THE HYDROLYSIS OF ADENOSINE TRIPHOSPHATE BY BRAIN SUSPENSIONS

1954 ◽  
Vol 32 (5) ◽  
pp. 471-483 ◽  
Author(s):  
Hanna M. Pappius ◽  
K. A. C. Elliott
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphate ◽  
Atp Hydrolysis ◽  
Standard Procedure ◽  
High Energy ◽  
Unit Weight ◽  
Bicarbonate Buffer ◽  
Low Magnesium ◽  
Optimum Ph ◽  
Hydrolysis Of

Adenosine triphosphate (ATP) hydrolysis by unfractionated brain suspensions has been measured manometrically and chemically in bicarbonate buffer. Both magnesium and, less strongly, calcium accelerate ATP hydrolysis by brain suspensions. The effectiveness of low magnesium or calcium concentrations is decreased by relatively high ATP concentrations. The optimum pH for phosphate liberation is about 8. The ratio of carbon dioxide evolved to inorganic phosphate liberated depends on the pH. Evidence is given that the suspensions contain a Mg-activated ATPase which is strongly inhibited by calcium, a Ca-activated ATPase, and a Mg-activated PPase which is strongly inhibited by calcium but is different from the Mg-ATPase. These enzymes were not obtained in "latent" form nor activated by glutathione. Ethylenediamine tetraacetate can inhibit Ca-ATPase completely but is less effective on the Mg-ATPase and can release the latter from calcium inhibition. Other inhibitors have been tested.The ATPase activity of cerebral cortex of mouse, rat, cat, beef, and man has been measured by a standard procedure. The activity per unit weight decreases with increasing size of the animal parallel to the decrease in the oxygen uptake rate. Calculations show that the ATPase activity is high enough to release all high energy phosphate which could be produced by esterification coupled with respiration.

THE HYDROLYSIS OF ADENOSINE TRIPHOSPHATE BY BRAIN SUSPENSIONS

1954 ◽  
Vol 32 (1) ◽  
pp. 471-483 ◽  
Author(s):  
Hanna M. Pappius ◽  
K. A. C. Elliott
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphate ◽  
Atp Hydrolysis ◽  
Standard Procedure ◽  
High Energy ◽  
Unit Weight ◽  
Bicarbonate Buffer ◽  
Low Magnesium ◽  
Optimum Ph ◽  
Hydrolysis Of

Adenosine triphosphate (ATP) hydrolysis by unfractionated brain suspensions has been measured manometrically and chemically in bicarbonate buffer. Both magnesium and, less strongly, calcium accelerate ATP hydrolysis by brain suspensions. The effectiveness of low magnesium or calcium concentrations is decreased by relatively high ATP concentrations. The optimum pH for phosphate liberation is about 8. The ratio of carbon dioxide evolved to inorganic phosphate liberated depends on the pH. Evidence is given that the suspensions contain a Mg-activated ATPase which is strongly inhibited by calcium, a Ca-activated ATPase, and a Mg-activated PPase which is strongly inhibited by calcium but is different from the Mg-ATPase. These enzymes were not obtained in "latent" form nor activated by glutathione. Ethylenediamine tetraacetate can inhibit Ca-ATPase completely but is less effective on the Mg-ATPase and can release the latter from calcium inhibition. Other inhibitors have been tested.The ATPase activity of cerebral cortex of mouse, rat, cat, beef, and man has been measured by a standard procedure. The activity per unit weight decreases with increasing size of the animal parallel to the decrease in the oxygen uptake rate. Calculations show that the ATPase activity is high enough to release all high energy phosphate which could be produced by esterification coupled with respiration.

scholarly journals Dissociation of clathrin coats coupled to the hydrolysis of ATP: role of an uncoating ATPase.

