Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.25 (triphosphatase)
 1,529 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Net synthesis of adenosine 5'-triphosphate (ATP) in energy-depleted cells of Escherichia coli was observed when an inwardly directed protonmotive force was artificially imposed. In wild-type cells, ATP synthesis occurred whether the protonmotive force was dominated by the membrane potential (negative inside) or the pH gradient (alkaline inside). Formation of ATP did not occur unless the protonmotive force exceeded a value of 200 mV. Under these conditions, no ATP synthesis was found when cells were exposed to an inhibitor of the membrane-bound Ca2+- and Mg2+- stimulated adenosine triphosphatase (EC 3.6.1.3), dicyclohexylcarbodiimide, or to a proton conductor, carbonylcyanide-p-trifluoromethoxyphenyl-hydrazone. Adenosine triphosphatase-negative mutants failed to show ATP synthesis in response to either a membrane potential or a pH gradient. ATP synthesis driven by a protonmotive force was observed in a cytochrome-deficient mutant. These observations are consistent with the chemiosmotic hypothesis of Mitchell (1961, 1966, 1974).
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PMID:Protonmotive force as the source of energy for adenosine 5'-triphosphate synthesis in Escherichia coli. 0 27

The biological activity of 2,4,8-trichlorodibenzofuran (2,4,8-TCDF) was tested using 2 endpoints: (a) the promotion of enzyme-altered, preneoplastic foci initiated by diethylnitrosamine (DEN) in livers of weanling female Sprague-Dawley rats; and (b) the induction of aryl hydrocarbon (benzo[a]pyrene) hydroxylase (AHH), a marker for cytochrome P-4501 activity, in livers of adult female Sprague-Dawley rats and in H4IIEC3 rat hepatoma cells. When animals were treated with 200 or 500 mg/kg 2,4,8-TCDF 5 X weekly over 10 weeks after a single application of 10 mg/kg DNA, the higher dose of 2,4,8-TCDF had a promoting effect on the appearance of preneoplastic foci. Thus number and total area of foci deficient in adenosine-5'-triphosphatase were significantly increased by a factor of 1.6. 2,4,8-TCDF induced AHH-activities in 9000 X g supernatants of liver 2-3-fold, when rats were treated with 100-1000 mg/kg/day for 5 days and monooxygenase activities determined after another 3 days. The amounts of 2,4,8-TCDF required for inducing AHH activity in H4IIEC3 cells were 7 orders of magnitude higher than those of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). the results indicate that the 2,4,8-TCDF has a biological activity which is extremely low compared to that of 2,3,7,8-TCDD.
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PMID:Biological activity of 2,4,8-trichlorodibenzofuran: promotion of rat liver foci and induction of cytochrome P-450-dependent monooxygenases. 263 Dec 93