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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth of Clostridium perfringens was inhibited by compounds which dissipate or prevent the formation of electrochemical proton gradients. Membrane vesicles prepared from this organism exhibited Mg2+-dependent adenosine triphosphatase (ATPase) activity sensitive to N,N'-dicyclohexylcarbodiimide. Mg2+-ATPase activity was optimal of 50 degrees C, but no discrete pH optimum was observed. Adenosine triphosphate-dependent quenching of the fluorescence of the weak base quinacrine by everted membrane vesicles suggested that the Mg2+-ATPase is a proton pump capable of generating an electrochemical proton gradient. Adenosine triphosphate-dependent transport of Ca2+ by everted vesicles was sensitive to uncouplers and inhibitors of the Mg2+-ATPase.
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PMID:Properties and function of the proton-translocating adenosine triphosphatase of Clostridium perfringens. 4 Sep 63

Adenosine triphosphate (ATP) hydrolysis catalyzed by the plasma membrane (Na+,K+)ATPase isolated from several sources was inhibited by Mg+, provided that K+ and ATP were also present. Phosphorylation of the adenosine triphosphatase (ATPase) by ATP and by inorganic phosphate was also inhibited, as was p-nitrophenyl phosphatase activity. (Ethylenedinitrilo)tetraacetic acid (EDTA) and catecholamines protected from and reversed the inhibition of ATP hydrolysis by Mg2+, K+ and ATP. EDTA was protected by chelation of Mg2+ but catecholamines acted by some other mechanism. The specificities of various nucleotides as inhibitors (in conjunction with Mg2+ and K+) and as substrates for the (Na+, K+) ATPase were strikingly different. ATP, ADP, beta,gamma-CH2-ATP and alpha,beta-CH2-ADP were active as inhibitors, whereas inosine, cytidine, uridine, and guanosine triphosphates (ITP, CTP, UTP, and GTP) and adenosine monophosphate (AMP) were not. On the other hand, ATP and CTP were substrates and beta,gamma-NH-ATP was a competitive inhibitor of ATP hydrolysis, but not an inhibitor in conjunction with Mg2+ and K+. The Ca2+-ATPase from sarcoplasmic reticulum and F1, the Mg2+-ATPase from the inner mitochondrial membrane, were also inhibited by Mg2+. Catecholamines reversed inhibition of the Ca2+-ATPase, but not that of F1.
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PMID:Reversible inhibition of (Na+, K+) ATPase by Mg2+, adenosine triphosphate, and K+. 13 42

Lead interferes with cellular energy metabolism by inhibiting ATP (Adenosine triphosphate) synthesis and hydrolysis. This study was conducted to determine in vitro effects of lead on Na+, K+-ATPase activity in four regions of adult rat brain: the cerebellum, the hippocampus, the frontal cortex and the brain stem. Male rats (Wistar strain) weighing 125-150 g were sacrificed, whole brain excised and the four regions were isolated. Each tissue was homogenized separately in sucrose (0.25 M) and imidazole (10 mM) buffer (pH 7.5) and P2 fraction was prepared by following established methods. The activity of ATPase was determined by measuring inorganic phosphate (Pi) liberated from ATP hydrolysis. The delineation of Na+, K+-activated component of ATPase was obtained by the difference between total ATPase and Mg2+-ATPase using 1 mM ouabain. The P2 fraction was incubated with 0, 5, 10, 25, 50 and 100 microM of lead at 37 degrees C for 10 min. The enzyme activity was expressed as micromoles of Pi liberated/mg protein/hr. The results indicated a concentration-dependent and region-specific response to lead. In vitro lead at 50 and 100 microM significantly inhibited ATPase activity in all regions of the brain. It was also observed that in the control rats, the enzyme activity was high in cerebellum and hippocampus regions of the brain. In vitro dithiothreitol (DTT) protected the enzyme activity from IC50 lead in four regions of brain. In cerebellum and hippocampus, a 5 microM DTT provided 100% protection against IC50 lead. These results suggest that lead interferes with the ion transport mechanism and cellular energy metabolism of the brain and this effect is region specific.
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PMID:In vitro effect of lead on Na+, K+-ATPase activity in different regions of adult rat brain. 1281 96