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 high-affinity calcium-binding sites of bovine and human alpha-lactalbumin as well as equine lysozyme were analyzed by 113Cd NMR spectroscopy. In the case of equine lysozyme, the addition of isotopically enriched 113Cd2+ results in a signal at delta = -75.9 ppm corresponding to the metal ion bound to the lone Ca(2+)-binding site of the protein. A peak at virtually the identical resonance position (delta = -77.1 ppm) was observed in the analogous experiment with bovine alpha-lactalbumin. In addition, a signal upfield of these (delta = -94.7 ppm) was observed for 113Cd(2+)-substituted human alpha-lactalbumin. The chemical shifts of these proteins are in the vicinity of those reported for other Ca(2+)-binding proteins. The field dependence of the 113Cd signals for all three proteins and bovine calmodulin were compared. At each field, the 113Cd signal linewidths for the alpha-lactalbumins and the lysozyme are somewhat broader than those observed for the EF-hand protein. In addition, the 113Cd linewidths for the lactalbumins and the lysozyme, especially bovine alpha-lactalbumin, increase dramatically with the square of the magnetic field strength, indicative of the presence of nuclear relaxation via chemical shift anisotropy and chemical exchange. The protein-bound 113Cd signals for the alpha-lactalbumins are also markedly affected by changes in the amount of K+ present, since Cd2+ and K+ can compete for occupation of the high-affinity Ca(2+)-site. Their linewidths also to some extent depend on the concentration of the protein itself.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cadmium-113 NMR studies of bovine and human alpha-lactalbumin and equine lysozyme. 762 32

Fourier transform infrared (FTIR) spectroscopy has been used to study temperature-induced structural changes which occur in albumin, immunoglobulin G, fibrinogen, lysozyme, alpha-lactalbumin, and ribonuclease S when dissolved in 2H2O. In order to analyze the data, a new method was developed in which the data were analyzed globally with the aid of a spectral model. Seven or eight bands were sufficient to fit the full data set of spectra ranging from 1420 to 1760 cm-1 with a root mean square error of 1-2% of the maximum. Subsequently, the estimated band amplitude curves which showed a sigmoidal progression with increasing temperature were (globally) fitted with a two-state thermodynamic model. In this way, information on structural changes as well as on the thermal stability of the proteins was obtained. In all proteins investigated, enhanced 1H-2H exchange occurred at temperatures well below the unfolding of the secondary structure. This was interpreted as a change in tertiary structure leading to enhanced solvent accessibility. In all the proteins investigated, except for ribonuclease S, an intermolecular beta-sheet band indicative of aggregation appeared concomitant with the denaturation of the secondary structure. The results are compared with data from other techniques and discussed in terms of local unfolding and folding intermediates.
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PMID:Temperature-induced changes in protein structures studied by Fourier transform infrared spectroscopy and global analysis. 765 5

Mammary Paget's disease has been said to result from epidermal spread by contiguity of primary intraductal carcinoma. To assess similar identity, we immunostained Paget's cells and underlying intraductal and/or invasive mammary carcinoma in 20 cases for cytokeratins, epithelial membrane antigen, gross cystic disease fluid protein-15, lysozyme, carcinoembryonic antigen, S100 protein, kappa-casein, and alpha-lactalbumin. Steroid receptor immunostain was positive in only one (5%) of the cases of Paget's disease and in two and four (approximately 15%) (for estrogen and progesterone receptor, respectively) of the cases of ductal carcinoma. In 18 patients (90%), the immunohistochemical profile was identical in Paget's cells and associated carcinoma for seven or more antigens. In one patient, there was a definite disparity in the antigenic profile; in another patient, this was dissimilar because of very focal staining in one site. The antigenic similarity between Paget's cells and underlying carcinoma in 18 (90%) of the cases of mammary Paget's disease suggested in favor of their common origin, ie, probably intraepidermal spread of ductal carcinoma. Origin from apocrine/eccrine structures, or multipotent cells in the epidermis, was suggested in a minority.
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PMID:Mammary Paget's disease and associated carcinoma. An immunohistochemical study. 768 Jan 94

