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Topic: Proton pumps


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In the News (Sat 20 Apr 19)

  
  New proton pump inhibitor licensed for on demand use   (Site not responding. Last check: 2007-10-06)
It is the first proton pump inhibitor to be licensed for "on demand" use.
Esomeprazole is the first proton pump inhibitor to be developed as a single optical isomer.
He said that compared with omeprazole, there was a "60 per cent extra blocking of proton pumps", resulting in more sustained acid control for a longer period of time.
www.pharmj.com /Editorial/20000916/clinical/newprotonpumpinhibitor.html   (450 words)

  
 Positive Electricity Zaps Through Water Chains
The protons pumped uphill (to a higher energy state), using an external energy source, such as the oxidation of foodstuff, or absorption of sunlight, is returned downhill via another enzyme, ATP synthase embedded in the same membrane, which uses the energy to make ATP, the universal energy intermediate that powers all living activities.
The protons are supposed to exist in bulk solution on either side of the membrane, and it is the difference in concentration between the two compartments separated by the membrane that drives the synthesis of ATP.
Structural studies carried out on these proton pumps within the past ten years show that they form a channel through the cell membrane that is threaded by a chain of hydrogen-bonding water molecules from one side of the membrane to the other [2].
www.i-sis.org.uk /PEZTWC.php   (1434 words)

  
  Lycos Retriever: Search results for proton
Replacing the proton with its antimatter counterpart, the antiproton, and the electron with its antimatter counterpart, the positron, would change hydrogen to antihydrogen.
Either by the movement of electrons across the surface of the object (as is the case in conductors) or through the distortion of electron clouds (as is the case in insulators), the centers of positive and negative charges become separated from each other.
While there are the same number of protons and electrons within the object, these protons and electrons are not distributed in the same proportion across the object's surface.
www.lycos.com /info/proton--pumps.html   (733 words)

  
  Molecular architecture and action of a proton pump
Proton pumps in the membrane surrounding plant and yeast cells maintain the intracellular pH.
The yeast proton pump is a member of the family of the so-called P-type ATPases.
The Frankfurt group discovered that the last 38 of the proton pump's 920 amino acids form a separate entity which appears to inhibit the molecular motions and the release of energy that drives the pumping process.
www.eurekalert.org /pub_releases/2002-08/m-maa080902.php   (500 words)

  
 [No title]
-Transporting ATPases (proton pumps) are the main ion pumps in the plasma membrane and play a central role [1] in the physiology and bioenergetics of plant cells.
They are the primary active transporters of the plasma membrane and are responsible for generating the membrane potential that drives translocation of cations, amino-acids, sugars, and hormones, whilst also contributing to the maintenance of intracellular and extracellular pH and cell turgor [2].
Proton pumps are members of the P-type (or E1-E2-type) cation-transporting ATPase superfamily, which has evolved from a common ancestral gene [3].
www.ebi.ac.uk /interpro/IEntry?ac=IPR000695   (690 words)

  
 The vacuolar proton pump of Dictyostelium discoideum: molecular cloning and analysis of the 100 kDa subunit -- Liu and ...
The vacuolar proton pump of Dictyostelium discoideum: molecular cloning and analysis of the 100 kDa subunit -- Liu and Clarke 109 (5): 1041 -- Journal of Cell Science
The vacuolar proton pump of Dictyostelium discoideum: molecular cloning and analysis of the 100 kDa subunit
The vacuolar proton pump is a highly-conserved multimeric enzyme that
jcs.biologists.org /cgi/content/abstract/109/5/1041   (467 words)

  
 Cuiabstract/html
Proton pumps and molecular motors are fascinating “vectorial machines” in biology that convert energy between different forms with high efficiency.
Recent advances in the experimental characterizations of these systems have provided excellent background and impetus for carrying out detailed theoretical and computational analyses, such that the underlying mechanism and governing physicochemical principles for these unique biological systems can be understood in energetic and structural terms.
In the case of carbonic anhydrase, which has been regarded as a prototypical enzyme involving long-range proton transfers, the theoretical study raises the interesting possibility that the proton transfers occur through a mechanism different from the traditional Grotthuss paradigm.
jfi.uchicago.edu /events/abstracts/Cuiabstract.html   (144 words)

