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)

Endocytosis in the renal tubular cell is a permanent process serving the role of saving nitrogen from plasma peptides that are continuously cleared away by kidney glomerulus. Since small proteins appear in urine after strenuous exercise, it was hypothesized that renal ischemia impairs the tubular endocytic reabsorption of proteins. The aim of this paper is to describe a simple in vitro model of renal endocytosis and to use it in studies of endocytic metabolic requirements. The results show that rabbit renal proximal tubules in suspension are able to take up 125I-lysozyme, as well as RITC-lactalbumin. The fluorescent protein was taken up only by the ends of the everted tubule fragments, and accumulated into intracellular vesicles, demonstrating the luminal pathway of endocytosis. The amount of 125I-lysozyme taken up was equivalent to that taken up by isolated perfused tubules (Nielsen et al. (1986) Am. J. Physiol. 251, F822-F830). Anoxia decreased 12-fold the intracellular accumulation of 125I-lysozyme; however, the time-course of inhibition shows that only the late steps of endocytic accumulation are energy-dependent. Substrate deprivation studies suggest a specific role of glucose to sustain endocytosis. Lastly, renal uptake of 125I-lysozyme was shown to be strongly depressed by chloroquine, an alkalinizing agent of endosomes and lysosomes. We conclude that (1) renal tubules in suspension are a satisfactory model for endocytic studies in kidney; (2) suppressing oxygen and substrate supplies to kidney impairs endocytic tubular reabsorption of proteins.
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PMID:Protein endocytosis by a kidney tubule suspension: metabolic requirements. 829 19

In order to correlate between spectroscopic and structural changes in a protein, the environment of Trp 135 in T4 lysozyme was deliberately perturbed by the replacement of Gln 105 with alanine (Q105A), glycine (Q105G), and glutamic acid (Q105E). In wild-type lysozyme, Trp 135 is buried, but the indole nitrogen is hydrogen-bonded to the side-chain of Gln 105. In the Q105G and Q105A mutant structures, the indole nitrogen becomes accessible to solvent. Crystallographic analysis shows that the structures of all of the mutants are similar to wild-type. There are, however, distinct rearrangements of the local solvent structure in response to the new side-chains. There are also small but significant changes in the relative orientations of the two domains of the protein that appear to result from a series of small, concerted movements of side-chains adjacent to residue 105. Evaluation of the fluorescence and phosphorescence of the mutant proteins in terms of their observed three-dimensional structures shows that large spectral changes do not necessarily imply large changes in structure or in static solvent accessibility. Increases in polar relaxation about the excited state of tryptophan may be the result of only small increases in local dynamics or solvent exposure. 1H-NMR was also used to monitor the effects of the substitutions on Trp 138. In Q105E, but not in Q105G, Q105A and WT, the H epsilon chemical shift of Trp 138 is very pH-dependent, apparently reflecting the titration of Glu 105 which has a spectroscopically determined pKa of 6.0. The elevation of the pKa of Glu 105 in Q105E is also reflected in the pH dependence of the stability of this mutant.
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PMID:Perturbation of Trp 138 in T4 lysozyme by mutations at Gln 105 used to correlate changes in structure, stability, solvation, and spectroscopic properties. 846 Jan 10

A 39-year-old woman was consulted to our hospital because of renal failure on October 1992. A chest X-ray showed no abnormal shadow. Subsequently, she was under conservative treatment until December 1993, when she began to notice clouded vision. The iridocyclitis in both eyes was diagnosed by a ophthalmologist. She was admitted to our hospital for the purpose of a renal biopsy. Laboratory tests revealed renal failure: a creatinine clearance of 24.5 ml/min, a serum level of creatinine of 3.2 mg/ml and blood urea nitrogen of 38.7 mg/dl. The angiotensin converting enzyme was 17.6 IU/ml (normal 8.3 approximately 21.4 IU/ml), but lysozyme was 49.5 micrograms/ml (normal 5.0 approximately 10.2). Mantoux's reaction was negative. 57Ga scintigram showed abnormal uptakes on eyes, bilateral salivary gland, both thighs, both kidneys, and in a part of lung field. A percutaneous renal biopsy revealed non-caseating histiocytic granulomas with diffuse infiltration of lymphocytes and neutrophils into interstitium. Glomeruli were ischemic and mild endocapillary proliferations with pericapsular fibrosis were seen. Both of transbronchial lung biopsy (TBLB) and skin biopsy also revealed non-caseating histiocytic granulomas. Oral administration of prednisolone, 40 mg/day, improved the level of serum creatinine and lysozyme. Sarcoidosis is a granulomatous disease of unknown etiology that may involve any organ or tissue of the body. The clinical picture dominating in adults is the one with pulmonary and mediastinal lymph node involvement, eye and skin lesions. Although the renal involvement were rarely encountered, the present case showed that the renal failure was one of the most important clinical feature in patient with sarcoidosis.
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PMID:[A case of sarcoidosis with renal failure as the main manifestation in granulomatous interstitial nephritis]. 856 2

