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)

Treatment of the cell wall tetrasaccharide GlcNAcbeta(1 leads to 4)-MurNAc-beta(1 leads to 4)-GlcNAc-beta(1 leads to 4)-MurNAc with alkali resulted in the formation of the unsaturated tetrasaccharide GlcNAc-beta(1 leads to 4)-MurNAc-beta(1 leads to 4)-GlcNAc-beta(1 leads to 4)-delta2,3-2-acetamido-2-deoxy-D-glucoseen. The same compound was also formed by transglycosylation upon incubation of the unmodified tetrasaccharide with the unsaturated disaccharide GlcNAc-beta(1 leads to 4)-delta2,3-2-acetamido-2-deoxy-D-glucoseen (Tipper, D. J. (1968) Biochemistry 7, 1441-1449) and hen egg white lysozyme. The unsaturated tetrasaccharide was further characterized by paper electrophoresis, amino sugar analysis, and NMR. From NMR analysis it is concluded that the delta2,3-2-acetamido-2-deoxy-D-glucoseen at the reducing end of the unsaturated tetrasaccharide has a half-chair conformation. This conformation is similar to the one proposed for the sugar at subsite D in the lysozyme-substrate complex in the transition state. Addition of the unsaturated tetrasaccharide to a solution of hen egg white lysozyme quenched the fluorescence of the enzyme and shifted the fluorescence maximum to the blue, similar to the effect produced by the parent compound. The association constant of the unsaturated tetrasaccharide and lysozyme was measured at pH 6.0 and 24 degrees by spectrofluorimetry and microcalorimetry and found to be 1.45 X 10(5) M-1 and 2.5 X 10(5) M-1, respectively. The average value is 100 times higher than that found for the binding of unmodified tetrasaccharide to the enzyme under the same conditions. The unsaturated tetrasaccharide proved to be a better inhibitor of the lysis of Micrococcus luteus cells than the parent compound by a factor of 35. These results support the hypothesis that the active site of the enzyme is constructed so as to bind the transition state for the reaction it catalyzes more firmly than the substrate itself.
...
PMID:A transition state analog of lysozyme catalysis prepared from the bacterial cell wall tetrasaccharide. 0 76

The resonances of nonprotonated aromatic carbons in natural abundance 13C NMR spectra of hen egg white lysozyme are assigned to specific residues of the amino acid sequence. Chemical shift considerations, the effect of pH, and partially relaxed Fourier transform NMR spectra are used to assign each resonance to one of the seven types of nonprotonated aromatic carbons of amino acid residues. Spectra of chemically modified lysozyme samples yield various assignments to specific residues in the sequence. Line-broadening effects caused by binding of the relaxation probes Gd3+ and 4-N-acetamido-2,2,6,6-tetramethylipiperidine-1-oxyl yield specific assignments which are fully consistent with those based on chemical modifications. The effects of paramagnetic shift reagents and amino sugar inhibitors do not yield any obvious specific assignments. The effect of pH on the chemical shift of Cgamma of His-15 yields a pKalpha in agreement with published values, and indicates that the imidazole form of His-15 exists mainly (or entirely) as the Nepsilon3-H tautomer. The effect of pH on the chemical shifts (measured up to pH 8.8, at 38 degrees) of Czeta and Cgamma of the 3 tyrosine residues yields crude pKalpha values of 9.5 and 10 for Tyr-23 and one of the other tyrosines, respectively. The 3rd tyrosine residue does not exhibit titration behavior.
...
PMID:Studies of individual carbon sites of hen egg white lysozyme by natural abundance carbon 13 nuclear magnetic resonance spectroscopy. Assignment of the nonprotonated aromatic carbon resonances to specific residues in the sequence. 1 62

It is shown that natural abundance 13C NMR spectroscopy can be used to determine the structures and relative amounts of chemically modified forms of a histidine residue of a peptide or protein. The unfractionated product of the reaction of N alpha-acetyl-L-histidine with bromoacetate yields four resonances of nonprotonated aromatic carbons. These resonances are assigned (on a one-to-one basis) to C gamma of the intact amino acid, the two monocarboxymethylated derivatives (at N delta1 and N epsilon2), and the dicarboxymethylated derivative. The effect of pH on the chemical shift of C gamma is characteristic for each of the four species. This property is used to study the carboxymethylation of His-15 of hen egg white lysozyme upon treatment with iodoacetate. With the use of various reaction conditions, His 15 is carboxymethylated in detectable quantities only at N epsilon2. The spectra of the various reaction mixtures indicate which conditions are best for maximizing the yield of this derivative. A comparison of the spectrum of chromatographically pure [N epsilon2-carboxymethylhistidine-15]lysozyme with that of the intact protein indicates that the chemical modification does not significantly affect the conformation of the protein (at least in the regions of all aromatic amino acid residues).
...
PMID:Studies of chemically modified histidine residues of proteins by carbon 13 nuclear magnetic resonance spectroscopy. Reaction of hen egg white lysozyme with iodoacetate. 3 2

