• The Korean Journal of Physiology
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• v.10 no.1
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• pp.25-34
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• 1976

The action of serotonin on the sodium plus potassium activated ATPase activity in the rabbit red cell membrane has been investigated. The experiments were also designed to determine the mechanism of action of serotonin on the ATPase activity. The following results were obtained. 1) The NaK ATPase activity of rabbit red cell ghosts is stimulated by low concentration of serotonin but inhibited by higher concentration, and the concentration of serotonin for maximal activity is about 2mM. The pH optimum for the serotonin sensitive component is 8.0. 2) The activating effect of serotonin on the ATPase, with a given concentration of sodium in the medium, is increased by raising the potassium concentration but the ratio of activity is decreased. 3) The activating effect of serotonin on the ATPase, with a given concentration of potassium in the medium, is increased by raising the sodium concentration but the ratio of activity is decreased. 4) The ATPase activity is increased by small amounts of calcium but inhibited by larger amounts and the ratio of activity by serotonin is decreased by small amounts of calcium but increased by larger amounts. 5) The action of serotonin on the ATPase activity was not related to the amino group of lysine, the hydroxyl group of threonine, the carboxyl group of aspartic acid, or the imidazole group of histidine. 6) The action of serotonin on the ATPase activity is due to sulfhydryl group of the enzyme of NaK ATPase.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1724-1728
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• 2009

Severe acute respiratory syndrome coronavirus (SARS-CoV) helicase separates the double-stranded nucleic acids using the energy from ATP hydrolysis. We have measured ATPase activity of SARS-CoV helicase in the presence of various types of nucleic acids. Steady state ATPase analysis showed that poly(U) has two-times higher turnover number than poly(C) with lower Michaelis constant. When M13 single-stranded DNA is used as substrate, the Michaelis constant was about twenty-times lower than poly(U), whereas turnover numbers were similar. However, stimulation of ATPase activity was not observed in the presence of double-stranded DNA. pH dependent profiles of ATP hydrolysis with the helicase showed that the optimal ATPase activities were in a range of pH 6.2 ~ 6.6. In addition, ATP hydrolysis activity assays performed in the presence of various divalent cations exhibited that $Mg^{2+}$ stimulated the ATPase activity with the highest rate and $Mn^{2+}$ with about 40% rate as compared to the $Mg^{2+}$.

• The Korean Journal of Zoology
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• v.37 no.4
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• pp.531-537
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• 1994

Partial internal amino acid sequences of the 15S ATPase from chick skeletal muscle were determined and found to be identical to the corresponding regions of the Mg2+_ATPase from Xenopus laevis oocytes, that is a close homolog of N-ethvlmaleimide-sensitive factor (called NSF) in hamster and Sec18p in yeast, both of which are believed to plaN an essential role in vesicle fusion in secretory process. Thus, the 15S Arpase in chick skeletal muscle maw also belong to a protein family of the "vesicle fusion proteins". Unlike the Mg2'-Afpase with an isoelectric point (pl) of 5.5, however, the 15S Arpase was separated into four spots with pls of 4.9,6.4 and 6.9 upon analysis by twoiimensional gel electrophoresis. In addition, the anti-15S ATPase IgG was found to be capable of interacting with the 265 protease complex upon analysis by immunoprecipitation. Moreover, immunoblot analysis revealed that the anti-155 Arpase IgG recognizes three subunits, ko of which show the same mobilities as the 510-kDa subunit 4 and 48-kDa subunit 7 of the 26S protease complex that are known to contain a highly consented ATP-binding motif. These results surest that a common antigenic site, likely the consensus nucleotide-binding site, exists in the 15S ATPase and the 26S pretense complex and hence both the enzymes maw also be related ATPases.d ATPases.

• The Korean Journal of Zoology
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• v.18 no.4
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• pp.221-229
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• 1975

The effect of adenosine 3', 5'-cyclic monophosphate on the ATPase activity and on the active transport of Ca of the sarcoplasmic reticulum fragments of the rabbit skeletal muscle was studied. Cyclic AMP (cAMP) had no effect on the ATPase activity of the fragments (8,000 ~ 20,000 $\times$ G and 20,000 ~ 36,000 $\times$ G fractions). $N^6$, O^{2'} -Dibutyryl cAMP (DBcAMP) had either no effect on the activity. On the other hand, theophylline (1 mM) increased the activity by about 20%. The active uptake of Ca by the sarcoplasmic reticulum fragments was inhibited by the presence of 1$\times$$10^{-6}$ ~ 1 $\times$ $10^{-3}$M of cAMP. The presence of DBcAMP or theophylline also inhibited the uptake. It is, therefore, concluded that the Ca uptake of the sarcoplasmic reticulum seems to be controlled by cAMP.

