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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A study was made by histochemical methods of the activity of the enzymatic systems of macrophages from normal rabbits and those immunized with staphylococcus alpha-toxoid per se and infected with the strains of staphylococcus--producers of alpha-toxin or leukocydin. Immunization of rabbits was accompanied by a reduction in macrophages of the activity of the group of lysosomal enzymes and by an increase in the activity of the redox enzymes. In infection of "immune" macrophages with the living culture of the alpha-toxigenic strains the mentioned changes were more pronounced; no such changes were found after the infection with the leukocydin-active strain. The data obtained suggested that the lysosomal enzymes played a definite role in the process of phagocytosis.
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PMID:[Study of the functional activity of the macrophages of animals immunized with staphylococcal alpha-anatoxin]. 12 60

A highly-active staphylococcus alpha-hemolysin was obtained in a synthetic nutrient medium containing inorganic salts, vitamins, glucose and casamine acids, with fractional addition of glucose, histidine, and NaHCO3 solutions into the medium during cultivation. The intensity of alpha-toxin production was directly proportional to the initial concentration in the medium of casamine acids (within the range of 0.2--2.0%). The presence of lecithin in the medium (0.04%) accelerated the appearance of alpha-hemolysin, and then suppressed its production.
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PMID:[Production of staphylococcal alpha-hemolysin in a nutrient medium free of ballast substances]. 66 55

A model of transducin activation is constructed from its partial reactions (formation of metarhodopsin II, association, and dissociation of the rhodopsin-transducin complex). The kinetic equations of the model are solved both numerically and, for small photoactivation, analytically. From data on the partial reactions in vitro, rate and activation energy profile of amplified transducin turnover are modeled and compared with measured light-scattering signals of transducin activation in intact retinal rods. The data leave one free parameter, the rate of association between transducin and rhodopsin. Best fit is achieved for an activation energy of 35 kJ/mol, indicating lateral membrane diffusion of the proteins as its main determinant. The absolute value of the association rate is discussed in terms of the success of collisions to form the catalytic complex. It is greater than 30% for the intact retina and 10 times lower after permeabilization with staphylococcus aureus alpha-toxin. Dissociation rates for micromolar guanosinetriphosphale (GTP) (Kohl, B., and K. P. Hofmann, 1987. Biophys. J. 52:271-277) must be extrapolated linearly up to the millimolar range to explain the rapid transducin turnover in situ. This is interpreted by an unstable rhodopsin-transducin-GTP transient state. At the time of maximal turnover after a flash, the rate of activation is determined as 30, 120, 800, 2,500, and 4,000 activated transducins per photoactivated rhodopsin and second at 5, 10, 20, 30, 37 degrees C, respectively.
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PMID:Reaction rate and collisional efficiency of the rhodopsin-transducin system in intact retinal rods. 190 Dec 31

The antitoxic activity of leucocytic injection interferon I and immune interferon was shown in experimental erythrocyte hemolysis in the presence of staphylococcus alpha-toxin. The antitoxic effect was directly proportional to the interferon concentration in the medium and inversely proportional to the toxin concentration. Neutralization of the antiviral activity of leucocytic interferon did not lower its antitoxic effect. The highly purified and concentrated preparation of leucocytic injection interferon I and recombinant interferon had no antitoxic effect.
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PMID:[Antitoxic activity of interferon preparations]. 241 59

Staphylococcal alpha-toxin at subcytotoxic concentrations stimulated phosphatidylinositol turnover and arachidonic acid release in undifferentiated cultures of pheochromocytoma PC12 cells. Stimulation of phospholipase A2 but not C was dependent on extracellular calcium. Addition of staphylococcal alpha-toxin to PC12 cells caused a dose-dependent, biphasic increase in intracellular calcium measured by fura-2 fluorescence technique. Elevation of intracellular Ca2+ content occurred with a time course similar to those observed for stimulation of phospholipase A2. Alteration of membrane structure and formation of staphylococcal alpha-toxin pores facilitating an influx of Ca2+, represent the probable mechanisms by which phospholipases C and A2 are activated, respectively. These results suggest a possible involvement of Ca2+, phosphoinositides and arachidonic acid metabolites in the pathogenic action of staphylococcus alpha-toxin and caution against the general usage of this toxin as a permeabilizing agent to study stimulus-secretion coupling in secretory cells.
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PMID:Staphylococcus aureus alpha-toxin activates phospholipases and induces a Ca2+ influx in PC12 cells. 264 30

The effect of human blood serum from patients with purulent infections (sepsis, purulent resorptive fever) has been studied on the electrical and mechanical activities of isolated auricles of guinea pig. The intracellular resting potentials (RP), action potentials (AP) and isometric contractions elicited by electrical stimulation (1 Hz) were measured. The patient serum diluted by Tyrode solution (1:1) didn't change RP values and AP amplitude but caused a decrease in the AP plateau phase duration (P less than less than 0.05). In 75% cases a replacement of the healthy donor serum by the serum from patients caused a decrease in the contraction amplitude. This cardiodepressive effect was reversible: washing of the preparation by the control Tyrode solution or by the donor serum restored the normal contractility. These data were compared with those obtained in studying the action of staphylococcus alpha-toxin on a preparation of guinea pig myocardium]
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PMID:[Cardiodepressive effect of blood serum in severe forms of purulent infection]. 368 53

