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:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synaptic vesicles prepared from bovine corpus striatum exhibit an ATPase activity that is insensitive to ouabain and specific inhibitors of mitochondrial ATPase, but that is stimulated by proton ionophores and inhibited by sulfhydryl reagents. Low concentrations of orthovanadate, DCCD and tributyl tin are also ineffective as inhibitors of the vesicle-associated activity. The properties of the synaptic vesicle enzyme suggest that this ATPase may be similar to that of clathrin-coated vesicles, and to one of the activities described in preparations of adrenal chromaffin granule membranes.
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PMID:Properties of the bovine striatal synaptic vesicles ATPase. 623 19

Eadie-Hofstee plots (v/[S] vs. v) of the kinetics of ATP hydrolysis by purified bovine heart mitochondrial F1-ATPase (MF1) over a substrate (MgATP) concentration range of 1-5000 microM were curvilinear, indicating negative cooperativity with respect to [MgATP] as originally shown by Ebel & Lardy (1975) [Ebel, R. E., & Lardy, H. A. (1975) J. Biol. Chem. 250, 191-196]. The data were computer analyzed for the best fit of the least number of straight lines, each representing a different apparent Km and Vmax. The best fits for MF1 and TF1 from the thermophilic bacterium PS3 were three lines in each case. The upper limits of the apparent Km values for MF1 were of the order of 10(-6), 10(-4), and 10(-3) M, and the corresponding apparent Vmax values (per minute per milligram of protein) were in the range of micromoles or less for the lowest Km line and decamicromoles for the other two. The results for TF1 were very similar. The presence of an activating anion (10 mM KHCO3) in the MF1 assay medium increased the overall Vmax by about 50% and eliminated the high Km but had essentially no effect on the intermediate and low Km's, indicating retention of negative cooperativity in the corresponding substrate concentration range. Kinetic data for MgITP as substrate also yielded two Km values (in the absence of KHCO3) differing by about 10(4)-fold. The relationship between [14C]dicyclohexylcarbodiimide [( 14C]-DCCD) binding to MF1 and activity inhibition was linear up to approximately 1 mol of DCCD bound/mol of MF1. At this point, the degree of inhibition was about 95%.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Kinetics of ATP hydrolysis by F1-ATPase and the effects of anion activation, removal of tightly bound nucleotides, and partial inhibition of the ATPase by covalent modification. 623 25

The binding of "oligomycin sensitivity conferring protein" (OSCP) to soluble beef-heart mitochondrial ATPase (F1) has been investigated. OSCP forms a stable complex with F1, and the F1 X OSCP complex is capable of restoring oligomycin- and DCCD-sensitive ATPase activity to F1- and OSCP-depleted submitochondrial particles. The F1 X OSCP complex retains 50% of its ATPase activity upon cold exposure while free F1 is inactivated by 90% or more. Both free F1 and the F1 X OSCP complex release upon cold exposure a part--probably 1 out of 3--of their beta subunits; whether alpha subunits are also lost is uncertain. The cold-treated F1 X OSCP complex is still capable of restoring oligomycin- and DCCD-sensitive ATPase activity to F1- and OSCP-depleted particles. OSCP also protects F1 against modification of its alpha subunit by mild trypsin treatment. This finding together with the earlier demonstration that trypsin-modified F1 cannot bind OSCP indicates that OSCP binds to the alpha subunit of F1 and that F1 contains three binding sites for OSCP. The results are discussed in relation to the possible role of OSCP in the interaction of F1 with the membrane sector of the mitochondrial ATPase system.
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PMID:The oligomycin sensitivity conferring protein (OSCP) of beef heart mitochondria: studies of its binding to F1 and its function. 624 46

The amino acid sequence of the proteolipid subunit of the ATP synthase was analyzed in six mutant strains from Escherichia coli K12, selected for their increased resistance towards the inhibitor N,N'-dicyclohexylcarbodiimide. All six inhibitor-resistant mutants were found to be altered at the same position of the proteolipid, namely at the isoleucine at residue 28. Two substitutions could be identified. In type I this residue was substituted by a valine resulting in a moderate decrease in sensitivity to dicyclohexylcarbodiimide. Type II contained a threonine residue at this position. Here a strong resistance was observed. These two amino acid substitutions did not influence functional properties of the ATPase complex. ATPase as well as ATP-dependent proton-translocating activities of mutant membranes were indistinguishable from the wild type. At elevated concentrations, dicyclohexylcarbodiimide still bound specifically to the aspartic acid at residue 61 of the mutant proteolipid as in the wild type, and thereby inhibited the activity of the ATPase complex. It is suggested that the residue 28 substituted in the resistant mutants interacts with dicyclohexylcarbodiimide during the reactions leading to the covalent attachment of the inhibitor to the aspartic acid at residue 61. This could indicate that these two residues are in close vicinity and would thus provide a first hint on the functional conformation of the proteolipid. Its polypeptide chain would have to fold back to bring together these two residues separated by a segment of 32 residues.
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PMID:Identification of amino-acid substitutions in the proteolipid subunit of the ATP synthase from dicyclohexylcarbodiimide-resistant mutants of Escherichia coli. 625 67

