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第10回ＣＯＥ(自己組織系物理)セミナー (通算15回)
| “Stochastic models of molecular motors” |
| 講 師 |
Prof. P. Gaspard(ベルギーブラッセル自由大学教授)
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| 日 時 |
2005年3月23日（水） 15:00-16:30 |
| 場 所 |
早稲田大学理工学部55号館N棟2階応物・物理会議室 |
| 講演の概要 |
Molecular motors are working under nonequilibrium conditions
and can be modeled at the microscopic level in terms of
stochastic processes which take into account
the molecular fluctuations. They are responsible
not only for the Langevin-type fluctuating
force but also for the randomness of the chemical reactions,
leading to chemomechanical models based
on coupled Fokker-Planck equations.
A stochastic model of the F_1-ATPase rotary motor is presented
which has six chemical states in addition to the continuous rotation
angle.
This model remarkably reproduces the experimentally observations,
in particular, the Michaelis-Menten dependence of the rotation rate
on the ATP concentration. The crossover observed in the dependence
of the rotation rate on the friction is interpreted as a transition
between a reaction-limited regime and a friction-limited regime.
Furthermore, the same type of stochastic models can be
applied to the actin-myosin cross-bridge cycle.
Here, the presented model has three chemical states in addition to the
continuous relative position of myosin with respect ot actin.
Collective effects emerge upon the coupling of
many such linear motors, resulting into a transition
in the dependence of the velocity on the external force.
This dependence is used to explain the spontaneous
oscillations in muscle contraction as well as the propagation
of nonlinear waves along muscles.
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| 紹介教員 |
田崎秀一 |
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