Aspergillus niger has been used successfully to secrete proteins labelled with 13C and/or 15N to a specific activity of > 99% for high resolution NMR analysis. In the case of a heterologous protein, hen egg-white lysozyme, 15N single-labelled and 13C, 15N double-labelled forms were secreted at yields of 100-200 mg l-1 by optimising the type of carbon source used and the ratio of carbon to nitrogen. Another protein, the glucoamylase starch-binding domain from A. niger, was also produced as the 15N single-labelled form at 20-40 mg l-1.
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PMID:Efficient production from Aspergillus niger of a heterologous protein and an individual protein domain, heavy isotope-labelled, for structure-function analysis. 867 88

The thermal denaturation of lysozyme was studied at pH 2.50 and 6.00 in aqueous solutions of ammonium (NH4Cl and NH4Br) and tetraalkylammonium halides (Me4NCl, Me4NBr, Et4NBr, Pr4NBr, Bu4NBr) using high-sensitivity differential scanning calorimetry. The transition temperature, heat capacity, enthalpy, entropy and free energy of denaturation have been determined by a least-squares fit of the excess heat capacity data to the two-state model. Ammonium and tetraalkylammonium halides (except Me4NCl and NH4Cl at high concentrations at pH 6.00) are found to destabilize lysozyme and the destabilization increases with increasing concentration and alkyl chain length. However, NH4Cl and Me4NCl act as stabilizers at high concentrations at pH 6.00. Results are discussed in terms of electrostatic and hydrophobic interactions. The stabilization of lysozyme by NH4Cl and Me4NCl can be attributed to the charge on the quaternary nitrogen atom while destabilization in tetraalkylammonium halides solution is due to the interaction between hydrophobic molecules of the medium and the hydrophobic parts of the protein.
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PMID:Differential scanning calorimetric studies on the effect of ammonium and tetraalkylammonium halides on the stability of lysozyme. 886 36

After the recent discovery of a ribonuclease A unfolding intermediate [Kiefhaber, T., et al. (1995) Nature 375, 513-515], we investigated the unfolding pathway of hen egg white lysozyme. At pH* 4.00 with D2O at 10 degrees C and 6 M guanidinium chloride, unfolding shows a single, slow kinetic phase, with a relaxation time of 3300 s when monitored by circular dichroism (CD). Exchange of the tryptophan indole nitrogen protons shows that buried Trp residues 123, 111, and 108 lose tight packing and become solvent-exposed simultaneously, with a mean relaxation time of 3300 s, similar to the CD-monitored unfolding rate. Unfolding monitored by Trp fluorescence shows, moreover, that 90% of the amplitude change occurs in a slow phase, with a relaxation time of 2400 s. Faster-unfolding phases with minor amplitudes are detected by Trp indole hydrogen exchange and by fluorescence. It is likely that these changes are caused by Trp 62 and Trp 63, active site residues which are not buried in the hydrophobic core. Lysozyme unfolding was further monitored by the histidine 15 C epsilon1 proton, which gives resolved lines for the native and unfolded species in one-dimensional 1H-NMR spectra. The majority of the unfolding reaction, 70%, occurs in a slow phase with a relaxation time of 3600 s, but there is also a rapid unfolding phase; 30% of the His 15 C epsilon1 proton resonance intensity is found at the unfolded chemical shift within tens of seconds after the start of unfolding. The amplitude of the rapid unfolding phase increases proportionally with the concentration of GdmCl denaturant present. These results show that a partially buried residue of lysozyme, histidine 15, takes part in forming an unfolding intermediate similar to the one observed earlier for valine 63 in ribonuclease A. The tryptophan side chains buried in the hydrophobic core of lysoyzme, in contrast, do not participate in forming the unfolding intermediate, as judged by proton chemical shifts. The buried tryptophan residues of dihydrofolate reductase, monitored by 19F-NMR, do participate in forming an unfolding intermediate [Hoeltzli, S. D., & Frieden, C. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 9318-9322]; the difference between that study and ours may reside in the greater sensitivity of 19F to the detection of motional differences.
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PMID:Characterization of the unfolding pathway of hen egg white lysozyme. 906 98