1984 ◽  
Vol 99 (2) ◽  
pp. 734-741 ◽  
Author(s):  
W A Braell ◽  
D M Schlossman ◽  
S L Schmid ◽  
J E Rothman
Keyword(s):  
Atpase Activity ◽  
Atp Hydrolysis ◽  
Low Ph ◽  
Coated Vesicles ◽  
Magnesium Concentration ◽  
Cross Linking ◽  
Dependent Atpase ◽  
Event Triggering ◽  
Hydrolysis Of

ATP hydrolysis was used to power the enzymatic release of clathrin from coated vesicles. The 70,000-mol-wt protein, purified on the basis of its ATP-dependent ability to disassemble clathrin cages, was found to possess a clathrin-dependent ATPase activity. Hydrolysis was specific for ATP; neither dATP nor other ribonucleotide triphosphates would either substitute for ATP or inhibit the hydrolysis of ATP in the presence of clathrin cages. The ATPase activity is elicited by clathrin in the form of assembled cages, but not by clathrin trimers, the product of cage disassembly. The 70,000-mol-wt polypeptide, but not clathrin, was labeled by ATP in photochemical cross-linking, indicating that the hydrolytic site for ATP resides on the uncoating protein. Conditions of low pH or high magnesium concentration uncouple ATP hydrolysis from clathrin release, as ATP is hydrolyzed although essentially no clathrin is released. This suggests that the recognition event triggering clathrin-dependent ATP hydrolysis occurs in the absence of clathrin release, and presumably precedes such release.

scholarly journals A BIOCHEMICAL AND CYTOCHEMICAL STUDY OF ADENOSINE TRIPHOSPHATASE ACTIVITY IN THE PHLOEM OF NICOTIAN A TABACUM

1974 ◽  
Vol 60 (1) ◽  
pp. 221-235 ◽  
Author(s):  
Jamison Gilder ◽  
James Cronshaw
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Atp Hydrolysis ◽  
Phloem Transport ◽  
Cytochemical Localization ◽  
Gtp Hydrolysis ◽  
Cytochemical Study ◽  
P Protein ◽  
Competitive Inhibitors ◽  
Hydrolysis Of

A biochemical and cytochemical study has been made of the distribution of ATPase in mature and differentiating phloem cells of Nicotiana tabacum and of the substrate specificity and effects of fixation on enzyme activity. Homogenates of unfixed leaf midveins and midveins fixed in formaldehyde-glutaraldehyde were assayed for enzyme activity by determining the amount of Pi, liberated per milligram of protein from various substrates in a 30 min period at pH 7.2. In fresh homogenates, hydrolysis of ATP was not significantly different from that of ITP, CTP, and UTP. Hydrolysis of GTP was slightly higher than that of ATP. ATP hydrolysis by fresh homogenates was 17% more extensive than that of ADP, 76% more extensive than that of 5'-AMP, and was inhibited by fluoride and p-chloromercuribenzoate (PCMB). There was little or no hydrolysis of the competitive inhibitors 2'- and 3'-AMP nor with the alternate substrates p-nitrophenylphosphate (PNP) or ß-glycerophosphate (ß-GP). In homogenates of material fixed in formaldehyde-glutaraldehyde for 1¼ h, ATPase activity was 13% preserved. Hydrolysis of ATP by fixed homogenates was not significantly different from that of ADP, 5'-AMP, ITP, CTP, and GTP. Hydrolysis of UTP was lower. Fluoride and PCMB inhibited fixed ATPase activity. The results of cytochemical localization experiments using a lead phosphate precipitation technique were in agreement with the biochemical results. Similar localization patterns were obtained with the nucleoside triphosphates ATP, CTP, GTP, ITP, and UTP. Activity was also localized with ADP and 5'-AMP but not with the competitive inhibitors 2'- and 3'-AMP, nor with PNP or ß-GP. Little or no reaction product was deposited in other controls incubated without substrate or with substrate plus fluoride, PCMB, or N-ethylmaleimide. ATPase activity was demonstrated chiefly at the plasma membrane of mature and differentiating phloem cells and was associated with the P-protein of mature sieve elements. It is suggested that the phloem transport system derives its energy from the demonstrated nucleoside triphosphatase activity.

