• KSBB Journal
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• v.17 no.1
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• pp.59-62
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• 2002

The enzyme sensor for ATPase activity consisted of an immobilized membrane of two enzymes, purine nucloside phosphorylase (NP) and xanthine oxidase (XOD), and oxygen electrode. The $H^ +-ATPase $ rate of the plasma membranes increased by low root temperature. A cucumber and a pumpkin plasma membrane $H^ +-ATPase $$ activities measured by the proposed sensor system were in good agreement with the results obtained by a conventional UV spetrometer assay. One cycle of assay could be completed within 3 minutes.

• Microbiology and Biotechnology Letters
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• v.27 no.5
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• pp.354-358
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• 1999

In order to know the antifungal characteristics of saturated fatty acids having 6 to 12 carbons, their minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were estimated against Saccharomyces cerevisiae. Fatty acids from C6 to C11 exhibited increasing activity with chain length, but C12 fatty acid did not show activity at all. In relation to antifungal modes of actions, fatty acids investigated showed on inhibitory activity toward the plasma membrane H+-ATPase of Saccharomyces cerevisiae. Their inhibitions to the glucose-induced acidification and ATP hydrolysis caused by the proton pump were found to be in common wiht antifungal activities. At the test concentration of 1mM, hexanoic acid (C6) showed the lowest inhibition of about 30%, while undecanoic acid(C11) showed the strongest inhibition of over 90%. In addition, as seen with antifungal activity, the inhibitory activity of dodecanoic acid (C12) was suddenly reduced to less than 50%.

• Applied Biological Chemistry
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• v.46 no.2
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• pp.84-89
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• 2003

In order to find a chemical agent which is able to modulate the activity of $H^+-ATPase$, microsomal preparation was obtained from the root tissue of tomato plant and the effect of $La^{3+}$ was measured. The activities of plasma and vacuolar membrane $H^+-ATPase$ were analyzed by the inhibited activities using their specific inhibitors, vanadate and $NO_3-$, respectively. $La^{3+}$ inhibited microsomal ATPases in a dose-dependent manner and the inhibitory effect of $La^{3+}$ was suppressed by both vanadate and $NO_3-$, implying that $La^{3+}$ inhibits both plasma and vacuolar membrane $H^+-ATPase$. The Ki. values of $La^{3+}$which inhibit 50% of the activities of plasma and vacuolar membrane $H^+-ATPase$ were 57 and $78\;{\mu}M$, respectively. The $H^+-ATPase$ of the leaky microsomes made by the treatment of Triton X-100 were also inhibited by $La^{3+}$, suggesting that $La^{3+}$ directly inhibits both enzymes. Meanwhile, the inhibitory effect of $La^{3+}$ was decreased by increasing the concentration of ATP, The effect of ATP was also concentration-dependent and 7 mM ATP completely removed the inhibitory effect of $La^{3+}$. These results imply that $La^{3+}$ inhibits both plasma and vacuolar membrane $H^+-ATPases$ by decreasing the binding affinity of ATP and $La^{3+}$ can be used to control the activity or root $H^+-ATPases$.

• Animal cells and systems
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• v.8 no.4
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• pp.307-312
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• 2004

Fast kinetics of transient pH changes and difference spectrum formation have been investigated following mixing of ADP/ATP with partially purified plasma membrane PM-ATPase of the pathogenic yeast Candida albicans in the presence of five nutrients: glucose, glutamic acid, proline, lysine, and arginine and two analogs of glucose: 2-deoxy D-glucose and xylose. Average $H^+$- absorption to release ratio, indicative of population of ATPase undergoing complete hydrolytic cycle, was found to be 0.27 for control. This ratio varied between 0.25 (proline) to 0.36 (arginine) for all other compounds tested, except for glucose. In the presence of glucose, $H^+$- absorption to release ratio was exceptionally high (0.92). While no UV difference spectrum was observed with ADP, mixing of ATP with ATPase led to a large conformational change. Exposure to different nutrients restricted the magnitude of the conformational change; the analogs of glucose were found to be ineffective. This suppression was maximal in the case of glucose (80%); with other nutrients, the magnitude of suppression ranged from 40-50%. Rate of $H^+$- absorption, which is indicative of E~P complex dissociation, showed positive correlation with suppression of conformational change only in the case of glucose and no other nutrient/analog. Mode of interaction of glucose with plasma membrane $H^+$-ATPase thus appears to be strikingly distinct compared to that of other nutrients/analogs tested. The results obtained lead us to propose a model for explaining glucose stimulation of plasma membrane $H^+$-ATPase activity.

