KP251 Lecture Notes - Lecture 4: Rigor Mortis, Myosin Head, Atp Hydrolysis
10 Jul 2019
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Document Summary
Muscle proteins: contractile proteins, regulatory proteins, structural proteins. Projections of each myosin molecule protrudes outwards (myosin head) responsible for conversion of atp. Actin molecule provides a site where a myosin head can attach. Strands of tropomyosin that cover the myosin binding sites. Calcium ion binding to troponin moves tropomyosin away from myosin-binding sites. At rest tropomyosin wraps and prevents binding of myosin and actin. In muscular dystrophy rips muscle because there is an absence of dystrophin and when patients are older they loose muscle function. Tropomyosin blocks the troponin sites at rest. The onset of contrition begins with the releasing of calcium ions in the muscle cell. Causes troponin to move away from myosin binding sites on actin. The contractile cycle consists of 4 steps: atp hydrolysis. Hydrolysis of atp reorients and reenergizes the myosin head: formation of cross-bridges. Myosin head attaches to the myosin binding site on the actin: power stroke.
