Members of the myosin superfamily have evolved sequences and structures that are optimized for specific biomechanical roles. Myosin sequences have also been optimized across species to fulfill unique needs. Despite the diversity of myosin sequences, crystallographic studies have shown a preservation of conformations sampled during the cross-bridge cycle. Thus, there exist some dynamic modes that are ‘intrinsic’ to myosins while other dynamic modes are species- or isoform-specific. We previously performed molecular dynamics simulations of the myosin II motor domain (S1) from Dictyostelium discoideum in the pre- (S1 + Mg2+ + ADP + Pi) and post-powerstroke (S1 + Mg2+ + ADP) stages of the cross-bridge cycle. An additional set of simulations was performed with 2-deoxy-ADP (dADP) in the active site instead of the canonical ADP. To advance our model of myosin dynamics in solution, we are investigating newly built systems of myosin II from Argopectans irradians. Molecular dynamics simulations of A. irradians myosin will be analyzed and compared against prior simulations of D. discoideum myosin. This analysis should identify dynamic signatures that are intrinsic to myosins as well as ones that may be species or isoform-specific. Simulations performed in the presence of dADP (in lieu of ADP) will also be analyzed to determine whether previously observed dADP-induced effects on myosin structure and dynamics are similarly induced in scallop myosin. The A. irradians structures have a higher coverage of the motor domain sequence relative to the D. discoideum ones and include a fully resolved converter domain and the essential and regulatory light chain binding regions of the lever arm. Analysis of the dynamics of these critical subdomains in myosin will advance our understanding of how small structural arrangements propagate through myosin heads.