• Journal of Photoscience
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• v.9 no.2
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• pp.335-337
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• 2002

Blue light (BL) induces stomatal opening through activation of H$^{+}$ pump, which creates electrical gradient across the plasma membrane for $K^{+}$ uptake into guard cells. The pump is the plasma membrane H$^{+}$ -ATPase and is activated via phosphorylation of the C-terminus with concomitant binding of the 14-3-3 protein. The opening is initiated by the perception of BL through phototropin (phot), which are recently identified as BL receptors in stomatal guard cells. In this study, we provide the biochemical evidence for phots as BL receptors in stomatal guard cells. vfphot was phosphorylated reversibly by BL, and phosphorylation levels of vfphot increased earlier than those of the plasma membrane W-ATPase. BL-dependent phosphorylations of vfphot and H$^{+}$-ATPase showed similar fluence dependency. Staurosporin, an inhibitor of serine/threonine protein kinase, and diphenyleneiodonium chloride (DPI), an inhibitor of flavoprotein, inhibited BL-dependent phosphorylations of vfphot and H$^{+}$ -ATPase. These results indicate that vfphot acts as a BL-receptor mediating stomatal opening.l opening.

• Applied Biological Chemistry
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• v.42 no.4
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• pp.298-303
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• 1999

In order to characterize the effects of heavy metal ions on the microsomal ATPase activities, microsomes were prepared from the roots of tomato plant and the activity of microsomal ATPase was measured by an enzyme-coupled assay. $Hg^{2+}$ inhibited the activity of microsomal ATPase in a dose-dependent manner, while $Gd^{3+}$, $Fe^{3+}$, $La^{3+}$, $Zn^{2+}$, and $Pb^{2+}$ inhibited not only the ATPase activity but also the activities of enzymes used in the assay. However, $Cs^+$ and $Ba^{2+}$ showed no significant effect. $Hg^{2+}$ inhibited the activities of both plasma membrane and vacuolar membrane $H^+-ATPases$. In the dose-response to $Hg^{2+}$, the activities of both microsomal $H^+-ATPases$ were severely inhibited at the concentration of $Hg^{2+}$ above $10\;{\mu}M$ and were completely inhibited at 1 mM $Hg^{2+}$. Apparent Ki values of $Hg^{2+}$ on the inhibitions of plasma membrane and vacuolar membrane $H^+-ATPases$ were $80\;{\mu}M$ and $58\;{\mu}M$, respectively. The $Hg^{2+}$-induced inhibitions were reversible since the addition of dithiothreitol completely reversed the inhibitory effects of $Hg^{2+}$. These results suggest that the inhibitory effects of $Hg^{2+}$ on both plasma, membrane and vacuolar membrane $H^+-ATPases$ are nonselective and reversible.