Hen egg white lysozyme has been prepared in which the C epsilon position of the single histidine residue is substituted by a deuterium atom as a nondisturbing stable isotope probe. The deuterium nuclear magnetic resonance (2H NMR) spectrum in H2O shows a broad resonance (500--1000 Hz) due to the histidine deuteron and a sharp signal from residual HOD. The line width of the deuterium signal increases with pH, reflecting the self-association of lysozyme which is known to involve this histidine [shindo, H., Cohen, J.S., & Rupley, J. A. (1977) Biochemistry 16, 3879]. Correlation times calculated from spin-spin relaxation times (T2) derived from the 2H widths indicate that His-15 is restricted in motion and that lysozyme is predominantly dimerized at pH 7.5. Controls carried out with [epsilon-2H]imidazole showed a small pH dependence of the spin-lattice relaxation time (T1), which parallels the 2H chemical shift change upon ionization of the imidazole. Similar results cannot generally be observed by proton nuclear magnetic resonance (1H NMR) because of paramagnetic relaxation due to trace metal ion impurities. The pH dependence of the 2H T1 values indicates a change in the 2H quadrupole coupling constant upon protonation of the imidazole ring.
...
PMID:Protein mobility and self-association by deuterium nuclear magnetic resonance. 3 94

The proton-decoupled 9.12 MHz 15N NMR spectra of 15N-labeled Bacillus subtilis, Bacillus licheniformis, Staphylococcus auresu, Streptococcus faecalis, and Micrococcus lysodeikticus intact cells, isolated cells walls, and cell wall digests have been examined. The general characteristics of Gram-positive bacteria 15N NMR spectra and described and spectral assignments are provided, which allow in vivo 15N NMR to be applied to a wide range of problems in bacterial cell wall research. The qualitative similarity of the intact cell and cell wall spectra found in each bacteria allowed the 15 N resonances observed in the proton broad-band noise-decoupled 15N NMR spectra of intact cells to be assigned to cell wall components. Each of the five Gram-positive bacteria displayed a unique set of cell wall 15N resonances, which reflected variations in the primary structure of peptidoglycans and the amounts of teichoic acid and teichuronic acid in the cell wall, as well as the dynamic properties of the cell wall polymers. Spectral assignments of cell wall 15 N resonances assigned to teichoic D-Ala residues, teichuronic acid and acetamido groups, and peptidoglycan acetamido, amide, peptide, and free amino groups have been made on the basis of specific isotopic labeling and dilution experiments, comparison of chemical shifts to literature values, determination of pH titration shifts, cell wall fractionation experiments, and comparative analysis of the cell wall lysozyme digest spectra in terms of the known primary sequences of peptide chains. All the peptidoglycan 15N peptide resonances observed in the intact cells and isolated cell walls could be accounted for by residues in the bridge or crossbar regions of the peptide chains, which indicated that only the cross-linking groups had a high degree of motional freedom. Thermal- and pH-induced conformational changes around the cross-linking D-Ala residues were detected in the B. licheniformis cell wall lysozyme digest products. Comparison of the proton broad-band noise-decoupled and gated decoupled intact cell and cell wall 15N spectra indicated that broad-band proton decoupling resulted in nulling of cytoplasmic resonances and enhancement of the cell wall resonances by the 15N [1H5 nuclear Overhauser effect.
...
PMID:Comparative in vivo nitrogen-15 nuclear magnetic resonance study of the cell wall components of five Gram-positive bacteria. 10 56

