Fig. 6. The dynamics of ATP binding and hydrolysis by the myosin constructs were analyzed in terms of the models shown in Schemes 1-3, where M refers to myosin head fragment, A to actin, and T, D and P_i to ATP, ADP and phosphate, respectively. In these schemes, a notation is used that distinguishes between the constants in the presence and absence of actin by using bold (K₊₁, K₁) versus italic type (k₊₁, K₁); subscript A and D refer to actin (K_A) and ADP (K_D), respectively.