinase K digestion, thus providing support to the protein sequence. The peptide fragments liberated from proteinase K proteolysis of the insulin B chain allow the protein to be partially sequenced. Furthermore, some of the residues are double or triple checked by generating a variety of fragments. The same method was used to investigate cytochrome c and lysozyme denaturated in 3 M guanidine hydrochloride. The success of the method relies on the intrinsic properties of proteinase K and accurate determination of the peptide fragments by MALDI-MS.
...
PMID:Primary structures of proteins characterized by proteinase K digestion and matrix-assisted laser desorption/ionization mass spectrometry. 940 26

It is shown that simultaneously to the unfolding of hen egg white lysozyme and horse heart cytochrome c the sequential conformational changes and molten globule states can be detected by the combination of proteolysis and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This is demonstrated by the differences among the products and the time courses of native lysozyme as well as those unfolded in 1 and 3 M guanidine hydrochloride (GuHCl) when they were proteolyzed by proteinase K and analyzed by MALDI-MS. Due to the absence of disulfide bonds in the cytochrome c molecule, it is more sensitive to the disturbance of the denaturant. The partially unfolded state as detected at low concentrations of guanidine hydrochloride in our experiment resemble the molten globule state. One of the unique properties of the method described herein is to measure directly the peptide fragment liberated from proteolysis of the protein. It allows the identification of the sensitive sites susceptible to denaturation, which are subsequently cleaved by proteinase K proteolysis.
...
PMID:Protein conformational changes determined by matrix-assisted laser desorption mass spectrometry. 952 57

Early conformational states in the refolding of hen lysozyme from guanidine hydrochloride have been characterized by measuring both the fluorescence and the solvent exchange properties of tryptophan side chains. The indole proton occupancies indicate that at pH 5.5, 25 degrees C, half the protection against pulse labeling occurs in the dead time (4 ms) of the experiment, with the remaining protection developing with a time constant of 55 ms. Comparison of these data with the protection kinetics of backbone amides and with the fluorescence data provides evidence for hydrophobic collapse involving incorporation of tryptophan residues in a solvent-excluded state in advance of stable secondary structure formation. Analysis of the pH dependence of the indole hydrogen exchange protection is consistent with two or more structurally distinct collapsed states, and indicates that the generation of a correctly folded compact hydrophobic core is a key precursor to the formation of persistent native-like structure during refolding.
...
PMID:Characterization of collapsed states in the early stages of the refolding of hen lysozyme. 962 99


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

---