Linked Life Data

9685406

Source:http://linkedlifedata.com/resource/pubmed/id/9685406

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
32
pubmed:dateCreated
1998-9-10
pubmed:abstractText
The ATP hydrolysis of the V1-ATPase of Thermus thermophilus have been investigated with an ATP-regenerating system at 25 degreesC. The ratio of ATPase activity to ATP concentration ranged from 40 to 4000 microM; from this, an apparent Km of 240 +/- 24 microM and a Vmax of 5.2 +/- 0.5 units/mg were deduced. An apparent negative cooperativity, which is frequently observed in case of F1-ATPases, was not observed for the V1-ATPase. Interestingly, the rate of hydrolysis decayed rapidly during ATP hydrolysis, and the ATP hydrolysis finally stopped. Furthermore, the inactivation of the V1-ATPase was attained by a prior incubation with ADP-Mg. The inactivated V1-ATPase contained 1.5 mol of ADP/mol of enzyme. Difference absorption spectra generated from addition of ATP-Mg to the isolated subunits revealed that the A subunit can bind ATP-Mg, whereas the B subunit cannot. The inability to bind ATP-Mg is consistent with the absence of Walker motifs in the B subunit. These results indicate that the inactivation of the V1-ATPase during ATP hydrolysis is caused by entrapping inhibitory ADP-Mg in a catalytic site. Light-driven ATP synthesis by bacteriorhodopsin-VoV1-ATPase proteoliposomes was observed, and the rate of ATP synthesis was approximately constant. ATP synthesis occurred in the presence of an ADP-Mg of which concentration was high enough to induce complete inactivation of ATP hydrolysis of VoV1-ATPase. This result indicates that the ADP-Mg-inhibited form is not produced in ATP synthesis reaction.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
20504-10
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
V-ATPase of Thermus thermophilus is inactivated during ATP hydrolysis but can synthesize ATP.
pubmed:affiliation
Department of Biochemistry, Faculty of Pharmaceutical Science, Kanazawa University, Takara-machi 13-1, Kanazawa, Ishikawa 920, Japan. yokoken@kenroku.kanazawa-u.ac.jp
pubmed:publicationType
Journal Article