Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The functions of the chromaffin vesicles are reflected in their molecular organization. They contain large amounts of water-soluble proteins and ATP, which act in concert with catecholamines to form a stable storage pool. The vesicles contain an ATP-driven catecholamine transport system that enables the vesicles to take up dopamine, the precursor to NE, and to recover amines that leak out of the granules. The transport system appears to be coupled to the ATPase activity of the vesicle membranes and to include an amine carrier. The enzyme DBH is present as a soluble protein within the vesicle and as a component of the membrane. However, substrates can be acted upon only after they have been transported into the vesicle. During secretion the vesicle membrane fuses with the plasma membrane, but little is known about how this occurs.
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PMID:Functional organization of adrenal chromaffin vesicles. 115 35

delta-Hexachlorocyclohexane (delta-HCH) is shown to be 30-fold more potent as a positive inotropic agent with rat atrial strips compared with lindane (gamma-HCH). Threshold and ED50 values for enhanced contractile force at a pacing frequency of 0.5 Hz are less than 1 microM and 2.2 microM for delta-HCH and 40 microM and 63 microM for gamma-HCH, respectively. Contracture developed in atria exposed to greater than 4 microM delta-HCH (ED50 = 11 microM) but not in atria exposed to gamma-HCH. Uptake and release of Ca++ measured from actively loaded cardiac sarcoplasmic reticulum (SR) vesicles is measured with antipyrylazo III. Although delta-HCH (30 microM) decreases Ca(++)-dependent ATPase by 20%, it does not significantly alter Ca++ loading in the presence of ruthenium red. Addition of delta-HCH (5-50 microM) after loading is complete causes rapid, dose-dependent release of Ca++ from SR. Ca++ release induced by delta-HCH is markedly stereoselective. Compared with gamma-HCH (50 microM), delta-HCH (50 microM) induces a nearly 20-fold higher initial rate of Ca++ release (4.3 nmol of Ca++/mg/sec). Studies with [3H]ryanodine demonstrate that delta-HCH sharply inhibits Ca(++)- or daunorubicin-activated radioligand binding (IC50 = 37 and 25 microM, respectively, logit slope = 2). Inhibition of [3H]ryanodine-binding by delta-HCH is stereoselective inasmuch as IC50 values for alpha, beta and gamma isomers are greater than 100 microM. The delta-HCH modified Ca++ channel appears to proceed by a noncompetitive mechanism (reducing Bmax in equilibrium experiments) with respect to the conformationally sensitive binding site for [3H]ryanodine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stereoselective modulation of ryanodine-sensitive calcium channels by the delta isomer of hexachlorocyclohexane (delta-HCH). 138 81

Residues of organochlorine pesticides were monitored in the muscles of Bolti fish Tilapia zillii, the crab Lupa pelagicus and sediment samples collected from El Temsah lake around Ismailia using gas liquid chromatography. The beta isomer of hexachlorocyclohexane (beta.HCH) was the most dominant compound detected in all samples, followed by P, P-DDE and P, P-DDT. Results showed the crab to contain higher concentrations of organochlorine in comparison to concentrations detected in fish muscles. The In-vitro effect of the residues extracted from fish, and crab on the mitochondrial brain and liver ATPase of the New Zealand white rabbit Orcytolagus cuniculus was also studied. Residues of organochlorine pesticides have induced activation in the ATPase enzyme system of both brain and liver. The mixtures of organochlorine residues of both fish and crab were able to activate liver ATPase more than brain ATPase. The present study was conducted to extrapolate possible effects incurred on man if consumed such food.
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PMID:Residues of organochlorine pesticides in fish, crab and sediment from El Temsah Lake, Suez Canal, Egypt and their effect on mitochondrial ATPase of the New Zealand white rabbit. 183 60

