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)

Staphylococcus epidermidis peptidoglycans solubilized by sonication or lysozyme digestion, and synthetic peptidoglycan analogs such as HSA-carboxymethyl-Gly-L-Ala-L-Ala-D-Ala-D-Ala (HSA-pentapeptide) or L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala (pentapeptide) have been labeled with 125I and tested for their applicability in the radioactive antigen binding assay. Use of radioiodinated Staph. epidermidis peptidoglycans was found to be considerably impeded by the presence of at least 2 different antigenic sites on such molecules, the pentapeptide and the glycan determinant. Application of labeled HSA-pentapeptide was limited by the necessity to use PEG for precipitation of Ag-Ab-complexes and by short linear potions of binding curves. However, the synthetic pentapeptide hapten, radioiodinated by the active ester method of BOLTON and HUNTER, proved to be a most useful regent for the selective measurement of pentapeptide antibody. Inhibition studies indicated that the immunological specificity of the labeled hapten was retained. Pentapeptide binding curves were linear from 15-500 g/ml of antibody. Generally, there was good agreement between pentapeptide antibody concentrations measured by radioimmunoassay and quantitative precipitation.
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PMID:Measurement of peptidoglycan antibodies by a radioimmunoassay. 5 37

Absorption and fluorescence measurements of purified hypericin (HY) were made in various media. Photosensitization of two aqueous systems was investigated: resealed red blood cell membranes (ghosts) and hen lysozyme (Lys). Solubilization of HY by ghost membranes was shown by means of diffuse reflectance spectroscopy. Visible light irradiation of the ghosts incorporating HY led to lipid peroxidation with evidence of singlet oxygen involvement. A binding model applicable for insoluble ligands is indicative of strong HY binding to HSA. The HY-HSA complex photosensitized inactivation of Lys. The pseudo-first-order reaction kinetics with protection by azide ion are consistent with a Type II mechanism mediated by singlet oxygen. The results are discussed in the context of the HY photodynamic and antiretroviral activities.
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PMID:Photosensitization of aqueous model systems by hypericin. 173 34

The deposition of antigens and immune complexes (IC) in the renal glomerulus is charge-dependent. The demonstration that molecules of net anionic charge, but with discrete positively charged regions, exhibit affinity for the glomerular basement membrane (GBM) extends this concept. Charge hybrid (polar) molecules were constructed by covalently coupling small polycations (lysozyme or linear poly-L-lysine chains with a mean of 17 and 20 residues) to larger polyanions (ovalbumin or human serum albumin (HSA]. Although the products were of overall net anionic charge they still bound to glomerular structures. Immunofluorescence studies performed after i.v. injection of the samples into rats revealed that HSA:poly-L-lysine had the highest affinity. Radioisotopic measurements showed uptake of HSA:poly-L-lysine to be a function of the number of lysine residues; binding of HSA:poly-L-lysine20 was 2.5 times higher than HSA:poly-L-lysine17 (P less than 0.01). Prior injection of a small competing polycation (polyethyleneimine 1200) reduced uptake of HSA:poly-L-lysine by 75%, indicating the charge-based nature of the interaction. HSA:poly-L-lysine20 alone was effectively eliminated from the glomeruli within 72 h. Administration of HSA:poly-L-lysine followed by anti-HSA antibody induced immune complex formation in the capillary wall, giving rise to a granular immunofluorescence pattern and discrete subendothelial and subepithelial deposits. Molecules with polar structure do occur naturally and may contribute to immune complex formation in glomerulonephritis.
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PMID:Surface charge distribution is a determinant of antigen deposition in the renal glomerulus: studies employing 'charge-hybrid' molecules. 174 55

