筋を構成するアクトミオシン系の運動機能発現メカニズム解明のための分子動力学解析

抄録

The muscle contraction occurs due to the relative sliding motion between the thick myosin and thin actin filaments. Actomyosin is a molecular machine that transfers chemical energy produced by ATP hydrolysis to kinetic energy. The investigation of muscle contractile mechanism at the atomic/molecular level has been motivated, because X-ray structures of actin and myosin SI monomer have been determined. Therefore, in order to study the structural heterogeneity and atomic fluctuation which can be related to the kinetic function, the molecular structure analysis of actomyosin has been carried out by using the molecular mechanics simulation code"AMBER". 3-D molecular structures of actomyosin adopt three models which consist of three kinds of myosin Sl (without ATP, with ATP, and with ADP) and F-actin to reveal the fundamental micro-mechanism of motility assay. The minimum-energy conformations of actomyosin in three cases are determined by molecular mechanics analysis. The differences of atomic coordinates and potential energy distributions show the existence of the local packing and heterogeneous material characteristics. Next, the fluctuations of those conformations are studied by the molecular dynamics analyses. The fluctuations reveal the dynamic properties at the atomic level and the possibility of meso-scale structural changes and emerging the whole molecular motion.