[Bending fluctuations of the alpha-helix and the dynamics of enzyme-substrate interactions].

A stochastic model is developed for the dynamic behavior of proteins containing relatively rigid structural components. The paper considers the fluctuations of a gap between the rigid components and the dynamics of substrate--gap interactions associated with the formation of the enzyme-substrate complex. Electron-conformation interactions in the physical situation being considered are described by a model involving multiple diffusion movements within the configurational space having an absorption area. It has been shown that the limiting stage of catalysis (tau approximately 10(-2)-10(-4) s) is a specific structural configuration of the active center groups and substrate, formed during conformational motions, through which effective multi-center chemical interactions are made possible.