Estimation of cross-bridge stiffness from maximum thermodynamic efficiency.

摘要: In muscle, work is performed by myosin cross-bridges during interactions with actin filaments. The amount of each interaction can be related to the mechanical properties cross-bridge; integral force produced respect distance that cross-bridge moves filament, and determined stiffness attached cross-bridge. this paper, in frog sartorius muscle was estimated from thermodynamic efficiency (work/free energy change) using a two-state model, assuming constant over working range tight-coupling between cross- bridge cycles ATP use. This model accurately predicts (work/enthalpy output). A critical review literature indicates realistic value for maximum 0.45 under conditions commonly used experiments on isolated muscle. Cross-bridge power stroke amplitudes. For amplitudes (10–15nm), 1 2.2pNnm−1. These values are similar those quick-release experiments, taking into account compliance arising structures other than cross-bridges, but substantially higher protein studies. effects estimates relaxing requirement incorporating more force-producing states also considered.