Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Photophosphorylation by spinach chloroplasts is inhibited after they have been incubated in the dark with either phenylglyoxal or butanedione. Inhibition by phenylglyoxal is strongest when N-ethylmorpholine is the buffer used during the incubation; that by butanedione requires the presence of borate as buffer. The inhibitions are not reversed by simply washing out the inhibitor, suggesting that a covalent modification of one or more arginine residues is responsible. This is supported by the reversibility of the butanedione inhibition if both the inhibitor and borate buffer are removed. ATPase of the chloroplasts, and of extracted protein, is inhibited, whether activated by trypsin or by heating. This indicates that arginine residues of the coupling factor are the probable major site(s) for attack by these modifiers, leading to the observed inhibitions.
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PMID:Arginine modifiers as energy transfer inhibitors in photophosphorylation. 14 62

Latent ATPase, located on the inner surface of protoplast ghosts of Mycobacterium phlei, was unmasked either by trypsin or an impermeable form of trypsin, ethylene maleic anhydride-trypsin. Density gradient experiments showed that the ghost preparations remained intact following trypsin treatment. Evidence was obtained that 125I-trypsin failed to penetrate the ghost membranes. Thus, attempts were made to determine whether the ATPase molecule in the ghost membranes is accessible from the outer surface. Treatment of protoplast ghosts and trypsin-treated ghosts with 125I by the lactoperoxidase method resulted in the labeling of ATPase only in the trypsin-treated ghost preparations. The antibody to latent ATPase inhibited ATPase activity in trypsin-treated ghosts. The changes in the fluorescence polarization of diphenyl hexatriene indicated that trypsin treatment of the ghost membranes resulted in an increase in membrane fluidity. These studies suggest that the latent ATPase moiety has undergone translocation to the outer surface or it became accessible to trypsin digestion from the outer surface of the membranes as a result of removal of some proteins covering ATPase molecule in the membranes.
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PMID:Trypsin-induced changes in the orientation of latent ATPase in protoplast ghosts from Mycobacterium phlei. 14 35

The 20K dalton fragment of Ca2+ + Mg2+-ATPase obtained from th tryptically digested sarcoplasmic reticulum has been further purified using Bio-Gel P-100. This removed low-molecular-weight UV-absorbing and positive Lowry-reacting contaminants. The ionophoric activity of the 20K fragment in both oxidized cholesterol and phosphatidylcholine:cholesterol membranes is unaltered by this further purification. The 20K selectivity sequence in phosphatidylcholine:cholesterol membrane is Ba2+ greater than Ca2+ greater than Sr2+ greater than Mn2+ Mg2+. Digestion of intact sarcoplasmic reticulum vesicles with trypsin, which results in the dissection of the hydrolytic site (30K) from the ionophoric site (20K), is shown to disrupt energy transduction between ATP hydrolysis and calcium transport. This further implicates the 20K dalton fragment as a calcium transport site. These data and previous evidence are discussed in terms of a proposed model for the ATPase molecular structure and the mechanisms of cation transport in sarcoplasmic reticulum.
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PMID:Active calcium treatment transport via coupling between the enzymatic and the ionophoric sites of Ca2+ + Mg2+-ATPase. 14 15

The coupling factor, F1-ATPase of Escherichia coli (ECF1) contains five different subunits, alpha, beta, gamma, delta, and epsilon. Properties of delta-deficient ECF1 have previously been described. F1-ATPase containing only the alpha, beta, and gamma subunits was prepared from E. coli by passage of delta-deficient ECF1 through an affinity column containing immobilized antibodies to the epsilon subunit. The delta, epsilon-deficient enzyme has normal ATPase activity but cannot bind to ECF1-depleted membrane vesicles. Both the delta and epsilon subunits are required for the binding of delta, epsilon-deficient ECF1 to membranes and the restoration of oxidative phosphorylation. Either delta or epsilon will bind to the deficient enzyme to form a four-subunit complex. Neither four-subunit enzyme binds to depleted membranes. The epsilon subunit, does, however, slightly improve the binding affinity between delta and delta-deficient enzyme suggesting a possible interaction between the two subunits. Neither subunit binds to trypsin-treated ECF1, which contains only the alpha and beta subunits. A role for gamma in the binding of epsilon to F1 is suggested. epsilon does not bind to ECF1-depleted membranes. Therefore, the in vitro reconstitution of depleted membranes requires an initial complex formation between epsilon and the rest of ECF1 prior to membrane attachment. Reconstitution experiments indicate that only one epsilon is required per functional ECF1 molecule.
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PMID:The epsilon subunit of Escherichia coli coupling factor 1 is required for its binding to the cytoplasmic membrane. 14 71

An isolation procedure is worked out and properties are studied of CF1 ATPase from chloroplasts with changed submolecular structure. The enzyme, isolated by chlorophorm treatment, produced Ca-dependent ATPase activity in water solution. As compared with the enzyme isolated by well known Lien and Racker method, the enzyme preparation obtained is slightly activated by heating, is not activated by trypsin and has a lesser ability to recover ATP synthesis in EDTA-treated chloroplasts. Purification on DEAE-Sephadex produced the enzyme preparation free of delta-subunit. Chlorophorm treatment is suggested to change submolecular protein structure, in particular, loosening of the link of delta-subunit with other enzyme subunits. The data obtained suggest that delta-subunit participates in the binding of CF1 ATPase with chloroplast membrane.
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PMID:[Isolation and properties of CF1 ATPase chloroplasts with changed submolecular structure]. 14 26