scholarly journals Regulation of RUVBL1-RUVBL2 AAA-ATPases by the nonsense-mediated mRNA decay factor DHX34, as evidenced by Cryo-EM

2020 ◽  
Author(s):  
Andrés López-Perrote ◽  
Nele Hug ◽  
Ana González-Corpas ◽  
Carlos F. Rodríguez ◽  
Marina Serna ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Mrna Decay ◽  
Atp Hydrolysis ◽  
Unknown Mechanism ◽  
Macromolecular Complexes ◽  
Wide Range ◽  
Nonsense Mediated Mrna Decay ◽  
Aaa Atpases ◽  
Hydrolysis Of

AbstractNonsense-mediated mRNA decay (NMD) is a surveillance pathway that degrades aberrant mRNAs and also regulates the expression of a wide range of physiological transcripts. RUVBL1 and RUVBL2 AAA-ATPases form an hetero-hexameric ring that is part of several macromolecular complexes such as INO80, SWR1 and R2TP. Interestingly, RUVBL1-RUVBL2 ATPase activity is required for NMD activation by an unknown mechanism. Here, we show that DHX34, an RNA helicase regulating NMD initiation, directly interacts with RUVBL1-RUVBL2 in vitro and in cells. Cryo-EM reveals that DHX34 induces extensive changes in the N-termini of every RUVBL2 subunit in the complex, stabilizing a conformation that does not bind nucleotide and thereby down-regulates ATP hydrolysis of the complex. Using ATPase-deficient mutants, we find that DHX34 acts exclusively on the RUVBL2 subunits. We propose a model, where DHX34 acts to couple RUVBL1-RUVBL2 ATPase activity to the assembly of factors required to initiate the NMD response.

Structure of ATP synthase by SFM and single-particle image analysis

1995 ◽  
Vol 53 ◽  
pp. 722-723
Author(s):  
David Keller ◽  
Seema Singh ◽  
Paola Turina ◽  
Roderick Capaldi ◽  
Carlos Bustamante
Keyword(s):  
Oxidative Phosphorylation ◽  
Particle Image ◽  
Chemical Potential ◽  
Atp Hydrolysis ◽  
High Energy ◽  
Water Soluble ◽  
Unknown Mechanism ◽  
Oxidative Phosphorylation Pathway ◽  
Hydrolysis Of ◽  
Two Sectors

F1Fo ATP synthases are the proteins responsible for the synthesis of ATP in oxidative phosphorylation, and are present in some form in all aerobic organisms, both prokaryotic and eukaryotic. They use the energy stored in a transmembrane proton gradient (which is generated by other members of the oxidative phosphorylation pathway) to synthesize ATP from ADP and Pi or, working in reverse, to pump protons across the membrane using the energy of ATP hydrolysis. The full protein has two sectors, F1 and Fo. F1 is normally bound to Fo (which is membrane integrated), but is water soluble when dissociated. The F1 sector contains the sites which bind ADP and catalyze its conversion to ATP. The Fo sector contains a channel which allows protons to to cross the membrane, dissipating the transmembrane chemical potential. By an unknown mechanism this translocation of protons through Fo is coupled to the hydrolysis or synthesis of ATP in F1, so that the energy released in hydrolysis of ATP can drive the motion of protons against an electrochemical potential, or the energy of translocating protons can be used to form high energy ADP-Pi bonds.

scholarly journals Regulation of RUVBL1-RUVBL2 AAA-ATPases by the nonsense-mediated mRNA decay factor DHX34, as evidenced by Cryo-EM

