11 by: Andrea Deis

Student – Andrea Deis
Enzyme – Myosin; EC 3 – Hydrolases

Myosin is an ATPase enzyme found in the muscles of eukaryotes. The main function of myosin is to convert chemical energy from ATP into mechanical energy through a hydrolysis reaction. Muscle contraction is able to happen because of myosin. In skeletal, cardiac and smooth muscles, myosin binds to actin and through the enzymatic reaction with ATP, pulls actin to contract muscles. This is critical in the muscles that are thought about daily, like arms and legs while walking, but also for the muscles around vital organs and bones. For example, myosin is present in the muscles of the lungs that line the airways. Controlled by the automatic nervous system, myosin facilitates the contraction and relaxation of the airways to regulate airflow into the lungs.

One really cool fact about myosin is that when you have a sudden muscle twitch or spasm, it is because myosin is cycling through contraction and relaxation, causing your muscle to twitch!

References:
Cooper, Geoffrey M. “Actin, Myosin, and Cell Movement.” Nih.gov, Sinauer Associates, 2009, www.ncbi.nlm.nih.gov/books/NBK9961/.
Gunst, Susan J. “Airway Smooth Muscle and Asthma.” Muscle, 2012, pp. 1359–1369, www.sciencedirect.com/sdfe/pdf/download/eid/3-s2.0-B9780123815101001046/first-page-pdf, https://doi.org/10.1016/b978-0-12-381510-1.00104-6.
Krans, Jacob L. “Sliding Filament Theory, Sarcomere, Muscle Contraction, Myosin | Learn Science at Scitable.” Nature.com, 2010, www.nature.com/scitable/topicpage/the-sliding-filament-theory-of-muscle-contraction-14567666/.
Lumen Learning. “ATP and Muscle Contraction | Biology for Majors II.” Lumenlearning.com, 2020, courses.lumenlearning.com/wm-biology2/chapter/atp-and-muscle-contraction/.
“Muscle Twitch and Control | Biology for Majors II.” Lumenlearning.com, 2019, courses.lumenlearning.com/wm-biology2/chapter/muscle-twitch-and-control/.