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)

An arachidonic acid-stimulated Ser/Thr phosphatase activity was detected in soluble extracts prepared from rat pituitary clonal GH4C1 cells, rat or bovine brain, and bovine heart. The enzyme activity was purified to homogeneity from bovine brain as a monomer with a Mr of 63,000 and a specific activity of 32 nmol of Pi released per min/mg of protein when assayed in the presence of 10 microM phosphocasein in the absence of lipid. Arachidonic acid stimulated activity 4-14-fold, with half-maximal stimulation at 50-100 microM, when assayed in the presence of a variety of phosphosubstrates including casein, reduced carboxamidomethylated and maleylated lysozyme, myelin basic protein, and histone. Oleic acid, linoleic acid, and palmitoleic acid also stimulated activity; however, saturated fatty acids and alcohol or methyl ester derivatives of fatty acids did not significantly affect activity. The lipid-stimulated phosphatase was identified as the bovine equivalent of protein phosphatase 5 or a closely related homolog by sequence analysis of proteolytic fragments generated from the purified enzyme. When recombinant rat protein phosphatase 5 was expressed as a cleavable glutathione S-transferase fusion protein, the affinity-purified thrombin-cleaved enzyme exhibited a specific activity and sensitivity to arachidonic acid similar to those of the purified bovine brain enzyme. These results suggest that protein phosphatase 5 may be regulated in vivo by a lipid second messenger or another endogenous activator.
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PMID:Purification of a fatty acid-stimulated protein-serine/threonine phosphatase from bovine brain and its identification as a homolog of protein phosphatase 5. 927 97

For eleven films of various water-soluble alpha-, beta-, alpha-/beta-, and alpha-+beta-proteins, the amide-proton exchange, initiated by exposure of the protein film to 2H2O, has been monitored using infrared spectroscopy. The approach to obtain the kinetics of exchange for four different classes of amide protons, correlating to the different secondary structure types, has been described in detail in the preceding paper. In this work the more general applicability of the approach is illustrated by testing it for different types of proteins. The results obtained are shown not only to be comparable to reported time-resolved nuclear magnetic resonance data (as in the case of myoglobin, phospholipase A2, lysozyme, and cytochrome c), or to the more qualitative data obtained by neutron diffraction (trypsin, ribonuclease S, papain, and subtilisin BPN'), but the infrared approach us also provides with quantitative detailed insight on the distribution of exchange rate constants at the submolecular level of proteins, too complex to be studied by other techniques, as for tetrameric hemoglobin, and of proteins in which exchange is too fast to be detected by these other techniques, as is shown in this work for alpha-casein and apocytochrome c.
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PMID:Amide-proton exchange of water-soluble proteins of different structural classes studied at the submolecular level by infrared spectroscopy. 935 29

Cell-permeant peptidyl aldehydes and diazomethylketones are frequently utilized as inhibitors of regulatory intracellular proteases. In the present study the specificities of several peptidyl inhibitors for purified human mu-calpain and 20 S proteasome were investigated. Acetyl-LLnL aldehyde, acetyl-LLM aldehyde, carbobenzyloxy-LLnV aldehyde (ZLLnVal), and carbobenzyloxy-LLY-diazomethyl ketone produced half-maximum inhibition of the caseinolytic activity of mu-calpain at concentrations of 1-5 x 10(-7) M. In contrast, only ZLLnVal was a reasonably potent inhibitor of the caseinolytic activity of 20 S proteasome, producing 50% inhibition at 10(-5) M. The other inhibitors were at least 10-fold less potent, producing substantial inhibition only at near saturating concentrations in the assay buffer. Further studies with ZLLnVal demonstrated that its inhibition of the proteasome was independent of casein concentration over a 25-fold range. Proteolysis of calpastatin or lysozyme by the proteasome was half-maximally inhibited by 4 and 22 microM ZLLnVal, respectively. Thus, while other studies have shown that ZLLnVal is a potent inhibitor of the hydrophobic peptidase activity of the proteasome, it appears to be a much weaker inhibitor of its proteinase activity. The ability of the cell permeant peptidyl inhibitors to inhibit growth of the yeast Saccharomyces cerevisiae was studied because this organism expresses proteasome but not calpains. Concentrations of ZLLnVal as high as 200 microM had no detectable effect on growth rates of overnight cultures. However, yeast cell lysates prepared from these cultures contained 2 microM ZLLnVal, an amount which should have been sufficient to fully inhibit hydrophobic peptidase activity of yeast proteasome. Degradation of ubiquitinylated proteins in yeast extracts by endogenous proteasome was likewise sensitive only to high concentrations of ZLLnVal. The higher sensitivity of the proteinase activity of calpains to inhibition by the cell permeant inhibitors suggests that calpain-like activities may be targets of these inhibitors in animal cells.
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PMID:Specificities of cell permeant peptidyl inhibitors for the proteinase activities of mu-calpain and the 20 S proteasome. 936 65