• The Korean Journal of Pharmacology
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• v.26 no.1
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• pp.35-49
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• 1990

A highly purified $(Na^+,\;K^+)-ATPase$ from the rectal gland of Squalus acanthias and from the electric organ of Electrophorus electricus has been used to raise antibodies in rabbits. The 97,000 dalton catalytic subunit and glycoprotein derived from the rectal gland of spiny shark were also used as antigens. The two $(Na^+,\;K^+)-ATPase$ holoenzymes and the two shark subunits were antigenic. In Ouchterlony double diffusion experiments, these antibodies formed precipitation bands with their antigens. Antibodies prepared against the two subunits of shark holoenzyme also formed precipitation bands with their antigens and shark holoenzyme, but not with eel holoenzyme. These observations are in good agreement with inhibitory effect of these antibodies on the catalytic activity of $(Na^+,\;K^+)-ATPase$ both from the shark and the eel, since there is very little cross-reaction between the shark anticatalytic subunit antibodies and the eel holoenzyme. The maximum antibodies titer of the anticatalytic subunit antibodies is found to be 6 weeks after the initial single exposure to this antigen. Multiple injections of the antigen increased the antibody titer. However, the time required to produce the maximum antibody titer was approximately the same. These antibodies also inhibit catalytic activity of $(Na^+,\;K^+)-ATPase$ vesicles reconstituted by a slow dialysis of cholate after solubilization of the enzyme in a presonicated mixture of cholate and phospholipid. In these reconstituted $(Na^+,\;K^+)-ATPase$ vesicles, effects of these antibodies on the fluxes of $Na^+$, $Rb^+$, and $K^+$ were investigated. Control or preimmune serum had no effect on the influx of $^{22}Na^+$ or the efflux of $^{86}Rb^+$. Immunized sera against the shark $(Na^+,\;K^+)-ATPase$ holoenzyme, its glycoprotein or catalytic subunit did inhibit the influx of $^{22}Na^+$ and the efflux of $^{86}Rb^+$. It was also demonstrated that these antibodies inhibit the coupled counter-transport of $Na^+$ and $K^+$ as studied by means of dual labeling experiments. However, this inhibitory effect of the antibodies on transport of ions in the $(Na^+,\;K^+)-ATPase$ vesicles is manifested only on the portion of energy and temperature dependent alkali metal fluxes, not on the portion of ATP and ouabain insensitive ion movement. Simultaneous determination of effects of the antibodies on ion fluxes and vesicular catalytic activity indicates that an inhibition of active ion transport in reconstituted $(Na^+,\;K^+)-ATPase$ vesicles appears to be due to the inhibitory action of the antibodies on the enzymatic activity of $(Na^+,\;K^+)-ATPase$ molecules incorporated in the vesicles. These findings that the inhibitory effects of the antibodies specific to $(Na^+,\;K^+)-ATPase$ or to its subunits on ATP and temperature sensitive monovalent cation transport in parallel with the inhibitory effect of vesicular catalytic activity by these antibodies provide direct evidence that $(Na^+,\;K^+)-ATPase$ is the molecular machinery of active cation transport in this reconstituted $(Na^+,\;K^+)-ATPase$ vesicular system.

• Journal of Life Science
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• v.6 no.1
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• pp.1-5
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• 1996

Using differential hybridization, a cDNA clone was isolated fortuitously from Amaranthus viridis and sequenced. This nucleotide sequence exhibited 55.1% identity with vma6 which encodes the 36-kD subunit of the vacuolar proton transporting ATPase in Saccharmoyces cerevisiae. The predicted open reading frame encodes a protein of 221 amino acid sequence with a calculated molecular weight of 25,452 and reveals high levels of similarity with subunit D polypeptide of vacuolar H -ATP(e.g., 48.5, 52.1 and 49.3% identity to the vacuolar 36-kD chain of yeast, vacuolar 32-kD polypeptide IV of human and vacuolar 28-kD protein of bovine chromaffin granules, respectively). The hydropathy index computation revealed that this predicted protein is a peripheral protein. These results indicated that the predicted protein may play a sturctural role in the vaculor H -ATPase as does gamma subunit in V-type ATPase.

• The Korean Journal of Zoology
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• v.37 no.4
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• pp.524-530
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• 1994

An Arpase complex has been purified to apparent homogeniety from the extract of chick skeletal muscle using conventional column chromatographies and glycerol density gradient centrifugation. This eWe has a sedimentation coefficient of 15S as determined by the gradient centrifugation and therefore is referred to as the 15S ATPase. It behaves as a 600-kOa molecule upon gel filtration analysis using a Superose-6 column. However, the ATPase runs as a 95-kDa polvpeptide when analyzed by polvacrvlamide gel electrophoresis in the presence of sodium dodecyl sulfate. Thus, the Arpase is likely to consist of six identical subunits of 95 KDa. It has a Km value of 0.6 mM for ATP and is maximally active at pH 9.

