The theory of sliding filament models for muscle contraction. II. Biochemically-based models of the contraction cycle.
A seven-state sliding filament model is proposed which differs from the model of Eisenberg & Greene. It is based on a simplified version of the in-vitro contraction cycle of Stein et al., and also has some desirable dynamical features of the empirical three-state model of Nishiyama & Murase. Appropriate x-dependences for all reaction rates are derived from the transition-state theory. The seventh-state is assumed to be a high-tension intermediate of A.M.ATP, from which direct but x-dependent dissociation can occur. If the final A.M.ATP state has a sufficiently lower tension than that of A.M.ADP.Pi, then the dominant escape path from the intermediate state is shown to be direct dissociation of the actin-myosin bond. This leads to an approximate five-state model for active and relaxed muscle in which A.M and the final A.M.ATP state are omitted.
Smith
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Physics Department, Monash University, Clayton, Victoria, Australia.
D000199:Actins / Q000502:physiology; D000818:Animals; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000502:physiology*; D009218:Myosins / Q000502:physiology
D000199:Actins; D009218:Myosins