The behavior of the model proteins, lysozyme, myoglobin, and beta-casein, pretreated in urea and/or dithiothreitol, at air/solution interfaces was studied by surface pressure-area techniques. The data suggested that in the absence of pretreatments the globular proteins are only partially unfolded at the interfaces. The interfacial activity was enhanced by the pretreatment (lysozyme in 8 M urea with 0.2 M dithiothreitol and myoglobin in 8 M urea). The interfacial activity of casein, a random-coil type protein, was not influenced by the pretreatment (8 M urea), as it readily and completely unfolds at the interfaces. The unfolding of globular proteins at the interfaces is apparently restricted by both disulfide and noncovalent bonds. Pretreatment can relax those restrictions, resulting in more complete interfacial unfolding. Copyright 1998 Academic Press. Copyright 1998Academic Press
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PMID:Behavior of Model Proteins, Pretreated in Urea and/or Dithiothreitol, at Air/Solution Interfaces 946 42

Kiwifruit (Actinidia chinensis) contains abundant protease, actinidin, and two possible components which were named A1 and A2. However, a comparison of the two components has not been thoroughly conducted. We have previously shown the presence of six proteases named KP1, KP2, KP3, KP4, KP5 and KP6 in kiwifruit, and that each purified kiwifruit protease was chromatographically pure. It was also indicated that the two representative components, KP4 and KP6, must be A1 and A2. To establish whether or not the two proteases, KP4 and KP6, have the same specificity in proteolytic activity, their enzymatic properties were compared. Between the two proteases, differences in substrate specificity against several protein-substrates (casein, gelatin, collagen, ovalbumin and bovine serum albumin) were not observed by digestion-product analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The kinetic parameters of KP4 against N-alpha-carbobenzoxyl-lysine p-nitrophenyl esters were different from those of KP6. The pH-activity profiles of KP4 and KP6 against S-3-trimethylaminopropyl-lysozyme, a wide-pH range soluble substrate, and N-alpha-carbobenzoxyl-lysine p-nitrophenyl esters were different.
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PMID:Enzymatic properties, substrate specificities and pH-activity profiles of two kiwifruit proteases. 950 43

In the common brushtail possum (Trichosurus vulpecula) lactation lasts for 200 days and consists of two distinct phases. Milk composition changes dramatically between phase 2 and 3, which correspond to early and late lactation respectively (phase 1 corresponds to pregnancy). RNA expression patterns have been established for eight major milk protein genes throughout lactation in possum mammary glands. The levels of mRNA expressed from two genes, encoding the early and late lactation proteins, were differentially regulated during lactation, with peak RNA levels occurring in phase 2 and 3 of lactation respectively. Expression of these two RNA transcripts did not overlap, and neither gene was expressed at significant levels between days 116 to 125, suggesting that the transition from phase 2 to phase 3 of lactation occurs at this time. The level of lysozyme, alpha-lactalbumin and trichosurin mRNA increased in phase 3 of lactation, whereas the levels of beta-lactoglobulin, alpha-casein and beta-casein mRNA remained constant throughout lactation. In the non-suckled gland, expression of milk protein genes was greatly reduced by day 6 of lactation. In conclusion, the early and late lactation protein genes are good markers for phase 2 and 3 of lactation, with the transition between these phases occurring around day 120 of lactation in the possum.
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PMID:Differential expression of milk protein genes during lactation in the common brushtail possum (Trichosurus vulpecula). 951 80