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Andres López-Perrote ◽  
Nele Hug ◽  
Ana González-Corpas ◽  
Carlos F Rodríguez ◽  
Marina Serna ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Mrna Decay ◽  
Atp Hydrolysis ◽  
Unknown Mechanism ◽  
Macromolecular Complexes ◽  
Wide Range ◽  
Nonsense Mediated Mrna Decay ◽  
Aaa Atpases ◽  
Hydrolysis Of

Nonsense-mediated mRNA decay (NMD) is a surveillance pathway that degrades aberrant mRNAs and also regulates the expression of a wide range of physiological transcripts. RUVBL1 and RUVBL2 AAA-ATPases form an hetero-hexameric ring that is part of several macromolecular complexes such as INO80, SWR1, and R2TP. Interestingly, RUVBL1-RUVBL2 ATPase activity is required for NMD activation by an unknown mechanism. Here, we show that DHX34, an RNA helicase regulating NMD initiation, directly interacts with RUVBL1-RUVBL2 in vitro and in cells. Cryo-EM reveals that DHX34 induces extensive changes in the N-termini of every RUVBL2 subunit in the complex, stabilizing a conformation that does not bind nucleotide and thereby down-regulates ATP hydrolysis of the complex. Using ATPase-deficient mutants, we find that DHX34 acts exclusively on the RUVBL2 subunits. We propose a model, where DHX34 acts to couple RUVBL1-RUVBL2 ATPase activity to the assembly of factors required to initiate the NMD response.

scholarly journals A HISTOCHEMICAL STUDY OF ADENOSINE TRIPHOSPHATASE IN THE TOAD (BUFO SPINULOSUS) GASTRIC MUCOSA

1970 ◽  
Vol 18 (5) ◽  
pp. 340-353 ◽  
Author(s):  
CECILIA KOENIG S. ◽  
JUAN D. VIAL C.
Keyword(s):  
Gastric Mucosa ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Atp Hydrolysis ◽  
Lead Ion ◽  
Outer Side ◽  
Reaction Products ◽  
Fresh Tissue ◽  
Toad Bufo ◽  
Hydrolysis Of

Adenosine triphosphatase (ATPase) activity was studied by histochemical methods in the gastric mucosa of Bufo spinulosus. Two types of activity were established. One is activated by Mg++, and is localized mainly at the intercellular boundaries and the basal zone of the oxyntic-peptic cells; the reaction products are found only on the outer side of the cells. The other is activated by HCO3– and is mainly localized at the microvilli at the apical zone of the oxyntic-peptic cells. The intensity and/or distribution of the reactions are influenced by histamine stimulation. Control experiments demonstrated that: the microsomal fraction of gastric mucosa contained a Mg++-requiring ATPase activity which was enhanced by addition of HCO3–; 25% of the ATPase activity of fresh tissue was maintained after fixation and incubation in presence of lead ion; the medium employed in the histochemical studies did not enhance the lead-catalyzed, nonenzymatic hydrolysis of ATP by more than 20% when compared with spontaneous ATP hydrolysis; and incubation in media with different ATP-Pb ratios did not significantly alter the location of the staining.

scholarly journals LEAD ION AND PHOSPHATASE HISTOCHEMISTRY I. NONENZYMATIC HYDROLYSIS OF NUCLEOSIDE PHOSPHATES BY LEAD ION

1966 ◽  
Vol 14 (10) ◽  
pp. 698-701 ◽  
Author(s):  
ALAN S. ROSENTHAL ◽  
HAROLD L. MOSES ◽  
DAVID L. BEAVER ◽  
SHIRLEY S. SCHUFFMAN
Keyword(s):  
Adenosine Triphosphate ◽  
Atp Hydrolysis ◽  
Linear Increase ◽  
Catalytic Action ◽  
Lead Salt ◽  
Histochemical Localization ◽  
Lead Ion ◽  
High Concentrations ◽  
Rate Limiting ◽  
Hydrolysis Of