In vitro investigations of the influence of lindane and its metabolites were performed on microsomal and mitochondrial ATPases from liver, kidney and brain of rat and mouse. The microsomal Na+-K+-ATPases in rat liver were inhibited by the tested substances. An increase of activity was observed only with 2.5 X 10(-5) M gamma-HCH. Effects on the microsomal Na+-K+-ATPase from kidney and brain of rat were also indicated. The mitochondrial enzyme in rat liver was stimulated by all the compounds tested at concentrations of 10(-4) M - 10(-2) M. The effects on mitochondrial enzymes from kidney and brain varied in dependence on the tested substances. In the microsomes and mitochondria of mouse an influence on the Na+-K+-ATPases similar to the effects on the preparations from organs of rat was evident.
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PMID:[The influence of lindane and lindane metabolites on microsomal and mitochondrial ATPase in vitro]. 241 97

The behavior of hyperplastic nodules following an in vivo short-term screening test for hepatocarcinogens was studied. Rats were injected ip with 200 mg/kg body weight of diethylnitrosamine (DEN), given basal diet containing 200 ppm of N-2-fluorenylacetamide (2-FAA) (group 1), 1000 ppm of the alpha-isomer of 1,2,3,4,5,6,-hexachlorocyclohexane (alpha-BHC) (group 2) or basal diet (group 3) from week 3 to week 8, and then given basal diet and tap water. They were subjected to partial hepatectomy at the end of week 3. Animals were killed at weeks 4, 6, 8, 10, 20, 30, 40, and 50. A significant disappearance of hyperplastic nodules following the cessation of carcinogen treatment was observed in group 1, but was not evident in groups 2 and 3. With gamma-glutamyltranspeptidase (GGTase) as a positive marker and adenosine triphosphatase (ATPase) as a negative marker, hyperplastic nodules were classified into 3 different phenotypic categories, i.e., (1) GGTase-positive and ATPase-negative, (2) GGTase-positive, and (3) ATPase-negative. The percentages of GGTase-positive and ATPase-negative hyperplastic nodules were almost 80 approximately 90% in group 1 and 70 approximately 80% in groups 2 and 3. Some of the hyperplastic nodules were necrotic from week 8 in groups 1 and 2, and from week 20 in group 3. Subsequently, the numbers of necrotic hyperplastic nodules increased with time. Hepatocellular carcinomas were found at weeks 30, 40, and 50 in group 1, and at weeks 40 and 50 in group 2. Significantly higher incidences of cancer were found in group 1 than in group 2. The hepatocellular carcinomas were also classified enzyme-histochemically into 3 different phenotypic categories as for hyperplastic nodules, but the percentage (20%) of GGTase-positive and ATPase-negative hepatocellular carcinomas was significantly lower than that (70 approximately 90%) of GGTase-positive and ATPase-negative hyperplastic nodules in each group.
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PMID:A sequential quantitative study of the reversibility or irreversibility of liver hyperplastic nodules in rats exposed to hepatocarcinogens. 611 91

The inhibitory potencies of BHC isomers against Na+-K+- ATPase, yeast growth and nerve conduction of the American cockroach were determined. The insecticidal and neuroexcitatory activities of a number of analogs with the same configuration as lindane in which some chlorine atoms had been replaced by other substituents were also examined against American cockroaches. The structure-activity relationships and the mode of action of lindane and its analogs were discussed. Their metabolic fate was studied extensively in vivo as well as in vitro. The critical step in the biodegradation of lindane is the cleavage of C-H bonds which we found by utilizing the isotope effect of hexadeuterated lindane.
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PMID:Biochemical toxicology of lindane and its analogs. 618 95

