Key result
The association constant for heavy meromyosin binding to F-actin was 1 X 10(7) M-1, compared to 3 X 10(6) M-1 for subfragment 1, suggesting only one head binds strongly at a time.
Population
In vitro biochemical model (myosin subfragments and F-actin)
Design
Preclinical
Authors
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Informs actomyosin models; leaves open relevance to cardiac sarcomere function in vivo.
The small difference in binding energy between heavy meromyosin and subfragment 1 suggests that either only one head binds strongly to actin at a time or free energy is lost during the attachment of two heads.
Margossian et al. (1978) studied this question. Heavy meromyosin (HMM) and subfragment 1 (S1) was evaluated on Association constant (Ka) for binding to F-actin. The association constant for heavy meromyosin binding to F-actin was 1 X 10(7) M-1, compared to 3 X 10(6) M-1 for subfragment 1, suggesting only one head binds strongly at a time.
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