In contrast to lysozymes, which undergo two-state thermal denaturation, the Ca(2+)-free form of the homologous alpha-lactalbumins forms an intermediate "molten globule" state. To understand this difference, we have produced a chimera of human lysozyme and bovine alpha-lactalbumin. In the synthetic gene of the former the sequence coding for amino acid residues 76-102 was replaced by that for bovine alpha-lactalbumin 72-97, which represents the Ca(2+)-binding loop and the central helix C. The chimeric protein, LYLA1, expressed in Saccharomyces cerevisiae was homogeneous on electrophoresis and mass spectrometry. Its Ca2+ binding constant was 2.50 (+/- 0.04) x 10(8) M-1, and its muramidase activity 10% of that of human lysozyme. One-dimensional NMR spectroscopy indicated the presence of a compact, well structured protein. From two-dimensional NMR spectra, main chain resonances for 118 of a total of 129 residues could be readily assigned. Nuclear Overhauser effect analysis and hydrogen-deuterium exchange measurements indicated the presence and persistence of all expected secondary structure elements. Thermal denaturation, measured by circular dichroism, showed a single transition temperature for the Ca2+ form at 90 degrees C, whereas unfolding of the apo form occurred at 73 degrees C in the near-UV and 81 degrees C in the far-UV range. These observations illustrate that by transplanting the central part of bovine alpha-lactalbumin, we have introduced into human lysozyme two important properties of alpha-lactalbumins, i.e. stabilization through Ca2+ binding and molten globule behavior.
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PMID:A Ca(2+)-binding chimera of human lysozyme and bovine alpha-lactalbumin that can form a molten globule. 773 86

A model was developed and implemented to aid in understanding and predicting the retention behaviour of proteins in ion-exchange chromatography. The model structures chosen were calcium-loaded and -depleted alpha-lactalbumin (ALC) and hen egg white lysozyme (HEWL) and a comparison was made with chromatographic measurements. A characteristic charge of -3.4 was found under the experimental conditions applied for both forms of ALC, and HEWL was not retained. The model explicitly considers all of the atoms, each being assigned a set of force field parameters. Because of the computational time necessary to include them, water molecules were not taken into account, but a sigmoidal function of the dielectric permittivity was introduced in the calculations. Interaction potential energies from bulk down to the contact were evaluated for each protein. The results were in qualitative agreement with those of the chromatographic experiments. It was possible to reproduce the difference in retention between both forms of ALC and also the behaviour of HEWL.
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PMID:Molecular approach to protein-polymer interactions in ion-exchange chromatography. 775 38

Clones encompassing the genes encoding alpha-lactalbumin and beta-lactoglobulin were isolated from a tammar wallaby genomic library, the exons localized using end-labeled oligonucleotides and the DNA sequences determined. The tammar beta-lactoglobulin gene has the same 7 exon-6 intron structure as the sheep homologue. Potential binding sites for mammary gland-specific transcription factors were identified, on the basis of similarity to sites in the sheep gene, in the promoter region of the tammar beta-lactoglobulin gene. The tammar gene encoding alpha-lactalbumin appears to contain four introns rather than three as are present in the eutherian homologues, or the evolutionarily related lysozyme gene. The additional intron appears to occur within the 5' noncoding region of the tammar gene.
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PMID:Exon organization and sequence of the genes encoding alpha-lactalbumin and beta-lactoglobulin from the tammar wallaby (Macropodidae, Marsupialia). 779 41

alpha-Lactalbumin is an abundant milk-specific calcium metalloprotein which has an evolutionary relationship to lysozyme. It modifies the substrate specificity of a Golgi galactosyltransferase by forming the lactose synthetase binary complex. Lactose, together with other sugars and diffusible ions, is responsible for the osmotic pressure of milk. To assess the involvement of alpha-lactalbumin in lactogenesis, alpha-lactalbumin-deficient mice were created by disrupting the gene by homologous recombination in embryonic stem cells. Homozygous mutant mice are viable and fertile but females cannot feed their offspring. They produce a highly viscous milk that pups appear to be unable to remove from the mammary gland. This milk is rich in fat and protein and is devoid of alpha-lactalbumin and lactose. The phenotype of heterozygous mice was found to be intermediate, with a 40% decrease in alpha-lactalbumin but only a 10-20% decrease in the lactose content of their milk compared with wild-type animals. These results emphasize the key function of alpha-lactalbumin in lactogenesis and open new opportunities to manipulate milk composition.
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PMID:Creation and phenotypic analysis of alpha-lactalbumin-deficient mice. 802 17

