Characterization of the effects of divalent cations on the coupled activities of the H sup + -ATPase in tonoplast vesicles

Journal Article · Tue Aug 01 04:00:00 EDT 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.90.4.1636· OSTI ID:6643671

Tu, Shui; Nungesser, E; Brauer, D ^[1]

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1. Department of Agriculture, Philadelphia, PA (USA)

The substrate requirement of the H{sup +}-ATPase in purified corn root tonoplast vesicles was investigated. The coupled activities, ATP hydrolysis and proton pumping, were simultaneously supported only by Mg{sup 2+} or Mn{sup 2+}. The presence of Ca{sup 2+} or Ba{sup 2+} did not significantly affect the coupled activities. The addition of Cd{sup 2+}, Co{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} inhibited both the hydrolysis of Mg-ATP and the proton transport. However, the inhibition of proton pumping was more pronounced. Based on equilibrium analysis, both ATP-complexed and free forms of these cations were inhibitory. Inhibition of the hydrolysis of Mg-ATP could be correlated to the concentrations of the ATP-complex of Zn. On the other hand, the free Cu{sup 2+} and Co{sup 2+} were effective in inhibiting hydrolysis. For proton pumping, the ATP complexes of Co{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} were effective inhibitors. However, this inhibition could be further modulated by free Co{sup 2+}, Cu{sup 2+}, and Zn{sup 2+}. While the equilibrium concentrations of Cd-ATP and free Cd{sup 2+} were not estimated, the total concentration of this cation needed to inhibit the coupled activities of the H{sup +}-ATPase was found to be in the range of 10 to 100 micromolars. The presence of free divalent cations also affected the structure of the lipid phase in tonoplast membrane as demonstrated by the changes of emission intensity and polarization of incorporated 1,6-diphenyl-1,3,5-hexatriene.

• OSTI ID: 6643671
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 90:4; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID ANHYDRASES
ALKALINE EARTH METALS
ATP-ASE
BARIUM
BARYONS
BIOLOGICAL EFFECTS
CADMIUM
CALCIUM
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CEREALS
CHARGED PARTICLES
CHEMICAL COMPOSITION
COBALT
COPPER
ELEMENTARY PARTICLES
ELEMENTS
ENZYME ACTIVITY
ENZYMES
FERMIONS
GRASS
HADRONS
HYDROLASES
INHIBITION
IONS
LILIOPSIDA
MAGNESIUM
MAGNOLIOPHYTA
MAIZE
MANGANESE
MEMBRANE TRANSPORT
MEMBRANES
METALS
NUCLEONS
PHOSPHOHYDROLASES
PLANTS
PROTONS
ROOTS
TRANSITION ELEMENTS
ZINC