Lymn-Taylor model

The fourth actin-bound, top-of-powerstroke state is ephemeral. In the original Lymn—Taylor model it is not clear if this fourth state is strongly or weakly bound to actin, but P release, ADP release, and force generation all occur during the transition 4 to 1. Thus, in the following discussion, we attempt to break this transition down into a series of elementary events and to explore if it is possible to order the biochemical and mechanical events and to correlate them with structural changes. 

Myosin as an ATPase Activation of Myosin ATPase by Actin Lymn and Taylor Model 1971 Eisenberg and Hill Model 1985... 

All these experiments were carried out with actin and myosin in solution, either using moderate ionic strength and low actin concentrations (Lymn and Taylor, 1971) or using low ionic strength and high actin concentrations (Stem et al., 1979). However, in muscle both the actin concentration and the ionic strength are high. To confirm these models, these same experiments need to be carried out in muscle fibers. 

Much is known about the steps in the biochemical reaction of ATP breakdown by myosin and how these relate to the production of force by the crossbridge. However, since it is no longer attached to the myosin thick filament, myosin SI cannot be an adequate model for a strained crossbridge. Thus data from muscle fibers (e.g., the dependence of phosphate affinity on strain) must also be considered. In this review we attempt to summarize the currently known structural data on myosin and produce a synthesis of this with the biochemical data. We start with an analysis of the polymorphism of the myosin crossbridge and relate this to the crossbridge cycle proposed by Lymn and Taylor (1971). 

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