Regulation of B lymphocyte development by the mu-membrane (mu m) and delta-membrane (delta m) heavy chains of Ig was examined in an Ig transgenic mouse model. Mice were bred on a common C57BL/6 (B6) background, and expressed rearranged and hypermutated heavy and light chain transgenes encoding high-affinity receptors for the foreign antigen hen egg lysozyme (HEL). At no stage were they exposed to HEL. Variation of the Ig heavy chain construct yielded four different types of Ig transgenic mice in which developing B lineage cells either expressed mu m and delta m in the normal physiological sequence (mu m then mu m + delta m), or produced mu m alone, delta m alone or mu m + delta m from the onset of heavy chain expression in the bone marrow. Immature B220low, HSAhigh and mature B220high, HSAlow B cells were produced in all mice regardless of their developmental pattern of mu m and delta m expression. However, production of immature B cells was most efficient when mu m heavy chain was expressed alone during early B cell development. Thus expression of delta m during this period either in the presence or absence of mu m resulted in a 2- to 3-fold reduction in the numbers of immature B cells in the spleen as well as altered levels of surface B220 and HSA on these cells in spleen and bone marrow respectively. By contrast, normal maturationally regulated expression of delta m led to the presence of increased numbers of mature B cells in the spleen and lengthened the average lifespan of these cells as determined by in vivo incorporation of 5-bromo-2'-deoxyuridine. These results pointed to selective effects of mu m and delta m heavy chains on regulation of the early and late stages of B cell development respectively, and provided a rational basis for co-expression of mu m and delta m as well as the delayed expression of delta m during normal B cell development.
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PMID:Differential regulation of early and late stages of B lymphocyte development by the mu and delta membrane heavy chains of Ig. 769 8

We constructed a plasmid that directs the synthesis and secretion of hepatitis B virus (HBV) surface antigen (HBsAg) particles by Saccharomyces cerevisiae. This plasmid contains a proteinase-resistant HBsAg M (M-P31c) gene fused at its 5'-terminus with a chicken-lysozyme signal peptide (C-SIG) gene, which is placed under the yeast GLD (glyceraldehyde-3-phosphate dehydrogenase gene) promoter. The products encoded by the "C-SIG+M-P31c" (LM-P31c) gene were synthesized and assembled themselves into HBsAg particles in yeast cells, and the particles were released into the medium along with poly-HSA (polymerized human serum albumin) binding activity. The HBsAg particles purified from the medium were very similar in density (1.19 g cm-3), size (19.2 +/- 0.8 nm in diameter) and shape (sphere) to human-plasma-derived HBsAg particles. When several sec (temperature-sensitive secretion-defective) mutants were used as host cells, the release of HBsAg particles into the medium was blocked at 37 degrees C but not at 25 degrees C, indicating that the HBsAg particles are exported through the normal yeast secretion pathway. To our knowledge, this is the first report that yeast cells are capable of secreting particles into the medium.
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PMID:Saccharomyces cerevisiae can release hepatitis B virus surface antigen (HBsAg) particles into the medium by its secretory apparatus. 776 88

Classical model system: Poly-L-glutamic acid (Poly-Glu) was investigated in a disordered coil state (at pH-7.0) and in helix state (at pH 2.0) by Rayleigh scattering of Moessbauer radiation technique. Consider that the coil state of poly-Glu models unfolded (random coil) state and alpha-helix state models the fluctuating secondary structure (during consequent folding of protein) comparative analysis of dynamical properties of poly-Glu in different states with dynamical properties of different proteins in native state (alpha-helical myoglobin and HSA, partially beta-sheet lysozyme) and in intermediate (molten globule) state (alpha-lactalbumin) was performed. This comparison bring some surprising results: native alpha-helical proteins behave itself close to random coil, native partially beta-sheet protein behaves close to fluctuating secondary structure (alpha-helix) and the dynamic behaviour of molten globule state (partially beta-sheet alpha-lactalbumin) is not different from those behaviour of lysozyme and much more rigid than native alpha-helical proteins. As a result one cannot exclude the possibility that folding process and dynamical properties at different steps of the folding are very different for alpha-helical and beta-sheet proteins.
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PMID:[Comparison of dynamic properties of various globular proteins and polyglutamic acid in alpha-helical and coil states. Rayleigh scattering of Mossbauer radiation data]. 918

