BIO270H1 Lecture Notes - Lecture 8: Duty Cycle, Myocyte, Hydrolysis
Document Summary
Lecture 8 (november 11, 2015): movement and muscle physiology. Majority of movement that involves actin polymers uses myosin. Most studied myosin: myosin i and v, myosin ii involved in transport. Mainly muscle specific hexamer of 2 heavy chains. Myosin heads have atpase and the actin binding site. Myosin neck region is responsible for regulation of atpase. Myosin takes chemical energy and turns it into a mechanical change. Main processes: chemical reaction: myosin binding to actin creation of the cross-bridge, structural change: myosin bends the power stroke this process is a cycle. Without atp, myosin cannot release actin factors affecting movement: unitary displacement distance myosin extends during the cross-bridge cycle dependent on structure of myosin, neck length, and location of the binding site on actin actin is helical. Myosin v (dimer) steps 36 nm every time: duty cycle proportion of time that myosin is actually bound to actin around 0. 5.