A previously undescribed catalytic action of lead ion on the nonenzymatic hydrolysis of nucleoside phosphates has been demonstrated. Lead ion (3.6 mM) hydrolyzed adenosine triphosphate (ATP) at pH 7.2 and 37°C. The presence of magnesium and imidazole was stimulatory. The rate appeared to increase with temperature from 25-60°C. The reaction was inhibited by ethylenediaminetetraacetate. Other nucleoside phosphates were hydrolyzed, some less rapidly than ATP. Adenosine triphosphate in the presence of a rate-limiting amount of lead acted as an inhibitor at high concentrations. With a rate-limiting concentration of ATP (0.72 mM), increasing concentrations of lead ion above 0.36 mM catalyzed a linear increase in ATP hydrolysis. It is suggested that this reaction may be a source of artifact in the lead salt method for the histochemical localization of nucleoside phosphatases.

scholarly journals Vanadate-Induced Trapping of Nucleotides by Purified Maltose Transport Complex Requires ATP Hydrolysis

2000 ◽  
Vol 182 (23) ◽  
pp. 6570-6576 ◽  
Author(s):  
Susan Sharma ◽  
Amy L. Davidson
Keyword(s):  
Atpase Activity ◽  
Atp Hydrolysis ◽  
Binding Protein ◽  
Nucleotide Binding ◽  
Maltose Binding Protein ◽  
High Energy ◽  
Maltose Transport ◽  
Binding Domains ◽  
Mechanism Of Inhibition ◽  
Transport Complex

ABSTRACT The maltose transport system in Escherichia coli is a member of the ATP-binding cassette superfamily of transporters that is defined by the presence of two nucleotide-binding domains or subunits and two transmembrane regions. The bacterial import systems are unique in that they require a periplasmic substrate-binding protein to stimulate the ATPase activity of the transport complex and initiate the transport process. Upon stimulation by maltose-binding protein, the intact MalFGK2 transport complex hydrolyzes ATP with positive cooperativity, suggesting that the two nucleotide-binding MalK subunits interact to couple ATP hydrolysis to transport. The ATPase activity of the intact transport complex is inhibited by vanadate. In this study, we investigated the mechanism of inhibition by vanadate and found that incubation of the transport complex with MgATP and vanadate results in the formation of a stably inhibited species containing tightly bound ADP that persists after free vanadate and nucleotide are removed from the solution. The inhibited species does not form in the absence of MgCl2 or of maltose-binding protein, and ADP or another nonhydrolyzable analogue does not substitute for ATP. Taken together, these data conclusively show that ATP hydrolysis must precede the formation of the vanadate-inhibited species in this system and implicate a role for a high-energy, ADP-bound intermediate in the transport cycle. Transport complexes containing a mutation in a single MalK subunit are still inhibited by vanadate during steady-state hydrolysis; however, a stably inhibited species does not form. ATP hydrolysis is therefore necessary, but not sufficient, for vanadate-induced nucleotide trapping.

Reactions in Activated Peroxide Systems and their Influences on Bleaching Performance

2020 ◽  
Vol 17 ◽  
Author(s):  
Xiaoyan Wang ◽  
Jinmei Du ◽  
Changhai Xu
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Energy Efficiency ◽  
Textile Industry ◽  
High Energy ◽  
Side Reactions ◽  
Competitive Reactions ◽  
High Energy Efficiency ◽  
Hydrolysis Of ◽  
Bleach Activators

Abstract:: Activated peroxide systems are formed by adding so-called bleach activators to aqueous solution of hydrogen peroxide, developed in the seventies of the last century for use in domestic laundry for their high energy efficiency and introduced at the beginning of the 21st century to the textile industry as an approach toward overcoming the extensive energy consumption in bleaching. In activated peroxide systems, bleach activators undergo perhydrolysis to generate more kinetically active peracids that enable bleaching under milder conditions while hydrolysis of bleach activators and decomposition of peracids may occur as side reactions to weaken the bleaching efficiency. This mini-review aims to summarize these competitive reactions in activated peroxide systems and their influence on bleaching performance.

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