The membrane-bound, solubilized, and trypsin-treated forms of Mg, Ca-ATPase from E. coli are inhibited by ruthenium red [RR]. The inhibition is noncompetitive and is reduced at higher substrate concentrations. n-Butanol-extracted ATPase is not inhibited by ruthenium red and is not activated by KCl.
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PMID:Inhibition of Mg, Ca-ATPase from E. coli by ruthenium red. 14 51

Incubation of the Ca2+,Mg2+-activated adenosine triphosphatase of Escherichia coli with phospholipid vesicles resulted in binding of the enzyme to the lipid. Binding was observed with vesicles of soybean phospholipid (asolectin), phosphatidyglycerol, phosphatidylserine, phosphatidylcholine, and cardiolpin. Binding was not affected by alterations in pH in the range of pH 6.5 to 8.5, by ionic strength, or by the presence of Mg2+. Loss of the delta subunit from the enzyme had no effect on binding. However, removal of the delta and epsilon subunits by treatment of the enzyme with trypsin prevented binding to phospholipid. This treatment also removed a small portion (less than 2000 daltons) of the alpha subunit. It is concluded that the ATPase of E. coli binds to phospholipid vesicles mainly by nonpolar interactions through the alpha and (or) epilson subunits of the enzyme.
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PMID:Binding of the Ca2+,Mg2+-activated adenosine triphosphatase of Escherichia coli to phospholipid vesicles. 14 87

Dithiobis (succinimidyl propionate) has been used to cross-link sarcoplasmic reticulum microsome proteins. Although the 100,000 dalton calcium stimulated ATPase and the 60,000 dalton calcium-binding protein calsequestrin were readily cross-linked to form homopolymers, no heteropolymer formation between these two proteins were detected. The 90,000 dalton protein A1 which is always observed in our preparations appeared to preferrentially form dimers on cross-linking. When calsequestrin was solubilized using 0.1 mg deoxycholate/mg protein, this protein was not cross-linked even at dithiobis(succinimidyl propionate) concentrations ten times those used to cross-link this protein in the intact membrane. In a similar manner the deoxycholate-solubilized ATPase (0.5 mg deoxycholate/mg protein) was not cross-linked by dithiobis (succinimidyl propionate). These results suggest that the state of aggregation of the sarcoplasmic reticulum proteins may be modified when solubilized in detergents such as deoxycholate. When the 100,000 dalton ATPase polypeptide was cleaved with trypsin to two fragments with molecular weights of approximately 55,000, these could be readily cross-linked. The fragments were capable of forming polymers with either other 55,000 dalton fragments or with the 100,000 dalton ATPase. The 29,000 and 22,000 dalton fragments, produced by further tryptic cleavage of the 55,000 dalton fragments, were not cross-linked at dithiobis (succinimidyl propionate) concentrations which readily cross-linked the 55,000 dalton fragments. Thus tryptic cleavage of the ATPase to fragments smaller than 55,000 dalton altered associations made by the ATPase in the membrane.
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PMID:The effects of deoxycholate and trypsin on the cross-linking of rabbit skeletal muscle sarcoplasmic reticulum proteins. 15 Feb 90

Human red blood cells (RBC) contain a cytoplasmic, nonhemoglobin protein which activates the (Ca2+-Mg2+)ATPase of isolated RBC membranes. Results presented in this paper confirm that activation of (Ca2+-Mg2+)ATPase is associated with binding of the cytoplasmic activator to the membrane. Binding of the cytoplasmic activator is reversible and dependent on ionic strength and Ca2+. Cytoplasmic activator is sensitive to trypsin but is not degraded when intact RBC are exposed to trypsin. Cytoplasmic activator does not modify the (Ca2+-Mg2+)-ATPase of membranes from RBC exposed to activator prior to hemolysis. Thus, the activator is located in the cell and appears to act by binding to the inner membrane surface.
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PMID:Interaction between cytoplasmic (Ca2+--Mg2+) ATPase activator and the erythrocyte membrane. 15 Nov 72

1. The effect of energy transfer inhibitors on energy-dependent exchange of tightly bound adenine nucleotides with washed, broken spinach thylakoids has been studied. Energy transfer inhibitors that inhibit the ATPase activity of soluble chloroplast coupling factor 1 (CF1) (e.g. phloridzin and tentoxin) do not inhibit energy-dependent adenine nucleotide exchange. Energy transfer inhibitors that block proton flux through the hydrophobic protein proton channel (CF0) (e.g. dicyclohexylcarbodiimide and triphenyltin chloride) also block light-dependent adenine nucleotide exchange. 2. Tentoxin, at relatively high concentrations, stimulates an energy-independent exchange of adenosine diphosphate. 3. High concentrations of tentoxin elicit a Ca2+-dependent ATPase activity with soluble CF1, but has no effect on the Ca2+-dependent ATPase activity of membrane-bound CF1. 4. The trypsin-activated, Ca2+-dependent, membrane-bound ATPase is not affected by high concentrations of tentoxin, whereas the dithiothreitol-activated, Mg2+-dependent ATPase is markedly inhibited. 5. The reconstitution of chloroplasts, partially depleted in CF1, with soluble CF1 is correlated with the loss of tentoxin-induced, Ca2+-dependent ATPase activity associated with soluble CF1.
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PMID:Tentoxin-induced energy-independent adenine nucleotide exchange and ATPase activity with chloroplast coupling factor 1. 15 81


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