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

Natural abundance 13C Fourier transform NMR spectra (at 15.18 MHz, in 20-mm sample tubes) of aqueous native proteins yield numerous narrow single carbon resonances of nonprotonated aromatic carbons. Techniques for the assignment of these resonances are presented. Each technique is applied to one or more of the following proteins: ferricytochrome c from horse heart and Candida krusei, ferrocytochrome c and cyanoferricytochrome c from horse heart, lysozyme from hen egg white, cyanoferrimyoglobins from horse and sperm whale skeletal muscle, and carbon monoxide myoglobin from horse. In all of the protein spectra we have examined, methine aromatic carbons give rise to broad bands. Studies of the narrow resonances of nonprotonated aromatic carbons of proteins are facilitated by removal of these broad bands by means of the convolution-difference method, preferably from spectra recorded under conditions of noise-modulated off-resonance proton decoupling. We present a summary of the chemical shift ranges for the various types of nonprotonated aromatic carbons of amino acid residues and hemes of diamagnetic proteins, based on our results for hen egg white lysozyme, horse heart ferrocytochrome c, horse carbon monoxide myoglobin, and carbon monoxide hemoglobins from various species...
...
PMID:Studies of individual carbon sites of proteins in solution by natural abundance carbon 13 nuclear magnetic resonance spectroscopy. Strategies for assignments. 16 40

Deuteron spin-lattice relaxation times of specifically labelled methyl N-acetyl-D-glucosaminides associated to lysozyme were measured from 1H and 2H NMR spectra through bandshape analysis and FT inversion-recovery technique, respectively. Model calculations were carried out in order to assess the limits of the extreme narrowing approximation for the systems studied. Rotational correlation times of the acetamido methyl groups were analyzed in terms of anisotropic overall reorientation combined with internal rotation. The acetamido methyl group undergoes fast internal rotation in the alpha-glycoside complex about an axis nearly parallel with the major ellipsodial axis of lysozyme. More rotational freedom is likely to occur in the beta-glycoside complex.
...
PMID:Molecular dynamics through 2H spin-lattice relaxation time measurements with an enzyme-inhibitor complex: lysozyme and methyl N-acetyl glucosaminides. 88 Mar 36

The reaction of equimolar amounts of N-bromosuccinimide and hen egg-white lysozyme in acetate buffer, under the conditions of Hayashi et al. (Hayashi, K., Imoto, T., Funatsu, G., and Funatsu, M. (1965), J. Biochem. (Tokyo) 58, 227), yields a protein mixture that has a time-dependent 13C-NMR spectrum. The initial natural-abundance 13C-NMR spectrum indicates the presence of about equal amounts of [oxindolealanine-62]lysozyme and [delta1-acetoxytryptophan-62]lysozyme. The latter converts to [oxindolealanine-62]lysozyme with a half-life of about 2 days at 25 degrees C and pH 3.9. Two observations indicate that the source of the acetyl group of delta1-acetoxytryptophan-62 is the acetate buffer. First, the spectrum of a lysozyme sample treated with N-bromosuccinimide in the presence of [1-13C]acetate yields a very strong acetyl ester carbonyl resonance. The time dependence of the intensity of this resonance yields a half-life of 44 h for [delta1-acetoxytryptophan-62]lysozyme. Second, the initial natural-abundance 13C-NMR spectrum of a lysozyme sample treated with N-bromosuccinimide in the absence of acetate indicates essentially complete conversion of tryptophan-62 into oxindolealanine.
...
PMID:Formation of delta1-acetoxytryptophan-62 in the oxidation of tryptophan-62 of hen egg-white lysozyme by N-bromosuccinimide in acetate buffer. 98 61

Recently we developed methods for the construction of knowledge-based mean fields from a data base of known protein structures. As shown previously, this approach can be used to calculate ensembles of probable conformations for short fragments of polypeptide chains. Here we develop procedures for the assembly of short fragments to complete three-dimensional models of polypeptide chains. The amino acid sequence of a given protein is decomposed into all possible overlapping fragments of a given length, and an ensemble of probable conformations is calculated for each fragment. The fragments are assembled to a complete model by choosing appropriate conformations from the individual ensembles and by averaging over equivalent angles. Finally a consistent model is obtained by rebuilding the conformation from the average angles. From the average angles the local variability of the structure can be calculated, which is a useful criterion for the reliability of the model. The procedure is applied to the calculation of the local backbone conformations of myoglobin and lysozyme whose structures have been solved by X-ray analysis and thymosin beta 4, a polypeptide of 43 amino acid residues whose structure was recently investigated by NMR spectroscopy. We demonstrate that substantial fractions of the calculated local backbone conformations are similar to the experimentally determined structures.
...
PMID:Assembly of polypeptide and protein backbone conformations from low energy ensembles of short fragments: development of strategies and construction of models for myoglobin, lysozyme, and thymosin beta 4. 130 62


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

---