The electrophoretic protein profile and residue levels of selected persistent insecticides were investigated in 160 mother's milk samples representing 20 different locations in Egypt. Nine major protein bands were detected in all of the samples. These protein bands were designated as lactoferrin, albumin, SIgA heavy chain, casein I, casein II, SIgA light chain, casein III, lysozyme and alpha-lactalbumin. Residue levels of DDT and its metabolites as well as lindane and its other hexachlorocyclohexane isomers were determined using electron capture gas chromatography and confirmed by gas chromatography/mass spectrometric analysis. Samples containing relatively higher residue levels of the DDT group (DDT, DDE and DDD) showed significant effects on the levels of lysozyme and alpha-lactalbumin bands relative to samples with low or no residue levels. On the other hand, the casein subunits were mostly affected by the residue levels of hexachlorocyclohexane isomers (alpha, beta, gamma and delta isomers). The two patterns showed characteristic dose response correlation suggesting that the protein profile of human milk may serve as a quick biomarker for exposure to persistent insecticides.
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PMID:Mother's milk protein profile, a possible biomarker for human exposure to persistent insecticides. 983 Jan 30

In an earlier publication by Chattoraj et al. [Biophysical Chemistry 63 (1996) 37], a generalized equation for standard free energy of (delta G0) interaction of surfactant, inorganic salts and aqueous solvent with protein, forming a single phase has been deduced on strict thermodynamic grounds. In the present paper, this equation has been utilized to calculate delta G0 in kilojoules per kilogram of different proteins for the change of bulk surfactant activity from zero to unity in the mole fraction scale. Values of binding interactions of CTAB, MTAB, DTAB and SDS to BSA, beta-lactoglobulin, gelatin, casein, myosin, lysozyme and their binary and ternary mixtures had already been determined in this laboratory at different surfactant concentrations, pH, ionic strength and temperature using an equilibrium dialysis technique. Values of delta G0 for saturated protein-surfactant complexes as well as unsaturated complexes are found to be equal. delta G0 is also found to vary linearly with maximum moles of surfactants bound to a kilogram of protein or protein mixture and the slope of this linear plot represents standard free energy delta G0B for the transfer of 1 mol of surfactant from the bulk for binding reaction with protein; -delta G0 values for different systems vary widely and the order of their magnitudes represents relative affinities of surfactants to proteins. Magnitude of -delta G0B on the other hand varies within a narrow range of 32-37 kJ/mol of surfactant. For interaction of SDS with BSA, close to the CMC, values of delta G0 are very high due to the formation of micelles of protein-bound surfactants. Values of delta G0 for negative binding of inorganic salts to proteins and protein mixtures have been evaluated using our generalized equation in which excess binding values of water and salts have been calculated from the data obtained from our previous isopiestic experiments. delta G0 values in these cases are positive due to the excess hydration of proteins. Negative values of delta G0 in surfactant interaction and positive values of delta G0 for hydration of proteins in the presence of neutral salts represent relative affinities of proteins for solute and solvent since in all cases, the reference state for delta G0 is the unit mole fraction of solute in the aqueous phase.
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PMID:Standard free energies of binding of solute to proteins in aqueous medium. Part 2. Analysis of data obtained from equilibrium dialysis and isopiestic experiments. 1020 94

When an electrochemical method is tentatively applied for N-alkylation of proteins, some Maillard reactions occur on the counter electrode. A low level of reductive N-alkylation of casein was obtained on a cathodic electrode, but the method unfortunately remains poorly efficacious in comparison with those using a hydride donor such as sodium cyanoborohydride. Electroassisted reductive N-alkylation is suitable only for basic proteins such as histones or lysozyme. For other proteins, an alternative consists of either methylating carboxylic residues to increase the value of their isoelectric pH or coating them with a cationic detergent.
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PMID:Electrochemical modifications of proteins. 1. Glycitolation. 1055 71

The separation of drug enantiomers using proteins as the chiral selectors in capillary electrophoresis (CE) is considered in this review. The proteins used include albumins such as bovine serum albumin, human serum albumin and serum albumins from other species, glycoproteins such as alpha1-acid glycoprotein, crude ovomucoid, ovoglycoprotein, avidin and riboflavin binding protein, enzymes such as fungal cellulase, cellobiohydrolase I, pepsin and lysozyme and other proteins such as casein, human serum transferrin and ovotransferrin. Protein-based CE is carried out in two modes: in one proteins are immobilized or adsorbed within the capillary, or protein-immobilized silica gels are packed into the capillary (affinity capillary electrochromatography mode), and in the other proteins are dissolved in the running buffer (affinity CE mode). Furthermore, the advantages and limitations of the two modes and the factors affecting the chiral separations of various drugs by protein-based CE are discussed.
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PMID:Enantiomer separation of drugs by capillary electrophoresis using proteins as chiral selectors. 1083 46


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