The interaction between actin and myosin is the bases of many cellular force generating processes, most notably muscle contraction. An atomic resolution structure of the actomyosin complex has long eluded researchers, complicated by the propensity of actin to polymerize into a non-crystallizable filament. Obtaining a crystallizable form of the actomyosin complex requires that the actin component of the complex be modified to prevent polymerization; yet, it must still retain the functional characteristics of F-actin. In this thesis I present the development and characterization of three longitudinal actin dimers and a high-throughput assay to screen F-actin structures. This work has been performed as part of an overall research plan to explore and elucidate the protein-protein interactions of the actomyosin complex that lead to the generation of force.