The coupling between H+ transport (JH) and anaerobic glycolysis was examined in vitro in an anaerobic preparation of turtle urinary bladder. JH was measured as the short-circuit current after Na+ transport was abolished with ouabain and by pH stat titration. The media were gassed with N2 and 1% CO2 (PO2 less than 0.5 mm Hg) and contained 10 mM glucose. Under these conditions, JH was not inhibited by 3 mM serosal (S) cyanide or by 0.1 mM mucosal (M) dinitrophenol. Control anaerobic lactate production (Jlac) of 47 bladders was plotted as a function of simultaneously measured JH. The slope of Jlac on JH was 0.58 0.12 with an intercept for Jlac at JH = 0 of 0.55 micromol/hr. Values for delta Jlac/delta JH were determined in groups of individual bladders when JH was inhibited by an opposing pH gradient (0.55 0.16), by acetazolamide (0.58 0.19) and by dicyclohexylcarbodiimide, DCCD (0.58 0.14). The constancy of delto Jlac/ delta JH indicates a high degree of coupling between JH and Jlac. Since the anaerobic metabolism of glucose produces one ATP for each lactate formed, the delta Jlac/ delta JH values can be used to estimate the stoichiometry of H+ translocation. The movement of slightly less than 2H+ ions is coupled to the hydrolysis of one ATP. During anaerobiosis (absence of mitochondrial ATPase function) the acidification pump was not inhibited by M addition of oligomycin but was inhibited by M addition of DCCD and Dio-9, inhibitors of H+ flow in the proteolipid portion of H+-translocating ATPases. DCCD inhibited anaerobic JH without change in delta Jlac/delta JH or basal Jlac and, therefore, acted primarily on the H+ pump. S addition of vanadate also inhibited JH, but the inhibition was associated with an increase in Jlac. The site of this apparent uncoupling remains to be defined. The acidification pump of the luminal cell membrane of the turtle bladder has H+-ATPase characteristics that differ from mitochondrial ATPase in that H+ transport is oligomycin-resistant and vanadate-sensitive. As judged from the flows of H+ and lactate, the H+/ATP stoichiometry of the pump is about 2.
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PMID:Coupling between H+ transport and anaerobic glycolysis in turtle urinary bladder: effect of inhibitors of H+ ATPase. 626 81

The nucleotide sequence has been determined of a 2,500 base pair segment of the E. coli chromosome located between 3.75 and 6.25 kb counterclockwise of the origin of replication at 83.5 min. The sequence contains the atp genes coding for subunits a-, b-, c-, delta- and part of the alpha-subunit of the membrane bound ATP synthase. The precise start positions of the atpE (c), atpF (b), atpH (delta) and atpA (alpha) genes have been defined by comparison of the potential coding sequences with the known amino acid sequence of the c-subunit and the determined N-terminal amino acid sequences of the respective subunits. The genes are expressed in the counterclockwise direction. Their order (counterclockwise) is: atpB (a), atpE (c), atpF (b), atpH (delta) and atpA(alpha). The coding sequences for subunits b and delta yield polypeptides of 156 and 177 amino acids, respectively, in accordance with the established sizes of these subunits; the one for the c-subunit, the DCCD binding protein, fits perfectly with its known sequence of 79 amino acids. The a-subunit is comprised within a coding sequence yielding a polypeptide of 271 amino acids. It is suggested, however, that the a-subunit (atpB) contains only 201 amino acids, in accordance with its known size, starting from a translation initiation site within the larger coding sequence. The stoichiometry of the F0 sector subunits is discussed and a model is proposed for the functioning of the highly charged b-subunit of the F0 sector as the actual proton conductor.
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PMID:The nucleotide sequence of the atp genes coding for the F0 subunits a, b, c and the F1 subunit delta of the membrane bound ATP synthase of Escherichia coli. 627 47

