Linked Life Data

6232948

Source:http://linkedlifedata.com/resource/pubmed/id/6232948

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1984-6-22
pubmed:abstractText
We have previously shown that myosin does not have to detach from actin during each cycle of ATP hydrolysis. In the present study, using the A-1 isoenzyme of myosin subfragment 1, we have investigated the nature of the rate-limiting steps in the ATPase cycle. Our results show that, at 15 degrees C, at very low ionic strength, KATPase determined from the double-reciprocal plot of ATPase activity vs. actin concentration is more than 6-fold stronger than KBINDING determined by directly measuring the binding of A-1 myosin subfragment 1 to actin during steady-state ATP hydrolysis. Computer modeling shows that this large difference between KATPase and KBINDING is not compatible with Pi release being the rate-limiting step in the ATPase cycle. If Pi release is not rate limiting, it is possible that the ATP hydrolysis step, itself, is rate limiting. However, this predicts that, at high actin concentration, the value of the initial Pi burst should be close to zero. Therefore, we measured the magnitude of the initial Pi burst in the presence of actin, using both direct measurement and measurement of relative fluorescence magnitude. Our results suggest that the magnitude of the initial Pi burst in the presence of actin is considerably higher than would be expected if the ATP hydrolysis step were the rate-limiting step in the ATPase cycle.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1555-63
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
The rate-limiting step in the actomyosin adenosinetriphosphatase cycle.
pubmed:publicationType
Journal Article