Gamma-HCH (lindane) administered for long durations is reported to cause toxic cardiovascular effects. Present study was carried out to assess the changes in cardiovascular activity and cellular calcium homeostatic mechanisms in rats administered 3 mg kg-1 day-1 of gamma-HCH p.o. for 6 weeks. The changes in electrocardiogram were marked by a decrease in R-R interval and the amplitude of the P wave by 53% and 50%, respectively. The amplitude of R and T waves was increased by 65% and 58%, respectively. Calcium-45 influx was increased in atrial trabeculae (33%) and in papillary muscle (10%). The plasma calcium concentration was increased (32%) and Ca,K-ATPase activity in heart was decreased (50%). It is suggested on the basis of these findings that cellular calcium homeostatic mechanisms are involved in the cardiovascular effects of gamma-HCH administered chronically in rats.
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PMID:Possible role of calcium in the cardiovascular effects of prolonged administration of gamma-HCH (lindane) in rats. 759 91

The changes in biochemical constituents of rat erythrocyte membranes were observed after a single ip exposure to 300 mg commercial HCH/kg body weight (one-third of the LD50). The phospholipid:cholesterol ratio was altered, and there were changes in the activities of the membrane-bound enzymes ATPase and acetylcholinesterase. The phospholipid content was increased while cholesterol and ATPase and acetylcholinesterase activities were significantly decreased. The erythrocytes also showed morphological changes (cell deformity and echinocyte formation).
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PMID:Biochemical and structural alterations in rat erythrocytes due to hexachlorocyclohexane exposure. 768 30

1. Hexachlorocyclohexane (HCH), an organochlorine pesticide having hydrophobic molecule is known to act on membranes. HCH mediated alterations in erythrocyte membrane occur through disorganization of the lipid bilayer. Therefore the changes in erythrocyte membrane fluidity, osmotic fragility and certain membrane bound enzymes were studied. Administration of HCH (technical) to rats at 5 mg/kg, orally, 5 days a week for 1, 2 and 3 months caused marked increase in erythrocyte membrane fluidity, osmotic fragility and decrease in levels of Na+, K(+)-ATPase, acetylcholinesterase in erythrocytes and glutathione in blood. 2. These changes indicate that HCH adversely affects membrane structure and function.
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PMID:Alterations in rat erythrocyte membrane due to hexachlorocyclohexane (technical) exposure. 986 22

The terminase enzyme from bacteriophage lambda is composed of two viral proteins (gpA, 73.2 kDa; gpNu1, 20.4 kDa) and is responsible for packaging viral DNA into the confines of an empty procapsid. We are interested in the genetic, biochemical, and biophysical properties of DNA packaging in phage lambda and, in particular, the nucleoprotein complexes involved in these processes. These studies require the routine purification of large quantities of wild-type and mutant proteins in order to probe the molecular mechanism of DNA packaging. Toward this end, we have constructed a hexahistidine (hexa-His)-tagged terminase holoenzyme as well as hexa-His-tagged gpNu1 and gpA subunits. We present a simple, one-step purification scheme for the purification of large quantities of the holoenzyme and the individual subunits directly from the crude cell lysate. Importantly, we have developed a method to purify the highly insoluble gpNu1 subunit from inclusion bodies in a single step. Hexa-His terminase holoenzyme is functional in vivo and possesses steady-state and single-turnover ATPase activity that is indistinguishable from wild-type enzyme. The nuclease activity of the modified holoenzyme is near wild type, but the reaction exhibits a greater dependence on Escherichia coli integration host factor, a result that is mirrored in vivo. These results suggest that the hexa-His-tagged holoenzyme possesses a mild DNA-binding defect that is masked, at least in part, by integration host factor. The mild defect in hexa-His terminase holoenzyme is more significant in the isolated gpA-hexa-His subunit that does not appear to bind DNA. Moreover, whereas the hexa-His-tagged gpNu1 subunit may be reconstituted into a holoenzyme complex with wild-type catalytic activities, gpA-hexa-His is impaired in its interactions with the gpNu1 subunit of the enzyme. The results reported here underscore that a complete biochemical characterization of the effects of purification tags on enzyme function must be performed prior to their use in mechanistic studies.
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PMID:Cloning, expression, and biochemical characterization of hexahistidine-tagged terminase proteins. 1033 15


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