The intrinsic membrane sector (Fo) of the H+-ATPase complex of Escherichia coli has been purified, incorporated into liposomes, and its proton-translocating activity reconstituted. The Fo sector was prepared by treating a purified, particulate, F1FO-ATPase preparation with EDTA to solubilize the F1-ATPase. The resulting particulate Fo fraction was incorporated into liposomes of E. coli phospholipids by sonication. Proton efflux from these liposomes was measured with a pH electrode after imposition of a membrane potential. The kinetics of proton efflux fits that predicted by the Goldman-flux equation. The rate of proton efflux was increased maximally more than 100-fold on incorporation of the Fo sector into the liposomes. The rate of H+ efflux varied directly with the amount of Fo material added during reconstitution. Dicyclohexylcarbodiimide blocked Fo-mediated H+ efflux. Inhibition was shown to be due to reaction of dicyclohexylcarbodiimide with a specific proteolipid subunit of Fo. The preparation of Fo used in these studies contained the three proteins that had previously been identified as likely subunits of Fo (Foster, D. L., and Fillingame, R. H. (1979) J. Biol. Chem. 254, 8230-8236). It remains to be determined whether all three components are required for reconstitution of proton translocation activity.
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PMID:Energy-transducing H+-ATPase of Escherichia coli. Reconstitution of proton translocation activity of the intrinsic membrane sector. 644 5

1. The content of the membrane sector of the ATPase complex (Fo) in brown adipose tissue mitochondria was determined by means of specific [14C]-DCCD binding. 2. The specific DCCD binding to the F0 protein was distinguished from the nonspecific binding to the other membrane proteins and phospholipids by: (a) Scatchard plot analysis of the equilibrium binding data, (b) SDS-polyacrylamide gel electrophoresis of the 14C-labelled membrane proteins, (c) partial purification of the chloroform-methanol extractable DCCD-binding protein. It was found that the specific DCCD binding was present in three polypeptides of a relative molecular weight of 9000, 16 000 and 32 000. In brown adipose tissue mitochondria the specific binding was 10-times lower than in heart or liver mitochondria. The binding to the other membrane proteins and to phospholipids was quite similar in all mitochondrial preparations studied. 3. The decreased quantity of the specific binding sites in brown adipose tissue mitochondria demonstrated that the reduction of F0 parallels the reduction of the F1-ATPase and revealed that in these mitochondrial membranes the ratio between the respiratory chain enzymes and the ATPase complex is 10- to 20- times higher than in heart or liver mitochondria.
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PMID:Evaluation of the specific dicyclohexylcarbodiimide binding sites in brown adipose tissue mitochondria. 645 Dec 41

A proton pump in diverse biological systems consists of two structural units with separate but integrated functions, the F0-F1-ATPase. We tested by chemical perturbation the possibility that such a proton pump might be involved in urinary acidification conducted by urinary epithelia (UF0-UF1-ATPase). Tyrosine-reactive chemicals and N,N'-dicyclohexylcarbodiimide, known to block the proton channel unit (F0), also inhibited urinary acidification, as measured by the reverse short-circuit current (RSCC) in urinary bladders from toads and turtles. Since these chemicals were equally effective under aerobic and anaerobic conditions, the inhibition appears to occur directly on UF0 rather than on mitochondria. In contrast, an inhibitor of F0-F1-ATPase, oligomycin, only inhibited aerobic RSCC and was ineffective on anaerobic RSCC. Thus, oligomycin appears to inhibit mitochondrial F0-F1 rather than any UF0+UF1. Another inhibitor of the F1-ATPase unit, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, was without effect on RSCC at a concentration (0.3 mM) that produced over 50% inhibition of short-circuit current. These results support the concept that acidifying urinary epithelia contain a plasma membrane proton channel, UF0, but that UF1, if it exists, is unique in that it is resistant to known inhibitors.
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PMID:Effects of inhibitors of F0-F1 proton-translocating ATPase on urinary acidification. 645 34

The mitochondrial adenosine triphosphatase of the kinetoplastid protozoon, Crithidia fasciculata, is inhibited by oligomycin, venturicidin, triethyltin sulphate, N,N'-dicyclohexylcarbodiimide, leucinostatin, Dio-9 and quercetin, but not spegazzinine or by compounds which interact with the beta-subunit of mitochondrial F1-ATPase (efrapeptin, aurovertin, citreoviridin or 4-chloro-7-nitrobenzofurazan). These results suggest that the F1 portion of the crithidial enzyme has an unusual type of beta-subunit. Further evidence for the atypical nature of this enzyme is provided by the observation that F1-inhibitor proteins from Acanthamoeba castellanii or bovine heart mitochondria do not inhibit the C. fasciculata enzyme activity.
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PMID:Effects of inhibitors on mitochondrial adenosine triphosphatase of Crithidia fasciculata: an unusual pattern of specificities. 645 44


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