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Physical driving force of actomyosin motility based on the hydration effect
Author(s) -
Suzuki Makoto,
Mogami George,
Ohsugi Hideyuki,
Watanabe Takahiro,
Matubayasi Nobuyuki
Publication year - 2017
Publication title -
cytoskeleton
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 86
eISSN - 1949-3592
pISSN - 1949-3584
DOI - 10.1002/cm.21417
Subject(s) - myosin , solvation , actin , biophysics , chemical physics , molecular dynamics , muscle contraction , electric field , biology , chemistry , computational chemistry , solvent , physics , biochemistry , anatomy , quantum mechanics
We propose a driving force hypothesis based on previous thermodynamics, kinetics and structural data as well as additional experiments and calculations presented here on water‐related phenomena in the actomyosin systems. Although Szent‐Györgyi pointed out the importance of water in muscle contraction in 1951, few studies have focused on the water science of muscle because of the difficulty of analyzing hydration properties of the muscle proteins, actin, and myosin. The thermodynamics and energetics of muscle contraction are linked to the water‐mediated regulation of protein–ligand and protein–protein interactions along with structural changes in protein molecules. In this study, we assume the following two points: (1) the periodic electric field distribution along an actin filament (F‐actin) is unidirectionally modified upon binding of myosin subfragment 1 (M or myosin S1) with ADP and inorganic phosphate Pi (M.ADP.Pi complex) and (2) the solvation free energy of myosin S1 depends on the external electric field strength and the solvation free energy of myosin S1 in close proximity to F‐actin can become the potential force to drive myosin S1 along F‐actin. The first assumption is supported by integration of experimental reports. The second assumption is supported by model calculations utilizing molecular dynamics (MD) simulation to determine solvation free energies of a small organic molecule and two small proteins. MD simulations utilize the energy representation method (ER) and the roughly proportional relationship between the solvation free energy and the solvent‐accessible surface area (SASA) of the protein. The estimated driving force acting on myosin S1 is as high as several piconewtons (pN), which is consistent with the experimentally observed force.