A poly(vinyl alcohol) (PVA) coated particulate perfluoropolymer (FEP) support has been functionalised with ion-exchange groups for use in ion-exchange chromatography of proteins. Anion-exchange (DEAE and Q) and cation-exchange (SP) groups were introduced to PVA-FEP which had previously been activated using cyanuric chloride. The equilibrium adsorption capacities of SP-PVA-FEP were 31.8 and 25.2 mg ml-1 for lysozyme and IgG respectively while for DEAE-PVA-FEP, the equilibrium adsorption capacities were 14.9 and 9.7 mg ml-1 for beta-lactoglobulin and HSA respectively. The equilibrium adsorption capacities for Q-PVA-FEP were determined to be 17.2 and 13.5 mg ml-1 for beta-lactoglobulin and HSA respectively. Experiments carried out to investigate the resolving power of materials showed that both SP and Q-PVA-FEP were able to resolve proteins with only small differences in their isoelectric points and that this resolution could be maintained at a flow-rate of 1500 cm h-1. SP-PVA-FEP was used to purify lysozyme from egg whites where a 50-fold purification, to homogeneity, was achieved in 98% yield. The anion exchanger, Q-PVA-FEP could be used to purify G6PDH from a clarified homogenate of bakers' yeast 14.3-fold in 81% yield.
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PMID:Preparation and use of ion-exchange chromatographic supports based on perfluoropolymers. 922 92

Poly(styrene-divinylbenzene) (PS-DVB) chromatography matrices, CG1000sd 20-50 microns (TosoHaas), PLRP4000s 15-25 microns, PLRP4000s 50-70 microns (Polymer Laboratories) have been modified by the adsorption and crosslinking of poly(vinyl alcohol) (PVA) to create a matrix suitable for the attachment of dye ligands. The adsorption capacities of lysozyme and HSA on these Procion Yellow HE-3G dyed PVA modified PS-DVB matrices were measured at various flow-rates and the capacities were compared with a Procion Yellow HE-3G dyed OH-activated POROS 20, 20-micron matrix (PerSeptive Biosystems). The adsorption of small proteins was not hindered by the smaller pores of the CG1000sd beads, but as protein size increased, and at high flow-rates, a high mass transfer rate became more dependent on large pore size and small particle diameter.
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PMID:Modification of polystyrenic matrices for the purification of proteins. III. Effects of poly(vinyl alcohol) modification on the characteristics of protein adsorption on conventional and perfusion polystyrenic matrices. 928 79

Ultrafiltration is an attractive process for virus removal from bioproducts owing to its high throughput as well as the fact that the operation is carried out under ambient conditions (damage to proteins is highly limited). The principal concern regarding the adoption of conventional ultrafiltration membranes for virus removal is the possibility of the virus passing through abnormally large pores or surface imperfections on the membrane surface. The chief principle behind the present work is to pretreat the membrane by blocking the abnormally large pores using latex particles. Experimental work was conducted to validate this pretreatment using the bacteriophage phi x 174 as a model virus. The results attained were highly encouraging. Different sizes of latex particles were tested by treating a 100 KD molecular weight cut-off membrane, and the transmission of phage (suspended in buffer) through this membrane assessed. In the absence of any particle pretreatment, a virus clearance of 4.78 log reduction value was observed for this membrane. The transmission of phage through the membrane could be reduced by an order of magnitude using 0.11 micron latex particles, or two orders of magnitude using a combination of 0.11 and 0.50 micron particles. The application of latex particles did not hinder the transport of protein through the 100 KD membrane. Protein sieving coefficients obtained using this membrane were 91%, 16% and 2%, for lysozyme, HSA and IgG, respectively.
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PMID:Virus removal from bioproducts using ultrafiltration membranes modified with latex particle pretreatment. 976 96

The noncovalent binding of selected phenolic compounds (chlorogenic-, ferulic-, gallic acid, quercetin, rutin, and isoquercetin) to proteins (HSA, BSA, soy glycinin, and lysozyme) was studied by an indirect method applying the quenching of intrinsic tryptophan fluorescence. From the data obtained, the binding constants were calculated by nonlinear regression (one site binding; y = Bx/k + x). It has been reported that tannins inhibit human salivary amylase and that these complexes may reduce the development of cariogenic plaques. Further, amylase contains two tryptophan residues in its active site. Therefore, in a second part of the study involving 31 human subjects, evidence was sought for noncovalent interactions between the phenols of green tea and saliva proteins as measured by the fluorescence intensity. Amylase activity was determined before and after the addition of green tea to saliva of 31 subjects. Forty percent of the subjects showed an increase in amylase activity contrary to studies reporting only a decrease in activity. The interactions of tannin with amylase result in a decrease of its activity. It still remains to be elucidated why amylase does not react uniformly under conditions of applying green tea to saliva. Further, in terms of using phenols as caries inhibitors this finding should be of importance.
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PMID:Determining the binding affinities of phenolic compounds to proteins by quenching of the intrinsic tryptophan fluorescence. 1683 69


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