• Archives of Pharmacal Research
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• v.24 no.3
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• pp.202-206
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• 2001

The effects of various sedative cyclopeptides and peptide alkaloids from the Zizyphus species on calmodulin-dependent $Ca^{2+}$ -ATPase and phosphodiesterase were Investigated. Calmodulin-induced activation of $Ca^{2+}$-ATPase was strongly inhibited by sanjoinine-A dialdehyde (IC_{50}$, 2.3$\mu\textrm{m}$), -Ah1 (IC_{50}$, 4.0$\mu\textrm{m}$), -A (IC, 4.6$\mu\textrm{m}$), and -G2 (IC_{50}$, 7.2$\mu\textrm{m}$), while calmodulin-induced activation of phosphodiesterase was strongly inhibited by both deachuine- S10 (IC_{50}$, 4.9$\mu\textrm{m}$) and sanjoinine-D (IC_{50}$, 9.0$\mu\textrm{m}$). The inhibitory activity of the various cyclopeptides and peptide alkaloids on $Ca^{2+}$-ATPase was found to correlate well with their Sedative activity.

• Archives of Pharmacal Research
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• v.9 no.1
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• pp.29-38
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• 1986

The effects of ginseng saponins on the sarcolemmal $Na^{+}$, $K^{+}$-ATPase were compared to gypsophila saponin, sodium dodecylsulfate (SDS), and Triton X-100 to elucidate whether the effects are due to the membrane distruption, using a highly enriched preparation of cardiac sarcolemma prepared from dog ventricular myocardium. About 26% and 29% of vesicles in the preparation, enriched in ouabain-sensitive $Na^{+}$, $K^{+}$-ATP ase, $\beta$-adrenergic and muscarinic receptors are rightside-out and inside-out orientation, respectively. Ginseng saponins (triol>total> diol) inhibited $Na^{+}$, $K^{+}$-ATP ase activity, $Na^{+}$, $K^{+}$-ATPase activity and [$^{3}$H]ouabain binding of sarcolemmal vesicles. However, gypsophila saponin, SDS (0.4$\mu$g/$\mu$g protein) and Triton X-100 (0.6 $\mu$g/$\mu$g protein) caused about 1.35 and 1.40-fold increase in $Na^{+}$, $K^{+}$-ATPase activity and [$^{3}$H] oubain binding, respectively. Especially, the activating effect of gypsophila saponin on membrane Na+, K+ ATPase was detected at gypsophila saponin to sarcolemmal protein ratios as high as 100. Low dose of ginseng saponin (3$\mu$g/$\mu$g protein) decreased the phosphorylation sites and the concentration of ouabain binding sites (Bmax) without affecting the turnover number and affinity for ouabain binding, while gypsophila saponin, SDS(0.4 ug/ug protein), ahd Triton X-100 (0.6$\mu$g/$\mu$g protein) increased the Bmax. The results suggest that ginseng saponins cause a decrease in the number of active sites by interacting directly with $Na^{+}$, $K^{+}$-ATPase before disruption of membrane barriers of sarcolemmal vesicles.

• Archives of Pharmacal Research
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• v.19 no.2
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• pp.126-131
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• 1996

The effects of various synthetic benzimidazole derivatives on gastric H^+/K^+$ATPase activity in vitro were examined. The results showed that the effects of substituents on the benzimidazole ring were not significant. However, replacement of sulfoxide connecting two ring systems to sulfide resulted in a completely inactive compound in vitro, suggesting the essential role of sulfoxide group in the inhibition. In addition, compounds with 5 or 6-membered oxacyclic substituents attached to the pyridine ring displayed the most effective inhibitory activity. Among these derivatives, AU-47 was the most potent, and detailed mechanistic studies with the compound were carried out. AU-47 inhibited gastricH^+/K^+$ATPase in a concentration and time dependent manner with 50% inhibition at $6\muM$. The presence of sulfhydryl reducing agents or substrate analogue protected H^+/K^+$ATPase from the inactivation. The inhibition by AU-47 was potentiated by acid pretreatment of the compound, suggesting the structural conversion of AU-47 into a more active intermediate which was favored in acidic condition. Consistent with in vitro results, AU-47 inhibited in vivo gastric acid secretion. The results suggest that AU47 is a relevant candidate for the development of new antiulcer agent.