• Journal of Plant Biotechnology
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• v.43 no.4
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• pp.405-410
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• 2016

Auxins are essential in plant growth and development. The auxin-stimulated elongation of plant cells has been explained by the "acid-growth theory", which was proposed forty years ago. According to this theory, the auxin activates plasma membrane $H^+-ATPase$ to induce proton extrusion into the apoplast, promoting cell expansion through the activation of cell wall-loosening proteins such as expansins. Even though accepted as the classical theory of auxin-induced cell growth for decades, the major signaling components comprising this model were unknown, until publication of recent reports. The major gap in the acid growth theory is the signaling mechanism by which auxin activates the plasma membrane $H^+-ATPase$. Recent genetic, molecular, and biochemical approaches reveal that several auxin-related molecules, such as TIR1/AFB AUX/IAA coreceptors and SMALL AUXIN UP RNA (SAUR), serve as important components of the acid-growth model, phosphorylating and subsequently activating the plasma membrane $H^+-ATPase$. These researches reestablish the four-decade-old theory by providing us the detailed signaling mechanism of auxininduced cell growth. In this review, we discuss the recent research progress in auxin-induced cell elongation, and a set of possible future works based on the reestablished acid-growth model.

• Journal of Photoscience
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• v.9 no.2
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• pp.86-89
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• 2002

Blue light activates proton pump, and creates electrical gradient across the plasma membrane and drives $K^{+}$ uptake in stomatal guard cells. In this presentation, we provide evidence for regulatory mechanisms of the pump and the identification of blue light receptor. The pump is shown to be the plasma membrane H$^{+}$- ATPase and is activated through phosphorylation of the C-terminus. Phosphorylation occurred and 14-3-3 protein bound to the phosphorylation site. The binding of 14-3-3 protein was required for the H$^{+}$-ATPase activation. We also found that phot1 phot2 double mutant does not respond to blue light but other mutants respond to blue light by stomatal opening. However, all these mutants are capable of stomatal opening in the presence of fusicoccin, an activator of the H$^{+}$-ATPase. These results suggest that both photl and phot2 act as blue light receptors in guard cells.d cells.

• Journal of Microbiology and Biotechnology
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• v.8 no.3
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• pp.197-202
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• 1998

Aliphatic alkenals having 6 to 13 carbons were evaluated for antifungal activity against Saccharomyces cerevisiae. The activity was gradually increased with chain length, e.g., (E)-2-decenal and (E)-2-undecenal exhibited maximum potency, while (E)-2-dodecenal and (E)-2-tridecenal were completely inactive. Alkenals showed increasing inhibitory activity with chain length, as in the case of antifungal activity, towards glucose-induced medium acidification by the plasma membrane $H^+$-ATPase of S. cerevisiae. The group including (E)-2-nonenal, (E)-2-decenal, and (E)-2-undecenal exhibited maximum potency, but the potency of (E)-2-dodecenal and (E)-2-tridecenal demonstrated a sudden drop with respect to the former group. (E)-2-Nonenal revealed dose-responsive inhibition to the medium acidification and inhibited over 90% at a concentration of 1.25 mM ($175.3{\mu}g$/ml). In contrast to (E)-2-undecenal whose inhibitory efficiency increased with incubation time, inhibition by (E)-2-dodecenal was reversed with time. Of the tested alkenals, (E)-2-heptenal and (E)-2-octenal most highly inhibited ATP hydrolytic activity by the plasma membrane $H^+$ ATPase, while (E)-2-heptenal at 10 mM ($1121.8{\mu}g$/ml) showed an inhibitory efficacy of 93.2%.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.212-216
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• 2005

Thapsigargin is a specific antagonist of SR/ER-type $Ca^{2+}-ATPase$ in animal tissue, and it was used to characterize the microsomal ATPases prepared from the roots of tomato. When $10\;{\mu}M$ thapsigargin was added, it inhibited the microsomal ATPase activity by 30%. The thapsigargin-induced inhibition was dose-dependent. Since the activity of $Ca^{2+}-ATPase$ is very low in the roots of tomato tissue, it is possible that thapsigargin inhibits the activities of major $H^+-ATPases$ located in plasma and vacuolar membranes. The inhibitory effect of thapsigargin was reduced when the vacuolar $H^+-ATPase$ activity was inhibited by ${NO_3}^-$. However, the effect of thapsigargin was not observed on the $H^+-ATPase$ activity located in the plasma membrane. These results suggest that thapsigargin inhibits the vacuolar $H^+-ATPase$ activity in the roots of tomato.