Reversibility of H+-ATPase and H+-pyrophosphatase in tonoplast vesicles from maize coleoptiles and seeds

Tonoplast-enriched vesicles isolated from maize (Zea mays L.) coleoptiles and seeds synthesize ATP from ADP and inorganic phosphate (Pi) and inorganic pyrophosphate from Pi. The synthesis is consistent with reversal of the catalytic cycle of the H(+)-ATPase and H(+)-pyrophosphatase (PPase) vacuolar...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1998-04, Vol.116 (4), p.1487-1495
Main Authors: Facanha, A.R. (Universidade Federal do Rio de Janeiro, Brazil.), Meis, L. de
Format: Article
Language:English
Subjects:
Adenosine triphosphatases
ADENOSINETRIPHOSPHATASE
ADP
Agronomy. Soil science and plant productions
ANIONS
ATP
ATP PYROPHOSPHATASE
ATPASE
Bioenergetics
Biological and medical sciences
BIOSYNTHESIS
CELL DIFFERENTIATION
CELL MEMBRANES
CHEMICAL COMPOSITION
COLEOPTILES
Corn
DEVELOPMENTAL STAGES
Economic plant physiology
Enzymes
ENZYMIC ACTIVITY
Fundamental and applied biological sciences. Psychology
HYDROLASES
Hydrolysis
ION EXCHANGE
LOCALIZATION
MEASUREMENT
Metabolism
Molecules
Nutrition. Photosynthesis. Respiration. Metabolism
PHOSPHATE
PHOSPHATES
Plant physiology and development
PRECURSORS
PROTEINS
Proton pump inhibitors
Protons
PYROPHOSPHATES
RADIOACTIVE TRACERS
RADIOISOTOPES
SEEDS
Tonoplast
Yeasts
ZEA MAYS
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Summary:Tonoplast-enriched vesicles isolated from maize (Zea mays L.) coleoptiles and seeds synthesize ATP from ADP and inorganic phosphate (Pi) and inorganic pyrophosphate from Pi. The synthesis is consistent with reversal of the catalytic cycle of the H(+)-ATPase and H(+)-pyrophosphatase (PPase) vacuolar membrane-bound enzymes. This was monitored by measuring the exchange reaction that leads to 32Pi incorporation into ATP or inorganic pyrophosphate. The reversal reactions of these enzymes were dependent on the proton gradient formed across the vesicle membrane and were susceptible to the uncoupler carbonyl cyanide p(trifluoromethoxy)-phenylhydrazone and the detergent Triton X-100. Comparison of the two H(+) pumps showed that the H(+)-ATPase was more active than H(+)-PPase in coleoptile tonoplast vesicles, whereas in seed vesicles H(+)-PPase activity was clearly dominant. These findings may reflect the physiological significance of these enzymes in different tissues at different stages of development and/or differentiation
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.116.4.1487