Active vanadate-sensitive H+ translocation in corn roots membrane vesicles and proteoliposomes |
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| Institution: | 1. Laboratoire de Physiopathologie Végétale, I.N.R.A., B.V. 1540, 21034 Dijon Cedex France;2. Laboratoire des Herbicides, I.N.R.A., B.V. 1540, 21034 Dijon Cedex France;1. The University of Queensland, Institute for Social Science Research, Indooroopilly, Qld 4068, Australia;2. The University of Queensland, School of Public Health, Herston, Qld 4006, Australia;3. Department of Epidemiology and Biostatistics, Institute of Public Health, University of Gondar, Ethiopia;1. Department of Medical Oncology, Inselspital, Bern University Hospital, University of Bern, Bern 3010 Switzerland;2. Department for BioMedical Research, University of Bern, Bern 3008, Switzerland;3. Institute of Genetics and Biophysics “Adriano Buzzati-Traverso” CNR, Naples 80131, Italy;4. Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern 3012, Switzerland;5. Department of Microbiology, Immunology, and Cell Biology, Morgantown, WV, USA;6. Department of Surgery, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong;7. Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong;8. Key Laboratory of Biochip Technology, Biotech and Health Centre, Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China;9. Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology (BIST), Barcelona, Catalonia 08003, Spain;10. GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, Granada 18016, Spain;11. Instituto de Investigación Biosanitaria, Granada 18014, Spain;12. Department of Biochemistry and Molecular Biology I, University of Granada, Granada 18071, Spain;13. Penn State Cancer Institute, Hershey, PA 17033, USA;14. School of Biology and Environmental Science, University College Dublin, Dublin D04 V1W8, Ireland;15. Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Dublin D04 V1W8, Ireland;1. Electron Science Research Institute, Edith Cowan University, Joondalup, WA 6027, Australia;2. School of Science, Edith Cowan University, Joondalup, WA 6027, Australia;1. Wesley Hospital, Brisbane, Australia;2. Wesley Medical Imaging, Brisbane, Australia;3. Heart Care Partners, Brisbane, Australia;4. ICON Cancer Care, Brisbane, Australia;5. University of Queensland, Brisbane, Australia |
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| Abstract: | A member fraction from corn roots which contains a vanadate-sensitive ATPase activity has been prepared. The specific activity at 38°C is between 3 and mol 12 μmol · min?1 · mg?1, depending on the age of roots. Addition of ATP promotes a very rapid quenching of the fluorescence of 9-amino-6-chloro-3-methoxy-acridin (ACMA). Proton pumping exhibits a delayed sensitivity to vanadate but is strongly and instantaneously inhibited by the new inhibitor SW 26. Both proton pumping, measured by the initial quenching rate, and ATP hydrolysis show maximum activities at ATP concentrations in the millimolar range, but the apparent Km-value for hydrolysis is higher than that observed for proton pumping. This is interpreted as being due to the presence of two populations of ATPases, one of them hydrolyzing ATP without creating a pH-gradient. The vanadate-sensitive ATP hydrolysis and H+-pumping activity may be solubilized with lysolecithin and reconstituted into liposomes either by a freeze-thawing-sonication or an octylglucoside dilution procedure. Both methods yield proteoliposomes exhibiting very effecient proton pumping, which is more sensitive to vanadate (I50 = 2 μM) or to SW 26 (I50 = 0.5 μM) than that of the original membrane fractions. |
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