Biophysical Journal 71: 576-589 (1996)
© 1996 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Díaz Baños, F G Articles by Svensson, A Search for Related Content PubMed PubMed Citation Articles by Díaz Baños, F G Articles by Svensson, A

Small segmental rearrangements in the myosin head can explain force generation in muscle.

Departamento de Química Física, Universidad de Murcia, Spain.

ABSTRACT

Poisson-Boltzmann calculations of the distribution of electrostatic potentials around an actin filament in physiological-strength solutions show that negative isopotential surfaces protrude into the solvent. Each protrusion follows the actin two-start helix and is located on the sites implicated in the formation of the actomyosin complex. Molecular dynamic calculations on the S1 portion of the myosin molecule indicate that in the presence of ATP the crystallographically invisible loops (comprising residues 624-649 and 564-579) remain on the surface, whereas in the absence of ATP they can move toward the actin-binding sites and experience electrostatic forces that range from 1 to 10 pN. The molecular dynamics calculations also suggest that during the ATP cycle there exist at least three states of electrostatic interactions between the loops and actin. Every time a new interaction is formed, the strain in the myosin head increases and the energy of the complex decreases by 2kT to 5kT. This can explain muscular contraction in terms of a Huxley-Simmons-type mechanism, while requiring only rearrangements of small mobile S1 segments rather than the large shape changes in the myosin molecule postulated by the conventional tilting head model.

This article has been cited by other articles:

				T. Yamada, Y. Takezawa, H. Iwamoto, S. Suzuki, and K. Wakabayashi Rigor-Force Producing Cross-Bridges in Skeletal Muscle Fibers Activated by a Substoichiometric Amount of ATP Biophys. J., September 1, 2003; 85(3): 1741 - 1753. [Abstract] [Full Text] [PDF]