+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Evidence for Two Catalytic Sites in the Functional Unit of H+-ATPase from Higher Plants

, : Evidence for Two Catalytic Sites in the Functional Unit of H+-ATPase from Higher Plants. Plant Physiology 108(2): 813-819

We investigated the nature of the complex ATP activation kinetics of plant H+-ATPases. To this aim we analyzed that activation in three isolated isoforms (AHA1, AHA2, and AHA3) of H+-ATPase from Arabidopsis thaliana. The isoforms were obtained by heterologous expression in endoplasmic reticulum of yeast. ATP stimulation was always with low affinity (K0.5) between 500 and 1800 micromolar). In addition, the curves were not Michaelian and displayed positive cooperativity. Detailed studies with AHA2 showed that (a) enzyme solubilized with lysophosphatidylcholine exhibited Michaelian behavior even in the presence of soybean lecithin liposomes free of enzyme, (b) solubilized enzyme incorporated into the same liposomes displayed two-site kindles with negative cooperativity, and (c) enzyme partially digested with trypsin lost the C-terminal portion of the molecule. Under this condition the ATP activation kinetics was Michaelian or had a slight negative cooperativity and the K0.5ATP was reduced 3-fold. These data suggest that the functional unit of the H+-ATPase has two catalytic ATP sites with variable cooperativity and kindles competence of the E(ATP) and E(ATP)2 complexes. Such variability is likely modulated by the association of the enzyme with membrane structures and by a regulatory domain in the C terminus of the enzyme molecule.


PMID: 12228512

DOI: 10.2307/4276608

Other references

Kephart, K.D.; Buxton, D.R., 1989: Adaptation and forage quality of grasses grown under shade. The C3 grasses Panicum clandestinum, Phalaris arundinacea and Festuca arundinacea and the C4 grasses Panicum virgatum and Andropogon gerardii were artificially shaded to give 37, 70 and 100% of full light intensity. Morphological adaptations to re...

Gonzales C.Angel, 1983: Description of the phosphate deposits of Bolivia. Geociencias (Cochabamba): Pages 3. 1983.

McCarthy, M., 2015: Early signs show that 2014-15 flu season may be severe, CDC warns. Bmj 349: G7530-G7530

Sinha, B.K.; Singh, N.T., 1977: Effect of moisture content on diffusion coefficient of chloride ions in Tulewal loamy sand. As soil moisture content decreased from 28.8 to 10.5%, the diffusion coefficient of chloride ions in the soil, measured by the use of 36Cl-, decreased from 5.48 X 10-6 to 0.486 X 10-6 cm2 sec-1. The tortuosity factor also decreased, from 0.301 to...

Treacy, W., 1993: Alternative dispute resolution of medical malpractice cases in Wisconsin. Wisconsin Medical Journal 92(3): 144-147

Bonavia L.; Casellato A.; Blini M.; Draghi E.; Bertoni G., 1982: Natural evolution of branch retinal vein occlusion. Haemostasis 12(1-2): 217

Vessey, J.A., 2007: Development of the Massachusetts School Nurse Research Network (MASNRN): A Practice-Based Research Network to improve the quality of school nursing practice. When school nurses embrace evidence-based practice (EBP), higher-quality care is provided to students, their families, and the larger community. Despite this, school nursing has been slow to embrace EBP. Practice-Based Research Networks (PBRNs), w...

Schmidt, K.G.; Klingmueller, V.; Boehm, A.G.; Osborne, N.N.; Pillunat, L.E., 2003: Perioptic short posterior ciliary artery and central retinal artery hemodynamics in primary open angle glaucoma patients on brimonidine. Purpose: Peripapillary hemodynamics is increasingly being discussed in the prognosis of primary open angle glaucoma (PAOG). Current antiglaucomatous drugs - in addition to reducing intraocular pressure (IOP) - should not impair perfusion to the op...

Honnor, A., 2008: The management of chronic oedema in palliative care. Chronic oedema is a broad term used to describe a range of conditions which may cause oedema in the limbs, trunk, head, neck and genitals. Lymphoedema is one type of chronic oedema. The problems associated with chronic oedema can be devastating an...

Hussein, K.; Peter, C.; Sedlacek, L.; Kaisenberg, C.von.; Kreipe, H.H., 2016: Necrotizing funisitis : Histopathological indicator of occult congenital syphilis. NlmCategory="UNASSIGNED">Congenital syphilis is a rare disease in central Europe. Placental changes may be non-specific but a typical finding is necrotizing funisitis of the umbilical cord. In a case report we describe how the histopa...