Enzyme of the month May edition-Acetylcholinesterase

Have you ever wondered how your muscles contract? How the muscles allow you to run, walk, write or even digest your food? It is all thanks to the muscle contraction mechanism which involves an important neurotransmitter known as “Acetylcholine.” Let us dive into some brief details about this process. Now you might wonder where does our enzyme of the month-Acetylcholinesterase falls into this sweet muscle contraction story. Do not worry we will be going over our enzyme of the month and its importance. 

            An important aspect of muscle contraction is the generation of the action potential. How is this action potential generated? The answer is the neurotransmitter Acetylcholine. When this neurotransmitter binds to the receptor, the process of muscle contraction begins. If you want to explore the complexity of the muscle contraction, please refer to the image below: 



Image citation link: http://legacy.owensboro.kctcs.edu/gcaplan/anat/notes/api%20notes%20j%20%20muscle%20contraction.htm

As seen in the picture above, for contraction to take place, the step of the ACh binding to the receptor is super important. However, I am sure you do not want to keep running forever and you do not want to digest food when you have not eaten in a while. So what causes the muscle contraction to stop? This is where our enzyme of the month- Acetylcholinesterase comes into the picture. As a typical enzyme, it catalyzes the breakdown of the neurotransmitter into acetic acid and choline. And as structure defines the function, the neurotransmitter cannot bind to the receptor anymore and the contraction stops. This allows you to stop running when you are tired. 

            Have you wondered what might happen if this awesome enzyme stops working? The inhibitors of this enzyme are referred to as organophosphates and are commonly used in agricultural pesticides2.In fact, many researchers have raised their concerns about over-exposure to the organophosphates to humans through the food consumed. A common condition caused by the organophosphates is muscle fasciculations or involuntary muscular contractions2. Another condition that might result from organophosphates is bradycardia (a condition associated with slower heart rate). Hence through the pathologies described above, we can really evaluate the importance of our enzyme of the month. 

            I hope that this month’s edition of the Enzyme of the Month series has helped you to really understand the importance of the enzymes. As always please remember to respect the amazing complexities of biochemistry. 

 

References:

1.      Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. Acetylcholine. Available from: https://www.ncbi.nlm.nih.gov/books/NBK11143/

2.      Trang A, Khandhar PB. Physiology, Acetylcholinesterase. [Updated 2020 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539735/

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