The potential relationship between serum PRL levels and protein composition of breast secretions was evaluated in 54 premenopausal nonlactating women during the luteal phase of their menstrual cycle. Women were classified into four groups according to the presence or absence of breast pathology and to the protein pattern of their breast secretions. Type I mammary fluids contain Zn-alpha 2-glycoprotein, apolipoprotein D, and gross cystic disease fluid protein-15, whereas Type II fluids are characterized by the presence of some milk proteins such as lactoferrin, lysozyme, and alpha-lactalbumin. Basal serum levels of PRL, as well as of progesterone, LH, FSH, TSH, T3, and T4 were within normal range, and no significant differences were found between the different groups of women under study. However, after a TRH stimulation test, the maximum PRL response was significantly higher (P < 0.02) in normal women with Type II secretions than in those with Type I (64 +/- 6.8 micrograms/L vs. 43.7 +/- 3.9 micrograms/L). Similarly, when PRL concentrations in patients with benign breast disease were considered, those with breast fluids containing milk proteins had a rise in PRL secretion after TRH stimulation significantly higher (P < 0.05) than those with fluids lacking these proteins (77.1 +/- 6.2 vs. 58.8 +/- 5.1 micrograms/L). These results indicate that the occurrence of milk proteins in breast secretions from nonlactating women is associated with an increase in serum PRL concentrations after TRH stimulation, and opens the possibility of using breast fluid protein analysis as a simple and noninvasive procedure for studies on the putative role of PRL in the development of benign and malignant breast diseases.
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PMID:Relationship between serum prolactin levels and protein composition of breast secretions in nonlactating women. 804 72

The complete unfolding of a protein involves the disruption of non-covalent intramolecular interactions within the protein and the subsequent hydration of the backbone and amino acid side-chains. The magnitude of the thermodynamic parameters associated with this process is known accurately for a growing number of globular proteins for which high-resolution structures are also available. The existence of this database of structural and thermodynamic information has facilitated the development of statistical procedures aimed at quantifying the relationships existing between protein structure and the thermodynamic parameters of folding/unfolding. Under some conditions proteins do not unfold completely, giving rise to states (commonly known as molten globules) in which the molecule retains some secondary structure and remains in a compact configuration after denaturation. This phenomenon is reflected in the thermodynamics of the process. Depending on the nature of the residual structure that exists after denaturation, the observed enthalpy, entropy and heat capacity changes will deviate in a particular and predictable way from the values expected for complete unfolding. For several proteins, these deviations have been shown to exhibit similar characteristics, suggesting that their equilibrium folding intermediates exhibit some common structural features. Employing empirically derived structure-energetic relationships, it is possible to identify in the native structure of the protein those regions with the higher probability of being structured in equilibrium partly folded states. In this work, a thermodynamic search algorithm aimed at identifying the structural determinants of the molten globule state has been applied to six globular proteins; alpha-lactalbumin, barnase, IIIGlc, interleukin-1 beta, phage T4 lysozyme and phage 434 repressor. Remarkably, the structural features of the predicted equilibrium intermediates coincide to a large extent with the known structural features of the corresponding intermediates determined by NMR hydrogen-exchange experiments.
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PMID:Structure based prediction of protein folding intermediates. 807 72

1. Proteins in human milk and Rhesus monkey milk have been compared by FPLC gel filtration and anion exchange chromatography, SDS-Polyacrylamide gel electrophoresis, nitrogen and protein determination. 2. Mature Rhesus milk is higher in protein concentration (15-20 mg/ml) than human milk (8-9 mg/ml). 3. Non-Protein nitrogen is 6-13% in Rhesus milk but 25-30% in human milk. 4. Secretory IgA, lactoferrin, serum albumin, alpha-lactalbumin and lysozyme are present in Rhesus milk, but at a lower concentration than in human milk. 5. The casein subunit pattern is more complex in Rhesus milk compared to human milk. 6. The ratio of whey proteins to casein is similar in both milks (approximately 60/40). 7. A protein with a M(r) of 21,600 is a major component in monkey whey but is not found in human milk.
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PMID:Protein composition of rhesus monkey milk: comparison to human milk. 809 84


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