Adsorption-induced inactivation of heavy meromyosin on polymer surfaces imposes effective drag force on sliding actin filaments in vitro

Actin and myosin are of interest as potential force-generating elements in engineered nanodevices. Such applications require surface coatings which are both biocompatible and amenable to nanolithographic processing, but the manner in which surfaces modulate motor protein function has not been rigorously studied. Here we examine motor protein surface density and bioactivity on a variety of polymer surfaces, and compare the results to in vitro actomyosin motility characteristics. Filament velocities were found to be controlled by the proportion, rather than density, of active heavy meromyosin (HMM), consistent with the imposition of an effective drag force by inactivated HMM due to weak actin-binding interactions. Interpretation of the results with respect to previous models suggests that the inactive HMM fraction has no force-generating ability, and that the effective drag imposed on polystyrene is lower than that on methacrylate polymers and nitrocellulose, consistent with a higher degree of protein denaturation on aromatic surface structures