Document Detail


ATP-induced dissociation of rabbit skeletal actomyosin subfragment 1. Characterization of an isomerization of the ternary acto-S1-ATP complex.
MedLine Citation:
PMID:  3828289     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S) induced dissociation of actomyosin subfragment 1 (S1) has been investigated by monitoring the light scattering changes that occur on dissociation. We have shown that ATP gamma S dissociates acto-S1 by a mechanism similar to that of ATP but at a rate 10 times slower. The maximum rate of dissociation is limited by an isomerization of the ternary actin-S1-nucleotide complex, which has a rate of 500 s-1 for ATP gamma S and an estimated rate of 5000 s-1 for ATP (20 degrees C, 0.1 M KCl, pH 7.0). The activation energy for the isomerization is the same for ATP and ATP gamma S, and both show a break in the Arrhenius plot at 5 degrees C. The reaction between acto-S1 and ATP was also followed by the fluorescence of a pyrene group covalently attached to Cys-374. We show that the fluorescence of the pyrene group reports the isomerization step and not actin dissociation. The characterization of this isomerization is discussed in relation to force-generating models of the actomyosin cross-bridge cycle.
Authors:
M A Geeves; T E Jeffries; N C Millar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemistry     Volume:  25     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  1986 Dec 
Date Detail:
Created Date:  1987-05-20     Completed Date:  1987-05-20     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  8454-8     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphate / metabolism*
Animals
Kinetics
Light
Muscles / metabolism*
Myosin Subfragments
Myosins / metabolism*
Peptide Fragments / metabolism*
Protein Binding
Rabbits
Scattering, Radiation
Spectrometry, Fluorescence
Thermodynamics
Chemical
Reg. No./Substance:
0/Myosin Subfragments; 0/Peptide Fragments; 56-65-5/Adenosine Triphosphate; EC 3.6.4.1/Myosins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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