Delayed dissociation of in vitro moving actin filaments from heavy meromyosin induced by low concentrations of Triton X-100.
Biophys Chem
; 67(1-3): 199-210, 1997 Sep 01.
Article
in En
| MEDLINE
| ID: mdl-9397525
ABSTRACT
The in vitro motility of fluorescent actin filaments over heavy meromyosin (HMM) was studied in the presence of the nonionic detergent Triton X-100. Below 0.004% Triton X-100 concentration, motility was not affected. Above 0.007%, motility was not observed because actin filaments were dissociated from HMM. In the Triton X-100 concentration range of 0.004-0.007%, the sliding actin filaments dissociated from HMM with a delay. The dissociation delay time decreased with increasing Triton X-100 concentration, increasing ATP (adenosine-5'-triphosphate) concentration, and increasing temperature. The delayed acto-HMM dissociation was absent when weak-binding kinetic intermediates of the myosin ATPase cycle (M.ATP and M.ADP-Pi) were used. The presence of sliding movement was necessary to evoke the delayed acto-HMM dissociation. The acto-HMM dissociation delay was independent of actin filament length. For a given Triton X-100 concentration, the dissociation delay time was found to be inversely proportional to sliding velocity, indicating that actin filaments travel a more or less constant distance prior to dissociation from HMM. The actin-activated HMM ATPase activity was not inhibited by Triton X-100; rather, it was slightly enhanced. The results imply the presence of a motility-associated conformational change in acto-HMM.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Actins
/
Octoxynol
/
Myosin Heavy Chains
Language:
En
Journal:
Biophys Chem
Year:
1997
Document type:
Article
Affiliation country:
Hungary