A poly(styrene-divinylbenzene) (PSDVB) chromatography matrix, CG1000-sd (TosoHaas), has been modified using poly(vinyl alcohol) (PVA) to create a matrix suitable for the attachment of functional groups for the selective purification of proteins. The characteristics of the modified matrix have been studied using a BET nitrogen adsorption/desorption technique and it has been found that the adsorption of PVA results in the bead micropores being filled whilst the bead macropores are left essentially unaltered. There was no protein adsorption onto the modified matrices. A dye ligand (Procion Blue MX-R) has been covalently attached to PVA-PSDVB matrix and the lysozyme capacities of the PVA-PSDVB matrix have been determined. The matrix compares well with commercial Blue Sepharose Fast Flow, an affinity matrix on cross-linked agarose. The dye-PVA-PSDVB matrix is stable when subjected to sanitisation with sodium hydroxide.
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PMID:Modification of polystyrenic matrices for the purification of proteins. Effect of the adsorption of poly(vinyl alcohol) on the characteristics of poly(styrene-divinylbenzene) beads for use in affinity chromatography. 918 73

Proteinase 3, the antigen commonly recognized by classical anti-neutrophil cytoplasmic antibodies (cANCA) in patients with Wegener's granulomatosis was purified from neutrophil azurophilic granules. Proteinase 3, a serine protease with an apparent molecular mass of 29 kDa, was extracted with Triton X-100 from the azurophilic granule fraction of neutrophils after nitrogen bomb cavitation and Percoll gradient centrifugation. Anion exchange chromatography removed many proteins, which were bound to the column. The unbound proteins, which contained most of the proteinase 3, were then separated by gel filtration. All chromatography steps were done in the presence of detergent. SDS polyacrylamide gel electrophoresis of this preparation only revealed three bands migrating closely together at the position of a 29-31 kDa protein, characteristic of proteinase 3. Affinity-purified polyclonal antibodies raised against proteinase 3 were used for immunoblotting studies and demonstrated that the purified protein was proteinase 3. Antibodies to elastase, cathepsin G, myeloperoxidase, lactoferrin or lysozyme did not react in ELISA assays with the isolated protein. The proteinase 3 prepared by this procedure was found to be suitable as an antigen for detecting PR3-ANCA both in ELISA and in immunoblotting experiments.
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PMID:A simple high yield procedure for purification of human proteinase 3, the main molecular target of cANCA. 932 66

Based on first principles and molecular mechanics calculations, we conclude that the mechanism of hevamine (a family 18 chitinase) involves an oxazoline ion intermediate stabilized by the neighboring C2' acetamido group. In this intermediate, the acetamido carbonyl oxygen atom forms a covalent bond to C1' of N-acetyl-glucosamine and has a transferred positive charge from the pyranose ring onto the acetamido nitrogen atom, leading to an anchimeric stabilization of 38.1 kcal/mol when docked with hevamine. This double displacement mechanism involving an oxazoline intermediate distinguishes the family 18 chitinase (which have one acidic residue near the active site) from family 19 chitinase and from hen egg-white lysozyme, which have two acidic residues near the active site. The structural and electronic properties of the oxazoline intermediate are similar to the known chitinase inhibitor allosamidin, suggesting that allosamidins act as transition state analogs of an oxazoline intermediate. Structural and electronic features of the oxazoline ion likely to be important in the design of new chitinase inhibitors are discussed.
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PMID:Substrate assistance in the mechanism of family 18 chitinases: theoretical studies of potential intermediates and inhibitors. 967 59

A nitrogen gas-based foam fractionation method was employed to separate model proteins, bovine serum albumin (BSA) and hen egg white lysozyme, from each other. Fractionation was characterized by the separation ratio and by recovery of proteins in the retentate as a function of the nominal pore size of the gas dispersion frit and solution conditions (pH and ionic strength). For binary mixtures of the proteins at pH 7.4, and ionic strength (mu) of 0.18 M, the recovery of lysozyme and the separation ratio were both dependent on the frit size employed to generate the foam. At low ionic strength (mu = 0.01 M), separation was only somewhat greater with the small pore size frits, although at values significantly lower than those found for high ionic strength. The diminished separations appear to be due to the only slight changes in recoveries observed for BSA and lysozyme.%Separation ratios of lysozyme from BSA in solutions either of high or low ionic strength were maximal at pH values equal to or less than the isoelectric point (pI) of BSA. Separation ratios were lower when foaming was carried out under low compared with high ionic strength. The recovery of lysozyme was enhanced by foaming from solutions of low pH and high ionic strength. Recoveries of BSA were greatest when the molecule was negatively charged. Electrical interactions between the positively charged lysozyme and negatively charged BSA may explain the diminished separation ratios and enhanced recoveries. Enzyme activity studies of lysozyme remaining in the retentate showed no change from prefoam activity.
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PMID:Foam fractionation of binary mixtures of lysozyme and albumin. 1082 28


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