DEPENDENCE OF THE MYOFIBRILLAR CONTRACTIO N VELOCITY ON THE MGATP CONCENTRATION - A THEORETICAL-STUDY

We propose simple model for the mechano-biochemical cycle of the myosi n cross-bridges, taking into account the contribution of ''slow bindin g'' bridges in the negative strength. Mathematical analysis of this mo del allowes us to obtain an analytical expression for the dependence o f the contraction velocity on the MgATP concentration. Parameters of t his equation are rate constants of dissociation of ''slow binding'' br idges from thin filament, liberation of inorganic phosphate and bindin g of MgATP. The model leads to the bell-shaped dependence of myofibril lar contraction velocity on the substrate concentration similar to the experimental one. The values of above mentioned constants for the iso lated myofibrils are estimated to be close to values obtained in unstr uctured contractile models.