  
 FRISC > Faculty Profiles > Xiao-Song Xie, Ph.D.
Isolation and reconstitution of a vacuolar-type proton pump of osteoclast membranes.
Proton translocation catalyzed by the electrogenic ATPase in the plasma membrane of Neurospora.
The role of cytochrome a in the proton pump of cytochrome-c oxidase.
invention.swmed.edu /frisc/faculty/xie/profile.shtml   (3992 words)

  
 Directional Proton Transport   (Site not responding. Last check: 2007-10-06)
This coupling of a conformational shift with a hydrogen-bonded chain of proton acceptors to generate irreversibly a transmembrane proton gradient is thought to be used by bacteriorhodopsin [33].
Proton transfer would proceed from histidine to a secondary acceptor and the back reaction would be prevented by tautomerization of the histidine ring.
Modern proton pumps are thought to utilize a complex chain of hydrogen-bonded residues as well as internal isomerizations for irreversible proton transport across cell membranes.
exobiology.nasa.gov /ssx/biomod/1996_pac_symp_biocomp/node5.html   (1274 words)

  
 Digital medical - Tech research focuses on beating drug-resistant cancer 12/30/99
The new gene was dubbed a proton pump, a mechanism inside normal cells that ejects acid and maintains the cell's pH balance.
Using mouse cells, Martinez-Zaguilan and his team found that cancerous tumors have proton pumps on their surfaces, unlike normal cells where the proton pumps are inside the cell wall.
He thinks that the expression of proton pumps at the surface of a cell may be a predictor that the cell is an aggressive, invasive tumor, what oncologists call a metastatic tumor.
www.lubbockonline.com /stories/123099/med_123099080.shtml   (1527 words)

  
 Infant Reflux and GERD Treatments
Proton Pump Inhibitors (PPI's) act by blocking the proton pump (hydrogen-potassium adenosine triphosphatase enzyme system-the K+/H+-ATPase) of the parietal cell.
Proton pump inhibitors are typically tried after histamine blockers have failed, as the cost can be more than double that of the histamine blockers.
It's not uncommon for proton pump inhibitors and prokinetics to be prescribed simultaneously for stubborn cases of reflux.
www.infantrefluxdisease.com /treatments.htm   (1920 words)

  
 Computer-aided design of a proton pump   (Site not responding. Last check: 2007-10-06)
There are two basic components to a simple light-driven proton pump: a source of photo-generated protons and a ``gate-keeper'' which prevents these protons from re-attaching themselves to their source.
Back transfer of the proton to the first acceptor, and thence to the proton source, is impeded by the free energy required to move the proton uphill towards the proton source and by the disruption of the transient water bridge.
As a prototypical water-bridged proton transfer system, we are studying the transfer of a proton across a water bridge from a formic acid to a formate anion.
exobiology.nasa.gov /ssx/biomod/psb97/psb97.html   (513 words)

  
 MOCB Program Faculty: Dr. Heven Sze
Major goals are (1) to identify and characterize Ca pumps after functional expression of plant genes in yeast mutants; (2) understand how expression and activity of transporters are regulated, and (3) understand the in vivo functions in plants.
Proton pumps occupy a prominent position among transporters in plants and yeast.
A major proton pump (vacuolar H+-ATPase) acidifies the vacuole and endomembrane compartments, and provides the driving force for transport of many ions and metabolites across the vacuolar membrane.
www.life.umd.edu /grad/mocb/faculty/sze.html   (379 words)

  
 Oxidative Phosphorylation--Respiratory chain and Chemiosmotic hypothesis
Pumping of protons by the respiratory chain complexes is the primary energy conserving event of oxidative phosphorylation
The protons are pumped from the matrix to the cytosolic side of the inner mitochondrial membrane.
As the electrons are transfered, protons are pumped into the intermembrane space of the mitochondria resulting in the formation of a proton gradient.
www.dentistry.leeds.ac.uk /biochem/uttb/OXPHOS2.HTM   (1629 words)

  
 Electron transport chain Summary
During this process, four protons are translocated across the inner mitochondrial membrane, from the matrix to the intermembrane space.
The result is the disappearance of a proton from the cytoplasm and the appearance of a proton in the periplasm.
Proton pumps are the heart of the electron transport process.
www.bookrags.com /Electron_transport_chain   (3686 words)

