Conformational change actomyosin

The basic mechanism for force generation is accepted to be the same in all three vertebrate muscle types the cyclic interaction between actin and myosin (Taylor, 1987). The binding of ATP to actomyosin (AM), hydrolysis of ATP, and eventual release from AM of ADP and Pj results in a large change in free energy that is translated into a force-producing conformation change and translocation of thin and thick filaments relative to one another. 

Terada TP, Sasai M, Yomo T. 2002. Conformational change of the actomyosin complex drives the multiple stepping movement. Proceedings of the National Academy of Sciences of USA 99 9202. 

The mode of inhibition of actomyosin ATPase by calponin differs from that of caldesmon. The effect is mainly on the Vmax with only minor effects on the Km (Nishida et al. 1990, Horiuchi and Chacko 1991). Calponin is shown to affect strongly bound myosin (EL-Mezgueldi and Marston 1996, Borovikov et al. 1996). The inhibition is not dependent on tropomyosin (Winder and Walsh 1990) and the effects of calponin are due to changes in the actin conformation (Noda et al. 1992, Borovikov et al. 1996). 

---