ヘリックス・コイル転移にもとづく筋収縮機構

抄録

The central problem in muscle research today is to understand the molecular mechanism of the force-generating event. There is a large body of well-established evidence that the HMM regions of myosin are the elements responsible for the generation of contractile force. The current models on the muscle contraction, Huxley (1969, 1984), Huxley-Simmons (1971) and helix-coil transition (1971, 1979), are discussed in this review. Within muscle, the chemical event (hydrolysis of ATP) is coupled with a mechanical event (force generation due to structural changes). Two discrete models are equally possible, either the mechanochemical events are directly coupled with S-1 of myosin or indirectly coupled (S-1 hydrolyzes ATP but force is generated with the S-2 region of the myosin rod). Recent biochemical evidence strongly suggests that a substantial amount of melting within the S-2 hinge domain (over 200A in length) occurs upon activation of muscle. These findings favor the "helix-coil" transition model as the most likely mechanism.