Actomyosin motor mechanism: Affinity gradient surface force model

Actomyosin is a natural nanomachine which generates a force up to 5pN per skeletal myosin motor domain and moves at a speed of 10 μm s^-1. The working stroke per skeletal myosin motor domain per ATP hydrolysis was evaluated as at least 60 nm by Yanagida et al. (1985 Nature 316:366-369) which lead to the loose coupling model of Oosawa and Hayashi (1986 Advances in Biophysics 22:151-183). A dynamic change of the surface hydrophobicity of the myosin motor domain during the ATP hydrolysis reaction was demonstrated by Suzuki et al. (1997 Biophysical Journal 72:18-23). This paper describes a linear motor model for actomyosin based on an affinity gradient surface force and affinity transition of the protein surface. This model explains the magnitude of the driving force and the force-velocity relation of Edman (1988 Journal of Physiology 404:301-321) and has the potential to explain long-powerstroke movement, which were hardly understood by well-known swinging-crossbridge models.