IgG Immunoglobulins can be differentiated into four subclasses with different structures and functions. Partial or complete defects of one or two subclasses can be related to an impaired immune defence. We describe four children with severe recurrent bacterial airway infections. Two children had developed bronchiectasia following recurrent bronchopulmonary inflammation. Prior to diagnosis of IgG subclass deficiency other common causes of recurrent airway infections were excluded. Defects of IgG 2 or IgG 4 antibodies as well as of both classes were found with compensatory elevation of IgG 1 and IgG 3. In repeated sputum cultures haemophilus influenzae and staphylococcus aureus were isolated. This might be due to an impaired antibody production against special antigens as alpha-toxin of staphylococcus or capsular polysaccharide of haemophilus influenzae. The four cases demonstrate that in children with severe recurrent airway infections including bronchiectasia and otitis media defects of IgG subclasses have to be considered. Diagnosis should be proved by repeated determinations of blood levels after exclusion of other common causes for infections. Diminution of IgG subclasses without clinical symptoms of airway infections is also possible. If diagnosis seems to be certain intravenous substitution with 7 s gammaglobulin beside symptomatic antibiotic therapy is recommended.
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PMID:[Defects of IgG subclasses as a cause of severe, recurrent respiratory tract infection]. 374 39

Native staphylococcus aureus alpha-toxin is secreted as a hydrophilic polypeptide chain of Mr 34,000. The presence of deoxycholate above the critical micellar concentration induced the toxin monomers to self-associate, forming ring or cylindrical oligomers. The oligomers were amphiphilic and bound detergent. In deoxycholate solution, the protein-detergent complexes exhibited a sedimentation coefficient of 10.4 S. A Mr of 238,700 was determined by ultracentrifugation analyses at sedimentation equilibrium. Because quantitative detergent-binding studies indicated a protein/detergent ratio of approximately 5:1 (wt/wt), the protein moiety in each protein-detergent complex was determined to be approximately Mr 200000, corresponding to a hexamer of the native molecule. The amphiphilic toxin hexamers were ultrastructurally indistinguishable from the cytolytic, annular toxin complexes that form on and in biological target membranes. They bound lipid and could be incorporated into artificial lecithin lipid vesicles. The transition of toxin protein molecules from a hydrophilic monomer to an amphiphilic oligomer through self-association has thus been shown to be inducible solely through contact of the native protein molecules with an appropriate amphiphilic substrate.
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PMID:Staphylococcal alpha-toxin: oligomerization of hydrophilic monomers to form amphiphilic hexamers induced through contact with deoxycholate detergent micelles. 627 4

The alpha-toxin (hemolysin) of Staphylococcus aureus is known to be an important determinant of pathogenicity although its precise role in the process of infection is not understood. In this study, the interaction of alpha-toxin with the human complement system was evaluated in terms of its effect on the opsonic activity of serum for S. aureus. Phagocytosis by human polymorphonuclear leukocytes was studied by measuring the uptake of preopsonized radiolabeled bacteria. It was found that alpha-toxin-treated serum had reduced opsonic activity and that this change was associated with complement consumption via the classical pathway. Levels of C3 to C9 were reduced in proportion to the amount of toxin added to the reaction mixture; levels of C2 were markedly reduced but those of factors B and D of the alternative pathway were unaltered in the presence of alpha-toxin. Heat-inactivated toxin, which had no hemolytic activity, also interacted with the complement system but with a significantly reduced effect. In addition, alpha-toxin behaved as a chemotaxinogen for polymorphonuclear leukocytes: human serum was activated by the toxin. These studies demonstrate that the interaction of staphylococcus alpha-toxin with human serum affects two important aspects of the host response to the staphylococcus.
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PMID:Biological effects of the interaction of staphylococcal alpha-toxin with human serum. 715 83

To solve the problems of biological safety of the cosmonaut on long-duration space mission and prediction of changes in macroorganism as a whole and constituting protein molecules under these conditions, it is important to study the influence of spaceflight factors (SFF) on microorganisms-carriers of modeled structures, protein molecules and pro- and eukaryotic genes in particular. Within the framework of scientific cooperation NAUKA-NASA, the authors proposed a model system of prokaryotic producers of pro- and eukaryotic proteins--staphylococcus alpha-toxin (SAT)--as a key protein in pathogenesis of staphylococcal infections, and human leukocytic interferon (HuIFN-alpha) as one of the homeostasis regulating proteins with well-studied structural and functional properties. Recombinant strains of E. coli with either a single or duplicated HuIFN-alpha 2b gene or other genes of the HuIFN-alpha family: HuIFN-alpha 8a, HuIFN-alpha 10a and HuIFN-alpha 14a were selected as producers of SAT and HuIFN-alpha. This biotechnologic system allows imitation and assessment of the SFF mutagenic effect both at the levels of genome of strain-carrier and gene-insertion and expressed CAT and HuIFN-alpha molecules including transcription, translation, assembly and post-translatory modifications of the target-protein. The developed methodology allows determination of highly mutable and conservative regions in the primary structure of a hypothetical protein associated with its functional activity, prediction of specific amino acid substitutes in these regions, and comparison of test calculations with a pool of natural mutations in the family of proteins under study. The structural/functional analysis of proteins and HuIFN-alpha genes made it possible to isolate and systematize functionally significant areas in the structure of hypothetical protein HuUFN-alpha, on the basis of which the most probable amino acid substitutions were prognosticated. This will present a possibility to identify expectable mutation events in HuIFN-alpha proteins, which so far have not been found in natural genes of the human interferon. Comparison of results of SFF modeling and space experiments aboard the International Space Station with monitoring of HuIFN-alpha mutant forms will help estimation of the extent of influence of the spaceflight factors on evolution of protein molecules.
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PMID:[Development of approaches to studying the structural and functional organization of protein molecules aboard the International space station]. 1181 14


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