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Vanadate

About: Vanadate is a research topic. Over the lifetime, 4497 publications have been published within this topic receiving 120109 citations. The topic is also known as: vanadate.


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Journal ArticleDOI
TL;DR: The results indicate many similarities with respect to vanadate inhibition between the plant plasma membrane ATPase and other major iontranslocating ATPases from fungal and animal cells.
Abstract: The effect of vanadate on the plant plasma membrane ATPase were investigated in plasma membrane fractions derived from corn roots (Zea mays L) and red beets (Beta vulgaris L) The Ki for vanadate inhibition of the plasma membrane ATPase from corn roots and red beets was between 6 and 15 micromolar vanadate In both membrane fractions, 80% to 90% of the total ATPase was inhibited at vanadate concentrations below 100 micromolar Vanadate inhibition was optimal at pH 65, enhanced by the presence of K+, and was partially reversed by 1 millimolar EDTA The Mg:ATP kinetics for the plasma membrane ATPase were hyperbolic in both the absence and presence of vanadate Vanadate decreased both the Km and Vmax of the red beet plasma membrane ATPase, indicating that vanadate inhibits the ATPase uncompetitively These results indicate many similarities with respect to vanadate inhibition between the plant plasma membrane ATPase and other major iontranslocating ATPases from fungal and animal cells The high sensitivity to vanadate reported here, however, differs from other reports of vanadate inhibition of the plant plasma membrane ATPase from corn, beets, and in some instances oats

108 citations

Journal ArticleDOI
TL;DR: The results suggest that the intrinsic ATPase activity of purified MalK can be clearly distinguished from other ATP-hydrolyzing enzymes, e.g. ion-translocating ATPases.

107 citations

Journal ArticleDOI
TL;DR: It is argued that several Ca2+- and pH-related processes are pivotal for tip growth in root hairs: with respect to Ca2+, these are an inwardly directed Ca1+-current, localized elevated cytosolic [Ca2+] in the tip, and constant Ca2-circulation.
Abstract: SUMMARY In Sinapis root hair cells, tip growth has been measured and studied with different electrophysiological techniques. Applying ion-selective microelectrodes, we measured 452–776 nM free [Ca2+] in the tip, which is about three times the concentration found in the base. The cytosolic pH of 7.1–7.3 in the tip is statistically not different from values measured in the base. The cells react to changes in external [Ca2+] between 0.01 and 10 mM with transient changes in growth intensity and cytosolic [Ca2+]: increased external [Ca2+] elevates cytosolic [Ca2+] followed by a growth burst. Whereas external [Ca2+] lower than 1 μM is inhibitory to steady state tip growth, concentrations up to 30 mM are not. Vibrating probe analysis reveals inwardly directed net Ca2+-currents in the tip only. The calcium channel antagonists nifedipine and La3+ decrease cytosolic free [Ca2+], inhibit the inwardly directed Ca2+-current and tip growth. Dibromo-BAPTA, injected into the cells, also decreases cytosolic [Ca2+] and inhibits growth, but only marginally depolarizes the cells. Abrupt changes in external pH between 5 and 9 affect cytosolic pH and transiently inhibit tip growth, regardless of the direction of the pH-shift. Acetic acid and NH4Cl both inhibit tip growth only, when the cytosolic pH is shifted from its steady state value. Tip growth is inhibited in the presence of the ATPase inhibitors DCCD, vanadate and erythrosin B. We argue that several Ca2+- and pH-related processes are pivotal for tip growth in root hairs: with respect to Ca2+, these are an inwardly directed Ca2+-current, localized elevated cytosolic [Ca2+] in the tip, and constant Ca2+-circulation. For pH, an active H+-pump and a tightly regulated cytosolic pH at the tip appear important, however not an internal pH-gradient.

106 citations

Journal ArticleDOI
TL;DR: Experiments in which the transmembrane K+ gradient has been abolished or decreased with ionophores, or by increasing the K+ concentration in the medium, suggest that theK+ gradient may play a role in the influx of Ca2+.

106 citations

Journal ArticleDOI
TL;DR: The rate of NADH oxidation with oxygen as the acceptor is very low in mouse liver plasma membrane and erythrocyte membrane, but when vanadate is added, this rate is stimulated 10- to 20-fold, indicating that oxygen is the electron acceptor and the reaction is mediated by superoxide.

106 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023109
2022211
202178
202075
201996
201899