  
 Ion pumps as targets for therapeutic intervention: Old and new paradigms
These latter ion pump classes are multi-subunit complexes of more than 9 different subunits that are largely proton pumps involved in either ATP synthesis or intracellular acidification (Boyer, 1997; Forgac, 1992).
The proton pump inhibitors omeprazole (losec), lansoprazole (prevacid), and pantoprazole belong to the chemical family of substituted benzimidazoles (Fig.
Unlike classical enzyme inhibitors, which derive their specificity from lock and key-type structural mechanisms, the highly selective nature of covalent proton pump antagonists is derived from their accumulation in the acid environment of the secretory canaliculus, which activates pro-drug in close proximity to its target.
www.ejbiotechnology.info /content/vol1/issue2/full/2/index.html   (6223 words)

  
 Proton Pump Inhibitors: An Update American Family Physician - Find Articles   (Site not responding. Last check: 2007-10-06)
Proton pump inhibitors have minimal side effects and few significant drug interactions, and they are generally considered safe for long-term treatment.
The proton pump inhibitors omeprazole, lansoprazole, rabeprazole, and the recently approved esomeprazole appear to have similar efficacy.
Proton pump inhibitors (PPIs) are one of the most commonly prescribed classes of medications in the primary care setting and are considered a major advance in the treatment of acid-peptic diseases.
www.findarticles.com /p/articles/mi_m3225/is_2_66/ai_89274369   (658 words)

  
 Lecture 12: Proton conduction, proton channels, proton wells
Water is a good conductor of protons, because of the H-bonded networks between water molecules (see gramicidin tutorial for a nice view of water structure from a molecular dynamics simulation), that give water its liquid properties in the physiological range.
In other protolytic reactions involving proton pumping, the sites at which protons are bound or released are often buried in the protein; the center at which vectorial work is done on the proton is relatively immobile, and this requires access pathways through the protein.
Proton channels linked to proton "activating" devices are well characterized in two systems in which the prosthetic groups involved have a restricted mobility.
www.life.uiuc.edu /crofts/bioph354/lect12.html   (962 words)

  
 MARCI-Kids Midwest Acid Reflux Children's Institute
Proton pumps are tiny pumps located in the parietal cell that produce stomach acid (Figure 6).
Active pumps (those that are currently pumping out stomach acid) are found on the surface of the cell, in the canaliculus.
Inactive pumps are on hold inside the cell, in the walls of tubulovesicles (bubble-like holding areas) waiting to be called on to secrete acid.
www.marci-kids.com /acidprodn.html   (752 words)

  
 Scientists Discover Genetic Key To Growing Hardier, More Productive Plants
Their work is the first to successfully test in cells a 30-year-old hypothesis that explains the movement of a primary growth and development hormone through plants and is expected to prompt biology textbooks to be rewritten.
Over-expressing the single gene that encodes this particular proton pump significantly enhances the transportation of the primary plant growth hormone, auxin, and results in plants with stronger, more extensive root systems and as much as 60 percent more foliage, the researchers report in the Oct. 7 issue of the prestigious journal Science.
Gaxiola specializes in manipulating plant proton pumps for crop improvement and relied on Murphy and Purdue colleague Wendy Peer, for expertise in auxin transport in plants, and Gilroy for expertise in plant cell biology with an emphasis on roots.
www.spacedaily.com /news/life-05zzzzzzi.html   (1099 words)

  
 The Mechanochemistry of V-ATPase Proton Pumps -- Grabe et al. 78 (6): 2798 -- Biophysical Journal
) responsible for the translocation of protons, and a soluble
of the V-ATPase proton pumps and summarizes the subunit notation
The proton pumping rate is plotted as a function of membrane potential and pH gradient.
www.biophysj.org /cgi/content/full/78/6/2798   (6461 words)

  
 Fungal plasma membrane proton pumps as promising new antifungal targets.
The fungal plasma-membrane proton pump is a high-abundance essential enzyme with a number of well-understood molecular properties that should facilitate the development of new antifungals.
The proton pump is important for intracellular pH regulation and the maintenance of electrochemical proton gradients needed for nutrient uptake.
New antifungal drugs of this type should be relevant to the control of fungal pathogens of medical and agricultural importance and may be applicable to the control of intracellular parasites that also depend on closely related proton pumps for survival.
www.aegis.com /aidsline/1995/apr/M9541045.html   (589 words)

  
 Recombinant SFD Isoforms Activate Vacuolar Proton Pumps -- Zhou et al. 274 (22): 15913 -- Journal of Biological ...
of the vacuolar proton pump of clathrin-coated vesicles of bovine
Proton pump was harvested from the bottom one-third of the gradient
Proton pump purified from bovine chromaffin granule membranes was treated with 1% Zwittergent 3-16, followed by glycerol gradient centrifugation as described under "Experimental Procedures." Panel A (SDS-PAGE) shows that SFD-depleted pump (with dominant polypeptides of 70-, 58-, and 33-kDa) migrates near the bottom (lanes 3 and 4) of the glycerol gradient.
www.jbc.org /cgi/content/full/274/22/15913   (4411 words)

  
 Vacuolar and Plasma Membrane Proton-Adenosinetriphosphatases -- Nelson and Harvey 79 (2): 361 -- Physiological Reviews
membranes by an ATP-dependent proton uptake and that the proton
proton pump operates in the vacuoles of fungi and plants (23,
pump that was shown to be V-ATPase (140, 173, 176).
physrev.physiology.org /cgi/content/full/79/2/361   (9591 words)

  
 Heartburn Medicines - Choosing ZEGERID for Heartburn Treatment
With each dose, the the heartburn medicine in a proton pump inhibitor gets into the bloodstream and attaches to some of these pumps, blocking the release of acid.
Once a pump is blocked by a proton pump inhibitor, it is "turned off" and can no longer release acid, providing effective heartburn treatment from your heartburn medicine.
ZEGERID is a proton pump inhibitor and is a heartburn medicine used for acid reflux treatment.
www.zegerid.com /Why_ZEGERID_Omeprazole/index.htm   (511 words)

  
 Mitochondrial Substructure
At each site is a hydrogen (or proton) pump which transfers hydrogen from one side of the membrane to the other.
This chemiosmotic pumping creates an electrochemical proton gradient across the membrane which is used to drive the "energy producing machine"...the ATP synthase.
The pumps then transport the hydrogens ions to the space between the two membranes where they accumulate in a high enough concentration to fuel the ATP pumps.
www.cytochemistry.net /Cell-biology/mitochondria_1.htm   (1840 words)

  
 Ion pumps as targets for therapeutic intervention   (Site not responding. Last check: 2007-10-06)
Representative examples include the sodium pump of cardiac cells, which is blocked by the action of cardiac glycosides like digoxin (lanoxin) used to treat heart disease, and the proton pump of stomach, which is selectively blocked by the action of omeprazole (prilosec), an acid blocker used to treat gastric ulcers and other gastrointestinal disorders.
The P-type ion pumps comprise a large family of proteins in animal, plant, bacterial and fungal cells that are responsible for the active movement of ions in cells.
The proton pump is one of the few antifungal targets that have been demonstrated to be essential by gene disruption techniques, and it has been linked to the ability of fungi to cause disease.
www.scielo.cl /fbpe/img/ejb/v1n2/2/bip   (2531 words)

  
 Proton Pump Inhibitors Linked to Fracture Risk - CME Teaching Brief® - MedPage Today
Explain to interested patients that while long-term use of proton pump inhibitors for acid reflux suppression was associated in this study with higher risk of hip fracture, short-term use is unlikely to have an effect.
Previous studies have suggested that proton pump inhibitors may interfere with calcium absorption by inducing hypochlorhydria but have an opposite effect in reducing bone resorption by inhibiting osteoclastic vacuolar proton pumps.
The researchers found that the adjusted odds ratio for hip fracture with more than a year of proton pump inhibitor therapy was 1.44 (95% confidence interval 1.30 to 1.59).
www.medpagetoday.com /Endocrinology/GeneralEndocrinology/tb/4765   (924 words)

  
 Reflux1.com - PPIs
These proton "gradients" are actually pumped across membranes by special protein formations aptly known as "proton pumps." Unfortunately for patients suffering from Gastroesophageal Reflux Disease (GERD), several proton pumps around the stomach function as stimulants to the production of gastric acid.
Prescription medications known as proton pump inhibitors (PPIs) are widely prescribed to obstruct the action of these pumps, affording a great measure of relief from the painful symptoms of GERD.
PPIs inhibit the proton flow by binding to the enzyme on the surface of the cells of the stomach wall.
www.reflux1.com /care/refluxprocedure20.cfm/4   (429 words)

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